The Weather Blog

Retired Hurricane Names from 2008

The 2008 hurricane season in the Atlantic was fairly average (compared to the recent, 1995-present, levels of activity) in terms of the numbers of named storms and hurricanes. There were the highlights, such as all the major hurricanes to strike Cuba, and the impressive late season Hurricane Paloma. With the announcement of three retired storm names, the book can now finally be closed on the 2008 Atlantic hurricane season.

Hurricane Gustav was the strongest storm of the season in terms of its winds, topping out at 150 mph as a high end Category 4 hurricane prior to making landfall in western Cuba. Gustav was directly responsible for at least 112 fatalities, the majority of which occurred in Haiti. Of these deaths, 11 were in the states of Louisiana and Florida. In addition, another 41 persons in Louisiana perished from the indirect effects of Gustav. Property damage was most severe in Cuba when Gustav made landfall at the height of its power, but was also significant in Hispaniola, as well as in Louisiana near its final landfall. The estimated damage total in the U.S. is $4.3 billion. The name Gustav has now been retired, and will be replaced by Gonzalo when the 2008 list comes around again in 2014.

Hurricane Ike was the largest hurricane of the 2008 season in the Atlantic and the costliest in terms of damage, leaving a trail of destruction through the Caribbean, the Gulf Coast, and continuing on to cause damage in the Ohio Valley and even Canada after losing its tropical characteristics. There were 103 direct fatalities from Ike during its life as a hurricane, 20 of which occurred in the U.S., and there were an additional 28 deaths occurring inland over the Ohio Valley after Ike lost tropical characteristics but still produced widespread wind damage. There remain 34 people unaccounted for in Texas as a result of Ike.

Hurricane Ike's property damage is astounding. Over 95% of the houses on Grand Turk Island, along with at least 70% of the houses on Great Inagua Island, were damaged. Ike was the fourth consecutive tropical system to affect Hispaniola (after Fay, Gustav, and Hanna), adding to the misery in Haiti. Cuba suffered agricultural damage as well as damage to infrastructure (several bridges and highways), and many buildings (over 300,000 homes damaged), totaling approximately $3-4 billion. Ike's damage to the U.S. is estimated at $19.3 billion, with an additional $4.7 billion in damages not related to flooding taking place over the Ohio Valley from the extratropical remnants of Ike. Ike has now been retired, and its name will be replaced by Isaias when the list comes around again in 2014.

The final storm to have its name retired in 2008 was also the final storm of the season: Hurricane Paloma. Paloma formed in November, and its winds of 145 mph made it the second strongest storm of the 2008 season in the Atlantic, and also the second strongest hurricane ever observed in the Atlantic during the month of November. Unlike the other hurricanes of 2008 to earn retirement, Paloma is not responsible for any fatalities. However, the damage in the Cayman Islands was severe. Nearly every building on the island of Cayman Brac was damaged or destroyed when Paloma made a very close pass at near-peak intensity. Damage was also widespread on the island of Little Cayman. Paloma went on to strike Cuba at Category 3 strength, being the fourth major hurricane of the season to hit the island nation. The name Paloma has been retired from the 2008 list, and will be replaced by Paulette when the list comes around again in 2014.

In terms of total storm retirements, the letter C still leads the way with 9 retired names. The letter F is second with 8, but I has climbed into a tie for third with D, each having 7 names retired. Paloma becomes the first P storm to be retired. Only the letters T and V have not had any storms retired (T was only used once, in 2005, and Tropical Storm Tanya fell well short; V has also been used only once, in 2005, and Hurricane Vince was notable but not worthy of retirement).

Eye Candy for Weather Geeks

Every now and then, we see something in the course of our daily work that captures our attention and brings out the inner "weather geek". We enjoy seeing cool things that make us go "Ooooh... what is that?" and take a closer look. Today we found three such things; two are interesting looking even to casual weather observers, while the third is a sight for sore eyes in parts of California where the air conditioners have been working hard lately.

We begin with this item, seen on visible satellite imagery at left moving across northern Missouri (click to open a full-size version of the image in a new window). Astute observers will notice that the swirl of clouds bears some resemblance to a developing tropical storm, with the central mass of convection but most notably with the spiral band of clouds on the northern semicircle, extending from northwestern Missouri, up through Iowa, and then from there southeastward across northern Illinois.

