Baked Alaska

While most of the lower 48 states were generally enjoying typical summer weather this week, Alaska residents suffered through a record-setting heat wave. It was just one month ago Tuesday that Anchorage had its last measurable snow.

The record heat was the result of a very strong ridge of high pressure in the upper atmosphere. The center of this "closed" high was located right over Alaska. Within the high air descends and warms, keeping skies clear allowing full sunshine. The high also moved very little during the last several days keeping any weather systems that might have brought relief at bay.

Upper level map (500 millibars, about 20,000 feet) showing the strong ridge over Alaska.

June 17 satellite image of Alaska showing cloud-free skies. Since Alaska is surrounded
by water, cloud-free days, especially over most of the state, are rare. Credit:  NASA

Here are the records set as of Tuesday.

All-time records set on Monday, June 17

Records for Tuesday, June 18.

One of our Alaskan CoCoRaHS observers included comments about the heat in his observations this week. The station is AK-MS-11, Palmer 1.7 WNW, located about 40 miles northeast of Anchorage.

June 17
Hot, dry weather has produced the warmest high temperature I have recorded in nearly nine years of record keeping in Alaska. Yesterday I reached 81.4° F and cooled only to 59.6° F, my warmest overnight low in nearly nine years. Winds reached 20.6 m.p.h. early in the evening which provided some relief. Today may be even hotter as winds are presently light and skies are clear.

June 18
Sunny, hot weather drove my high temperature in Palmer to a phenomenal 83.9° F and increased winds overnight prevented it from dropping below 65.7° F for the overnight low. My maximum gust earlier this morning was 41.2 m.p.h. A high cloud layer has developed this morning giving partly cloudy skies and the wind is continuing.


Residents headed out to beaches and parks seeking releif from the heat and/or just taking advantage of the unusual summer weather. Stores sold out of fans. Those who didn't have fans had to endure, as air conditioning is not common in most homes in Alaska.While for most of us here in the lower 48 an 81°F day is pleasant in the summer, it's a record in Anchorage. The heat also brought out the mosquitoes in large numbers, with some residents calling it the worst they have ever seen.

Fortunately for Alaskan residents the weather will be moderating this week. High temperatures in Anchorage, for example, will be in the 60s to low 70s into the weekend.

ET - Moving Water Back into the Atmosphere

If you Google "ET" or "E-T" the first several results returned are for the 1982 movie E.T. - The Extra-Terrestrial, about a boy who befriends an extra-terrestrial stranded on Earth.  The "ET" that is the subject of this article isn't about visitors from outer space, but it is a concept that may be a little "alien" to many people.

ET stands for evapotranspiration, the process in which water vapor moves back into the atmosphere.  Evapotranspiration is the sum of evaporation from ground surfaces and the transpiration of water to the atmosphere from plant leaves.  ET is a function of temperature, wind speed, relative humidity, and solar radiation. Transpiration occurs when the roots of a plant draw moisture from the soil where it moves up through the plant to be released as water vapor from the leaves. On average more than half the precipitation that falls is returned to the atmosphere through ET.  Studies show that transpiration by vegetation accounts for about 10 percent of the moisture in the atmosphere.  An acre of corn can transpire about 3,000 to 4,000 gallons of water per day.  The transpiration from agricultural crops is often significant enough contribute to the higher dew point temperatures that create muggy conditions during the summer and may enhance the formation of showers and thunderstorms.  Conversely, the reduction in transpiration, such during drought, reduces the return of moisture to the atmosphere which in turn inhibits the development of showers and thunderstorms.

The E-T Gauge

CoCoRaHS observers measure what falls out of the atmosphere, precipitation. Beginning last year, however, a number of CoCoRaHS observers have been measuring evapotranspiration, or what is going back into the atmosphere, the "return" side of the water cycle.  Evapotranspiration measurements actually began in mid-2011 with a few volunteers as a pilot project. Last spring the opportunity to make ET measurements was opened up to the observers at large. At present there are about 90 observers in 38 states making ET measurements across the country along with their rainfall (or in many cases, lack of rainfall) measurements.   ET does not vary to the same extent as precipitation (it's more similar to temperature), so multiple measurements in the same general area are usually not needed, unlike precipitation. ET measurements are only made during the warm season, since freezing temperatures can damage the gauge.



The measurements are made using a special ET gauge developed for this purpose.  The gauge consists of a water reservoir, with a cap consisting of a ceramic evaporator surface with a green fabric cover.  In our case the fabric simulates evaporation over turf, so the gauge needs to be sited in a sunny, exposed area and preferably over grass.  We are measuring "reference ET" which is defined as "the ET from an extensive surface of clipped grass… that is well-watered, and fully shades the ground."  This reference ET is referred to as ETo . Another cover is available which simulatesevaporation over alfalfa (ET1). The cap is connected to a supply tube which extends the length of the reservoir. There is a sight tube on the exterior of the gauge which measures the water level in the gauge.  The difference in water level from one observation to the next represents the evapotranspiration.