What we're seeing here is not a tropical cyclone, even though it might look a little like one. This is an ordinary complex of thunderstorms, called a mesoscale convective system (MCS). What makes this MCS so special is its well developed swirl (which is clear in satellite and radar animations, which, sadly, we cannot reproduce here). The small scale circulation within an MCS is known as a mesoscale convective vortex, or MCV. Not all MCS's can generate MCV's, but once the MCV is present it can help sustain the thunderstorms as the complex moves along. Occasionally the MCV can help spawn tornadoes, but this is not common. This particular MCV is very pronounced.

The other feature of note in this thunderstorm complex is the high level outflow. This is manifested in the spiral band of high clouds on its northern side that we touched on earlier. Well developed MCS's will sometimes develop the MCV, the counterclockwise circulation at the low and mid levels, but at higher levels the circulation reverses and becomes clockwise. Satellite animations make this clear; the thunderstorms within the complex exhibit some counterclockwise turning, but the high level outflow exits the system in a clockwise fashion. This is thermodynamically very similar to a tropical storm or hurricane, which have the usual counterclockwise flow at low levels, with clockwise outflow aloft. This similarity has led some meteorologists to casually refer to MCS's like this as "landphoons."

The next item on the list may require some readers to turn their monitors upside-down, since it comes to us from the Southern Hemisphere. It is Autumn for our friends down under, and the tropical season is still ongoing although the end is approaching. The item of interest (you'll probably need to open the full-size version of the satellite image at left in a new window) is near the right edge of the screen. We're looking at the swirl of clouds and showers located between the east coast of Australia and New Zealand.

This system began about a week ago when a common storm system stalled over the Tasman Sea. The center of the storm became cutoff as its upper support moved on, leaving behind what meteorologists refer to as a "stacked" area of low pressure: a low at the surface, with an upper level low right above. In most cases, vertically stacked lows tend to weaken. However, if the stacked low is stalled, and it is sitting over an area of moderately warm ocean waters, and the upper level low is strong enough and cold enough, the atmosphere can gradually destabilize and thunderstorms can form. The vertically stacked low provides an environment of reasonably low wind shear, and low wind shear plus thunderstorms plus an established cyclonic (clockwise in this case since we're in the Southern Hemisphere) circulation is a recipe for an uncommon type of tropical development: the subtropical or "hybrid" storm.

We've seen cases like this before (last season, Tropical Storm Laura in the Atlantic had subtropical origins; the "perfect storm" of 1991 in the North Atlantic is an extreme example). However, the scenario that seems to be most like this current case is the 2004 tropical cyclone which formed off the coast of Brazil in the South Atlantic. In both cases, a stacked low pressure stalled over marginally warm ocean waters, and in time developed convection and found new life as a tropical entity.

In any event, the cyclone (Tropical cyclone? Subtropical cyclone? Hard to say for sure.) in the Tasman Sea has not been officially designated as a tropical or subtropical system by the responsible parties (the Australian Bureau of Meteorology office in Brisbane, or the New Zealand Weather Service in Wellington), although there are gale and storm warnings for mariners in the area. The storm, which has been slowly making a clockwise loop over the past week, is expected to drift south and then southeast, where it should get picked up by the main belt of westerlies in the Southern Hemisphere. As it gains latitude, it will lose whatever tropical characteristics it has managed to cobble together. It may bring gusty winds to New Zealand's South Island this weekend, but mainly this system is just a meteorological curiosity and not a significant threat.

The last item of meteorological eye candy is far less dramatic than the "landphoon" or the hybrid/subtropical storm, but for residents of California it is the welcome return of an old friend. Earlier this week, numerous record highs were set in California as a strong upper level ridge built in over the region. The combination of warm temperatures aloft and offshore flow spelled heat for the coastal regions. Temperatures in the valleys surrounding Los Angeles reached over 100. San Diego checked in with 98 degrees and even San Francisco got up into the 90s during the hot days. Now that the upper ridge has moved on, a more typical regime has returned to California, and you can see it in the satellite image we have at left (click to open a full-size version in a new window).

The marine layer off the West Coast is the layer of air in contact with the cool Pacific waters. It is usually cool and somewhat damp. When the marine layer is present, it usually sweeps inland at night to blanket the coastal areas with cool air, low clouds, and sometimes fog. During the day it retreats and breaks up. This diurnal cycle of the marine layer leads to the typical Southern California forecast in May and June: late night and early morning low clouds and fog, clearing by afternoon. With the upper ridge gone, the marine layer has returned. It can be seen in satellite images by the blanket of low clouds that hugs the California coast and has pushed inland several miles.

As seen in our image, the marine layer has pushed exceptionally far inland over Southern California. Almost the entire Los Angeles Basin is shrouded by the low clouds and fog, including several valleys well inland from the coast. The cool maritime air, with temperatures only in the 60s across much of the Basin, provides welcome relief and stands in sharp contrast to the temperatures of a few days ago which in some cases were higher by almost 40 degrees.

Deadly Tornadoes in the Southeast

An outbreak of severe thunderstorms struck the south-central and southeastern U.S. last week. An unseasonably strong and dynamic upper level storm developed over western Oklahoma and pushed east-northeast across the lower Mississippi Valley and on toward the Tennessee and Ohio Valleys. Severe thunderstorms produced abundant reports of hail, damaging straight line winds, and tornadoes. Some of the tornadoes that affected the region on April 9 and 10 proved to be deadly.

Severe thunderstorms initially erupted in eastern Oklahoma on the evening of April 9. The first tornado was reported in the northeastern corner of the state, but the more significant and long-tracked tornadoes developed in the southeastern part of Oklahoma as well as adjacent extreme northeastern Texas, before trucking along into Arkansas and Louisiana. The most damaging storm of the day struck the mountain town of Mena in far western Arkansas. Rated EF3 on the Enhanced Fujita Scale, this tornado did substantial damage to the city center and has resulted in 8 fatalities thus far. Another EF3 tornado struck farther to the south near the town of Dierks, and a third EF3 affected Miller County. The Shreveport-Bossier City metro area in northwestern Louisiana was also affected by tornadoes during the event. In all, a total of 19 tornadoes from April 9 have been confirmed by National Weather Service survey teams. Of these, 5 were rated as EF2 (strong), to go along with the 3 tornadoes rated EF3 (severe). In addition, there were also 103 reports of damaging straight line winds (58 mph or greater), and 151 reports of severe hail (0.75 inches in diameter or larger).

As the storm system advanced east on Friday, April 10, the afternoon heating generated enough atmospheric instability to spark another round of severe thunderstorms and tornadoes. These storms affected areas of Kentucky, Tennessee, Mississippi, Alabama, Georgia, South Carolina, and North Carolina. The most significant storm of the day laid waste to a part of Murfreesboro, Tennessee with an EF4 tornado that claimed two lives and caused an additional 42 injuries. Five more EF3 tornadoes raked the region, to go along with two EF2 tornadoes. A total of 32 tornadoes have been confirmed across the seven states so far from April 10.

The preliminary totals from this two-day outbreak of severe weather:
51 total tornadoes
- 7 EF2 (strong)
- 8 EF3 (severe)
- 1 EF4 (devastating)

214 straight line wind reports
- 2 significant (greater than 74 mph)

419 severe hail reports
- 29 significant (greater than 2" in diameter)

A potentially greater threat is evolving in the southern Georgia and northern Florida. Rivers are already running very high thanks to a widespread heavy rain event last week. Additional rains fell over the weekend during the severe weather episode, and now today another heavy rain event is taking place. Rivers such as the Suwannee and Withlacoochee are in major flood and record flooding is becoming a very real threat with the continued rains. US Highway 90 is already closed in the area due to flooding, and there is a risk that Interstate 10 may be forced to close as well.

The Return of Winter

The past couple of weeks have been a very busy time in terms of winter weather in the Plains states. Several notable winter storms have affected areas from Texas to the Dakotas, at times accompanied by very chilly temperatures for this time of year.

The first event in the period of active weather in the Plains commenced on March 23 with a blizzard on the northern High Plains. Snow totals of 6 inches or more were common all throughout the Dakotas, with 8" at Bismarck, and nearly a foot of new snow in Rapid City (where the high temperature the previous day was 77 degrees!).