The measurement of both precipitation and evapotranspiration allows us to calculate an atmospheric water balance.  Water balance charts are available on the CoCoRaHS web site (I also had one in my last blog post about New Mexico). This plots precipitation, ET, and the accumulated difference over time.

Water balance chart for ME-CM-3, located about 20 miles north of Portland, Maine.

Water balance chart for TX-ER-4, about 60 miles WSW of Fort Worth, Texas

Water balance chart for UT-ML-1, about 80 miles SSW of Salt Lake City

 
These charts provide a good sampling of the relationship between ET and precipitation and the water balance. When viewing ET charts, keep in mind that the charts do show multi-day ET values (total E-T over a period of more than a day), but the charts don't plot multi-day precipitation accumulations. Only daily reports are reflected on the charts.

The measuring of ET is relatively easy but there is a commitment of time and money.  The ET gauges cost about $220, and there is a little more to setting up and maintaining them.  However, the ET measurements are very useful and more importantly fill a big data need. Most estimates of ET are calculated, and the deployment of these gauges to CoCoRaHS observers represents the first organized effort to measure ET other than in automated, specialized networks.

For more information on evapotranspiration and the CoCoRaHS measurement program, visit the CoCoRaHS web site and select Evapotranspiration in the Resources menu of the left side of the page.

New Mexico in 2013 - Land of Dessication

New Mexico's official "nickname" is the Land of Enchantment. It really is a beautiful state, rich in natural beauty and cultural heritage. One of my lasting memories of a vacation out west years ago was while driving through New Mexico during the late afternoon and entering a flat desert plain surrounding by towering mesas. The late afternoon sun combined with the colors of the landscape was an amazing sight.

Unfortunately, New Mexico has become ground zero of the drought that has been in progress over the western U.S. the past two years. A little over 82 percent of the state is in Extreme to Exceptional Drought according to the latest U.S. Drought Monitor. That's the highest percentage of any state currently affected. Conditions have significantly worsened over the last three months.  At the start of the calendar year about 32 percent of the state was in Extreme to Exceptional Drought, and by March it was up to 50 percent.     

CoCoRaHS observers have been documenting the drought impacts, and some of the descriptions sound like they could have come from the Dust Bowl.  Here are two excerpts.

Santa Fe County
We are noticing that wild animals, birds and mammals, are increasingly desperate for water and therefore losing some of their instinctive fear of humans and other predators. The combination of severe drought and smoke from two wildfires nearby is making some mammals panic at times and come toward us rather than flee us when we are outside.

Rangeland in Lincoln County in April,
normally green at this time. Image credit: Twitter

Luna County
Because we've had so little moisture fall from the sky and we've had daily winds from 20 to 65/70 mph at least 80% of the population is suffering from "allergies" we didn't know we ever had! No one around here has a "lawn" of grass...instead we all measure just how deep the sand is now...the folks with the least amount of sand are considered lucky because they have less dusting/sand clean up to do on the inside of their homes. We've been told by a local farmer that he is now having to pay $20.00 for a bale of hay so he is going to have to sell all of his live stock next week - he can't afford to feed them any longer. And, we've heard that the local rancher spent over $100,000.00 in the last nine months trying to keep his cattle heavy enough to get them to market. We know that we haven't seen any of his cattle in our immediate area in the last 4 or 5 months...which means his heard head count is way down. Would you like us to start measuring the sand in our rain gauge rather than waiting for some moisture to land in it?


You can see the worsening of the drought in the water balance summary for a CoCoRaHS station in Bernalillo County in the north central part of the state. The station is NM-BR-56, Tijeras 3.7 N, located a few miles east of Albuquerque off of Interstate 40. This observer is not just measuring precipitation (or lack thereof), but also evapotranspiration (E-T).  It is the only location in New Mexico with this measurement at the time.  The average annual precipitation for this station is 18.54 inches. The annual total for NM-BR-56 in 2012 was 9.80 inches, just 53 percent of normal. So far in 2013 this station has only measured 1.85 inches of rain!  The observer started E-T- measurements on May 15, and since that time has had more than 8 inches of water loss, and no precipitation. E-T rates have been running from 0.25 to 0.45 inches per day, and without rainfall you can see how quickly the deficit accumulates.

Water balance summary for NM-BR-56. Water balance is precipitation minus E-T.

The precipitation shortfall since the beginning of the calendar year is remarkable. All of the areas in red have 20 percent or less of normal precipitation.