In the second act, the scene shifted to the southern Plains. A potent and cold upper level low with origins in the Gulf of Alaska advanced quickly southeast across the Rockies and emerged into the southern High Plains on March 26. The compact but powerful system produced a quick 8 inches of snow on the 26th. Tapping into Gulf moisture while intensifying, the system generated heavy snow and strong winds - a veritable blizzard. During the storm, Amarillo, Texas received 11 inches of snow, with amounts closer to 14 inches to the north in Dalhart and in Guymon, Oklahoma. Dodge City in southwestern Kansas measured 12 inches of snow. Unofficial totals of 24-28 inches of snow came in from northwestern Oklahoma around Fort Supply, extending in a band in southern Kansas through Coldwater and Pratt. The larger Wichita metro area received 7 inches of snow and Oklahoma City just 2 inches. The strong winds of the storm resulted in severely reduced visibilities and considerable blowing and drifting of snow. Dodge City reported snow drifts as high as 6 feet, with up to 14 foot high drifts near Dalhart.

On the morning of March 28, the storm generated a new band of heavy precipitation which stayed over the Tulsa metro area and adjacent northeastern Oklahoma for much of the day. Intense snowfall accompanied by thunder and lightning persisted through the morning, with the rapid accumulations of heavy, wet snow causing damage to trees that were in various stages of bloom. Scattered power outages were also reported. In total, Tulsa received almost 10 inches of snow - more than what the city gets on average in an entire year!

After relative calm for a few days, another snowstorm took aim on the northern Plains toward the end of March. On March 30, another 12 inches of snow slammed into Rapid City. Impacts further to the south were less than in the snowstorm of March 23 (Denver only received 3 inches), but more severe to the north (Bismarck received an unwanted 17 inches of snow during the event). And almost like clockwork, another blizzard affected the northern Plains this past weekend, dropping yet another 12 inches of snow in Rapid City.

This most recent snowstorm in the Plains tapped into a reserve of particularly cold Canadian air. At this writing, the much colder than normal temperatures were pouring into the Plains on stiff northerly winds, sending temperatures 10-20 degrees below normal. With afternoon highs stuck in the 40s across much of the central Plains on Monday, and clear skies and light winds expected overnight, a widespread freeze is anticipated this evening extending from northern Texas eastward to the Ohio an Tennessee Valleys.

Since the growing season is underway in many of these regions, tonight's freeze could be particularly damaging. Several hours of subfreezing temperatures are expected overnight. Many locations could set new record lows for the date, or even flirt with the all-time record lows for the month of April. A similar hard freeze occurred in almost these same regions two years ago which did result in some damage to trees, young crops, and other sensitive vegetation.

Eruption at Redoubt Volcano in Alaska

A sequence of eruptions began Sunday night at the Redoubt volcano in Alaska. Located about 100 miles southwest of Anchorage on the western side of the Cook Inlet, Redoubt has been under close observation all winter long by the Alaska Volcano Observatory. After a minor eruption on March 15, a series of at least five explosive eruptions occurred starting on the evening of March 22.

The eruptions at Redoubt produced an ash cloud extending well up into the atmosphere. Earlier eruptions produced ash clouds extending up to 15,000 feet, but subsequent and more vigorous eruptions emitted ash up to 50,000 feet. Volcanic ash is composed of very fine particulates, which can foul electronic and mechanical devices. Ash clouds pose extreme aviation risks. Shortly after Redoubt erupted in 1989, a 747 airliner had all four engines fouled by the ash. After losing several thousand feet in altitude, and finding clearer air, the pilots were able to restart the engines and landed safely in Anchorage. Currently there are some flights that have been delayed or diverted around the Anchorage International Airport.

As the ash settles, it can rain down on the surface like a very fine snow. Volcanic ash is an eye and skin irritant, and can also cause respiratory problems. Ashfall advisories have been issued for areas to the north and northeast of Redoubt, where up to a quarter inch of ash has accumulated in some areas.

Volcanic eruptions that spew ash to high altitudes can have an effect on the regional and sometimes the global climate. The most recent example was the eruption of Mount Pinatubo in the Philippines in 1991. Pinatubo's eruption is an extreme example, as it ejected a large volume of particulates and aerosols high into the atmosphere, and its tropical location allowed the ash cloud to disperse into both the northern and southern hemispheres. The ash from Pinatubo blocked incoming sunlight, which led to a global temperature drop of about 1 degree Fahrenheit in the following year. The current eruptions at Redoubt were not nearly as large as Mount Pinatubo's 1991 cataclysm, and given Redoubt's far northern location, it does not appear that there will be any great effects on the climate - barring any additional large eruptions.

For latest updates on the ongoing eruptions at Redoubt, we recommend visiting the Alaska Volcano Observatory's recent activity page for the Redoubt volcano.

Drought Status Update

Spring has brought copious rains to portions of the nation, while others continue in want of precipitation, languishing in drought.  While the catastrophic flooding in parts of the Midwest draws much of the media attention (and deservedly so), we thought we'd check in on other parts of the country.

We begin, as usual, with the latest edition of the U.S. Drought Monitor, which comes courtesy of the National Drought Mitigation Center in Lincoln, Nebraska.  The map at left (click to open a full-size version in a new window) shows the areas of the country that are either approaching drought, or are already in drought.  Drought severity is ranked on a 5 point scale, from D0 (abnormally dry) through the most severe D4 (exceptional drought).

The good news about the current drought situation across the country is that there are no areas of D4 drought.  However, there are several regions in the grip of an extreme drought (rated D3).  These include the highlands of the western Carolinas and northeastern  Georgia; parts of North Dakota; the old Dust Bowl region where Texas, New Mexico, Colorado, Kansas, and the Oklahoma panhandle meet; and parts of the Rio Grande valley in southern Texas.  Severe drought (D2) is also noted in parts of the West, as well as additional areas in Texas, the Southeast, and also in south Florida.

A relatively new feature of the U.S. Drought Monitor is the ability to zoom in on particular regions and states.  As an example, we show the state drought map for North Dakota at left.  In addition to delineating the drought areas in greater detail, the state map is also accompanied by a table that shows the estimated area of the state that falls into each drought category (as a percentage), and also how these areas have changed over time.  The current table of statistics shows that approximately 29% of North Dakota's area falls into D3 drought.  This is an improvement over last week, when 38% of the state's area was in extreme drought, but a decline since March when only 6% of the state fell into the D3 category.

The Drought Monitor also provides maps that show how the drought classifications have changed over time, from periods ranging from 1 week, to 1 month, to the entire water year (since October 1).  At left is the 4-week change map.  The areas shaded in green are drought regions that have improved by at least one category (e.g., an upgrade from D3 to D2).  Areas colored in brown are drought regions where conditions have deteriorated by at least one category (e.g., from D1 to D2).  The yellow areas are where the ongoing drought has not changed in category.

The 4-week change map shows that improvements have taken place across Montana and much of the northern High Plains, and also in parts of the Southeast where the recovery from the recent exceptional drought gradually continues.  Other parts of the Southeast have seen little improvement or in some cases, even a worsening of drought conditions.  Parts of southern Texas have also seen a dramatic deterioration - by as much as three whole categories - over the past month.

It is often said that there's always a drought somewhere in the country.  The change map for the water year (shown at left) supports that saying.  Since October 1, 2007, the droughts across the West and the Southeast have, in general, seen improvement.  The areas shaded in blue over Tennessee and Kentucky stand out in particular.  These are areas that have seen a four category improvement in their drought status, and much of these two states is now completely recovered and not in drought at all.  But as the droughts in the Southeast and West eased, new drought cropped up in the south-central states and also in North Dakota.  Parts of Texas and southern New Mexico have been quite dry, and drought conditions there have degraded by as much as four categories.

Looking ahead through summer, there are many areas where the current droughts are forecast to improve.  The latest drought outlook, produced by NOAA's Climate Prediction Center and shown at left, paints a good news-bad news scenario.  Many of the drought areas east of the Rockies can look forward to some improvement (denoted by areas shaded in green, or in brown with green hatching).  In the Southeast, this is due to the upcoming onset of the season with daily chances for afternoon showers.  In the northern Plains, the opportunity for more rain increases heading into July as the jet stream and storm track migrate into the region.  The forecast is less optimistic for the West however.  With the dry season continuing, California will have little opportunity for rain for the next couple of months, and as a result drought conditions there are likely to expand and worsen (shown by the yellow and brown shading).

Drought Status Update

Drought conditions have continued to improve across much of the western U.S. thanks to a recent active and wet pattern. Even portions of southern California are doing quite well this winter in terms of precipitation relative to normal.

The image at left is the newest edition of the U.S. Drought Monitor (click on the image to open a full-size version in a new window). Based on a variety of meteorological and hydrological indices, and refined with input from state and local agencies, the Drought Monitor provides a clear synopsis of the locations and severity of droughts in the U.S. Severity is rated on a five point scale from zero to four.

The new drought monitor indicates that the worst drought conditions continue to be in the Southeast. An area of exceptional drought (D4 - the highest classification) remains in northern Alabama, eastern Tennessee, and northwestern Georgia, with a second area of D4 drought in North Carolina. 26.3% of the area in North Carolina is in the throes of D4 drought, with all of the state save for a small area near Cape Lookout in at least moderate drought. 25% of the state of Georgia, including the northern half, is in extreme drought or worse; and in Alabama over 40% of the state is in D3 or D4 drought.

In addition to the woes in the Southeast, drought conditions are also ongoing in the West and the High Plains. In the West, much of the Great Basin is in severe drought. Almost 60% of Nevada's land is in D2 level drought. The severe drought also extends through the Snake River Plain in Idaho, and also to the Great Salt Lake area in Utah. In the High Plains, severe drought covers parts of Nebraska and the Dakotas, and further to the south an area of severe drought is located in the lower Rio Grande valley of Texas. Isolated pockets of extreme drought are noted within the larger D2 area as well.

The map at left shows how the drought classifications have changed during the past four weeks. Areas shaded in yellow are drought areas that have seen little improvement. Brown areas are regions where drought has gotten worse during the past month, and the green shaded areas are areas where the drought classification has improved by at least one category (i.e., D3 to D2).

Drought improvements during the past month have been most noticeable in the Southeast. Here, improvements of at least one category have occurred over large parts of Mississippi, Alabama, Florida, and Georgia. Some relief has also taken place in the Carolinas. California and the West have also fared well in the recent weeks. A wet pattern has brought a one-category improvement to southern California, meaning much of the heavily populated areas of Los Angeles and San Diego are now no longer officially in drought anymore.

In some places though, the drought has worsened during the past month. Portions of the northern Plains have seen drought conditions deteriorate by one category. Texas in particular has seen conditions go downhill recently. A continued lack of rainfall, coupled with episodes of dry and windy weather, has led to the drought there intensifying by one to two categories.

Our final map is the outlook for the next three months, released by the Climate Prediction Center. The areas shaded in brown are the current drought areas, which are forecast to see drought continue or worsen. Areas shaded in yellow are regions that are not currently in drought, but where the development of drought is possible. Green areas are current drought regions that are forecast to see improvement of at least a category, and the brown areas with green hatching are areas of ongoing drought where a lesser degree of improvement is expected.

From the outlook, we can expect a continuation of dryness in Texas and Florida, and an expansion and worsening of the ongoing droughts there. Additional improvement is forecast for the heavily impacted areas of the Southeast. Improvement is also expected in the Great Basin, and to a lesser extent, in the northern High Plains.

The Snowy Winter (For Some) of 2007-08

The winter of 2007-08 has been one of variability.  We've seen temperatures in the Lower 48 oscillate between well above normal and much below normal and back again - sometimes within the span of a few days!  For many areas of the country, 2007-08 has been a wet winter so far.  We've seen numerous heavy rain events, and already many parts of the Midwest have been dealing with flood problems from the combination of unseasonably heavy rain and melting snow.  The big winner in terms of publicity this winter has been Madison, Wisconsin, which set a new record for snowfall in a season - and the season isn't done yet!  Many other parts of the country are also doing well in terms of snowfall this winter, and we present a recap of the snowfall totals to date.

West

So far, the western U.S. has done fairly well with precipitation this season.  Even parts of perennially dry southern California have picked up beneficial rain and mountain snow and are keeping pace with the normals this winter.

City		Snowfall to Date	Departure from Normal

Salt Lake City	  60.9			  +16.8
Alamosa		  30.6			  + 9.8
Flagstaff	  67.9			  + 2.6
Great Falls	  33.6			  - 2.5
Cheyenne	  27.1			  - 6.1
Colo. Springs	  18.0			  - 7.3
Reno		  15.8			    N/A
El Paso		   7.7			    N/A

Midwest

Much of the Midwest has done quite well with snow this winter.  The highlight has been in a swath from Iowa through southern Wisconsin and northern Illinois where snowfall to date is far ahead of normal.  On the flipside, some parts of the upper Midwest and upper Ohio Valley are running behind the seasonal normals.

City		Snowfall to Date	Departure from Normal

Madison		  86.7			  +50.5
Milwaukee	  76.8			  +38.1
Des Moines	  48.4			  +21.6
Chicago		  45.4			  +17.9
Kansas City	  23.1			  + 7.7
Detroit		  38.7			  + 6.4
Omaha		  21.5			  + 2.1
Fort Wayne	  28.1			  + 1.0
St. Louis	  16.9			  - 0.5
Marquette	 128.1			  - 0.7
Indianapolis	  17.5			  - 4.1
Columbus OH	  17.5			  - 4.2
Pittsburgh	  24.0			  - 4.5
Cincinnati	   9.4			  - 7.8
Duluth		  50.0			  - 8.9
Cleveland	  31.7			  -13.1
Minneapolis	  24.1			  -15.2
Wichita		  21.0			    N/A
Tulsa		   3.1			    N/A

South

Not typically a very snowy region of the country, it's not surprising that most cities in the South are running behind their normal snowfalls by this date.

City		Snowfall to Date	Departure from Normal

Atlanta		   1.4			  - 0.4
Dallas		     T			  - 2.4
Charlotte	   1.4			  - 3.6
Little Rock	     T			  - 4.2
Memphis		     T			  - 5.2
Nashville	   0.5			  - 6.4

East

The eastern U.S., in some ways like the Midwest, has also been a study in contrasts when examining the snowfall totals so far this winter season.  Most of the interior and northern areas, particularly New England, have done quite well so far this season, while areas closer to the coast such as the major northeastern cities, have seen less snow.

City		Snowfall to Date	Departure from Normal

Caribou ME	 137.6			  +58.8
Concord NH	  86.8			  +40.8
Burlington	  93.0			  +36.5
Portland ME	  79.0			  +32.8
Boston		  40.7			  +11.1
Worcester	  48.9			  + 6.7
Albany		  44.8			    0
Washington DC	   3.9			  - 8.1
Philadelphia	   2.9			  -10.6
New York City	   4.6			  -12.1
Buffalo		  60.5			  -14.4

Super Tuesday Outbreak

An historic outbreak of severe weather - including numerous long-tracked and violent tornadoes - struck parts of the South and the Ohio Valley last Tuesday.  Coincident with the Super Tuesday presidential primaries, this outbreak has been dubbed the "Super Tuesday Outbreak."  Tornadoes hit metropolitan Memphis and Nashville, while widespread wind damage raked Kentucky.  Additional tornadoes also hit in Arkansas, including one extremely long-lived storm.

The outbreak was fueled in part by the unseasonably mild and humid air that had overspread the central U.S. in the days leading up to the event.  Numerous record highs were set, with many areas enjoying afternoon temperatures in the 60s and 70s, almost 30 degrees warmer than normal.  With that degree of heat and moisture present, strong and dynamic storms can spawn massive outbreaks of severe weather.  We saw it in January with the storm that brought deadly tornadoes to Missouri.

It's actually not all that uncommon to see severe weather outbreaks in the South during the late winter.  When the climatological threat of severe weather fades away in the traditional areas of Tornado Alley in Fall, it retreats to the South where a small but nonzero probability of severe weather exists through much of the winter months.  While the threat is indeed small, and outbreaks are not an everyday occurrence, according to climatological threat maps from the National Severe Storms Laboratory (NSSL) the area most likely to experience severe weather during January and February is indeed the South.

The event summaries listed below provide a comprehensive report of the events that took place during the Super Tuesday Storm on Feb. 5-6.   So far, 63 tornadoes have been confirmed during the two days.  Of those, 24 were strong to violent tornadoes (rated EF2 or higher).  Personally, three things stand out about this outbreak:

1. Major metropolitan areas hit.  In addition to the greater Memphis and Nashville regions, tornadoes also threatened Huntsville, Louisville, and Lexington.  Forecasters at the National Weather Service office in Memphis, who were issuing the life-saving tornado warnings for eastern Arkansas, northern Mississippi, and western Tennessee, found themselves under the gun and were forced to take shelter for a time.
2. Jackson, Tennessee struck yet again.  The city of Jackson has become Tennessee's capital when it comes to violent tornadoes.  On Super Tuesday it was hit by a family of tornadic thunderstorms that spawned three tornadoes in the area - two EF3 and one EF4.  This most recent storm marks the third time in less than 10 years that Jackson has been hit by violent tornadoes rated F4/EF4 (the others were January 17, 1999 and May 4, 2003).
3. The extremely long-tracked Atkins-Clinton tornado in Arkansas.  This tornado, rated EF4, was on the ground continuously for approximately 123 miles in central and northern Arkansas.  As if its long track weren't enough to make it noteworthy, the tornado passed through some of the most heavily wooded and rugged portions of the Boston Mountains.

In all, there have been 59 deaths confirmed from the tornadoes.  The deadliest single tornado of the outbreak was the Nashville storm, which claimed the lives of 24 people to the northeast of the capital city.

For additional information, we recommend:

• NSSL Severe Weather Climatology - includes a large collection of maps showing the climatology of severe weather and tornadoes in the U.S.
• Event Summary from the Storm Prediction Center - includes preliminary storm reports, as well as links to the outlooks and watches issued by the SPC during the event.
• Wikipedia's article on the Super Tuesday Outbreak, including damage and casualty statistics and tornado EF-scale ratings, plus links to regional National Weather Service event summaries.

Drought Status Update

The recent period of exceptionally mild temperatures in January also brought with it unseasonably humid air as well.  Much of this excess moisture was "cashed in" in the form of rain and snow across much of the eastern half of the country.  While some of this was accompanied by severe thunderstorms and some tornadoes, in many places the rains left behind by the storms have helped ease drought conditions.

The newest edition of the U.S. Drought Monitor map is shown at left (click to open a larger version in a new window).  The U.S. Drought Monitor is a bulletin released weekly by the National Drought Mitigation Center at the University of Nebraska in Lincoln, NE.  The Drought Monitor synthesizes recent temperature and rainfall data, soil moisture conditions, flows in rivers and streams, lake levels, snowpack, along with local and regional agricultural conditions from farmers and ranchers, and produces a comprehensive map showing the regions currently being affected by drought.  The Drought Monitor rates the seriousness of a drought on a 5 point scale:  D0 is the lightest category and is used to indicate areas that are not yet in drought, but have been unusually dry recently.  D1 indicates moderate drought, D2 is severe drought, D3 is extreme drought, and the highest category is D4, for exceptional drought.

A recent addition to the Drought Monitor is the set of regional and state maps.  By clicking on a specific state or region, you can zoom in to a more detailed map which also presents statistics on the areal drought coverage and recent changes.

The most stricken area of the country remains the Southeast.  2007 finished as a very dry year across much of the region.  Atlanta was saved from recording the driest year on record by a late December storm, but still finished the year with a rainfall deficit of 18.35 inches, 37% below the total average annual rainfall.  Much of Alabama, as well as northern Georgia and portions of Tennessee and the Carolinas remain in D4, the most severe drought category.  38.9% of the area in Alabama and 46% of North Carolina are classified as D4.  The cities of Atlanta, Charlotte, and Raleigh are included in the D4 region.

Surrounding the exceptional drought area is still a large area of extreme drought.  An additional 37.5% of North Carolina's area is suffering from D3 drought, which makes a total of 83.5% of the state that is in extreme or worse drought.  All of North Carolina is rated D2 or worse.  41.9% of South Carolina is D3 or worse, as is nearly half of Georgia and 55.6% of Alabama.

Other areas of the country experiencing extreme drought are portions of the Florida peninsula, including much of the citrus growing region, as well as a portion of northwestern Nebraska.

The other region of the country experiencing drought issues is the West.  It's the rainy (and snowy) season there, so much of the mountainous West is adding snowpack, with rains in the lower elevations.  Nevertheless, much of the West remains in moderate and severe drought.  87.7% of Nevada is in D2 drought, with the remainder of the state in D1.  In California, 32.8% of the state is in severe drought, which includes some portions of the San Joaquin Valley as well as much of the L.A. Basin.  Moderate drought covers an additional 47% of the land in California, including the remainder of the San Joaquin Valley and southern California, plus much of the Sacramento Valley.

Although the droughts remain severe or worse in the Southeast and West, some improvement has occurred during the past month.   The map at left (click to open a full-size version in a new window) is a map produced by the Drought Monitor showing the changes in classification during the past four weeks.  Areas shaded in yellow are drought areas that have seen little to no improvement.  The green-shaded regions in the Southwest and Southeast are areas in drought that have seen an improvement of one category (i.e., from D3 to D2).  The areas in brown are areas where drought has worsened.

Looking ahead for the remainder of Winter into the first part of Spring, there is some cause for optimism.  The map at left shows the outlook for the drought regions that is produced by the Climate Prediction Center.  At least some improvement is expected heading into April for much of the drought regions of the West and Southeast.  Less in the way of rainfall is expected in the Desert Southwest, much of  Texas, and parts of south Florida as well, where the current droughts are forecast to either persist or expand.