Percent of normal precipitation for January 1-June 13, 2013.
The gray area indicates the data is missing for far western New Mexico on this map.
Map from the National Advanced Hydrologic Prediction Service

The large precipitation deficits have had obvious effects on the streamflow in New Mexico. The Pecos River basin is located on the east side of the state.

Hot, dry weather and tinder dry vegetation also translates into a high risk for wildfires. Several wildfires are already burning encompassing about 50,000 acres in total. A new fire was started by lightning in northern New Mexico this afternoon.

Satellite image of two of the wildfires in northern New Mexico.
Santa Fe is located just west of the Tres Lagunas fire.

Speaking of thunderstorms, there has been storms that have actually produced rain, but they have been few and far between. On June 5 thunderstorms covered Interstate 25 near La Bajada in Santa Fe County with 6 inches of hail. The southbound lanes of the Intersate were closed for over an hour until hghway crews could clear away the ice.  As you might expect, the hail piling up on the highway caused several accidents.

New Mexico residents are looking forward to the onset of the summer monsoon season to provide some rainfall, but it certainly won't be enough to make much of a dent in the current drought. The outlook for the summer in the Southwest is for a higher than normal probability of warm and dry conditions persisting.

A CoCoRaHS History of Andrea

Tropical Storm Andrea developed in the Gulf of Mexico last week and moved up along the east coast finally moving well out to sea Saturday. Andrea began losing tropical characteristics on Friday and by late afternoon Friday was extratropical. The low picked up speed and raced northeast along the coast Friday and Saturday. It finally turned out to sea and was absorbed by another low near Newfoundland Sunday.

Here is an animation of the CoCoRaHS precipitation map from Wednesday, June 5 through Sunday, June 9.

7-day precipitation accumulation ending Sunday, June 9. Not all precipitation
along the eastern seaboard during this period was due to Andrea, but
her footprint is certainly evident.

Andrea Poised to Soak Eastern Seaboard

Infrared satellite image at 10:31 p.m. EDT. The center of Andrea is
approximately 30 miles west of Jacksonville, FL.
Image credit: College of DuPage

Tropical Storm Andrea, which became the first named tropical system of the season in the Atlantic Basin yesterday, is currently crossing northern Florida after dumping 2 to 4 inches of rain on the southern half  of the state yesterday and last night. A tornado watch was in effect for much of Florida during the day. There were eight reports of tornadoes, most of which caused some damage.

The rain shield associated with Andrea has now spread north in to Georgia and South Carolina.

Radar image at 10:26 p.m. EDT. The red "L" indicates the center of Andrea.

The rain will continue spreading north as Andrea moves off the Florida coast and then takes a path hugging the east coast over the next several days.

Forecast track for Tropical Storm Andrea

Rainfall amounts from 2 to four inches, with locally higher amounts, are expected along the eastern seaboard from Georgia to Maine.

Rainfall forecast through 8:00 p.m. EDT Saturday, June 8.

CoCoRaHS observers - remember to submit Significant Weather Reports to report heavy rain, flooding, or other storm-related weather. These reports are immediately routed to your local National Weather Service Office. If you are going to be gone for part of the weekend and not able to make an observation be sure to review how to submit a multi-day accumulation if you aren't already familiar with this.  There should be some interesting rainfall maps to look at the next three days.

Hurricane Season 2013 - What's Ahead

Hurricane Andrew, 1992

June 1st marks the start of meteorological summer, and probably more significant for those on the east and Gulf coasts, it's the start of the 2013 hurricane season.The National Oceanic and Atmospheric Administration issued it's hurricane season outlook for 2013 about a week ago.  The bottom line is that this is expected to be the fourth consecutive very active hurricane season in the Atlantic.

The outlook is based on current conditions in the Atlantic basin, expected atmospheric conditions over the course of the season, and model forecasts. The three key atmospheric factors that point to a very active hurricane season are:

• A continuation of the atmospheric climate pattern, which includes a strong west African monsoon, that is responsible for the ongoing era of high activity for Atlantic hurricanes that began in 1995
• Warmer-than-average water temperatures in the tropical Atlantic Ocean and Caribbean Sea
• El Niño is not expected to develop and suppress hurricane formation.

NOAA estimates that there is a 70 percent probability that there will be

    13-20 Named Storms
    7-11 Hurricanes
    3-6 Major Hurricanes (Category 3 to Category 5) [link]

In other words, in all seasons with similar climate conditions to those expected this year, 70 percent of those seasons had activity that fell within the ranges above.

This compares to the official 1981-2010 seasonal averages of 12 named storms, 6 hurricanes, and 3 major hurricanes

How did the outlook verify in 2012?  In May 2012 the NOAA outlook was for 9-15 named storms, 4-8 hurricanes, and 1-3 major hurricanes. The outlook was updated in August to 12-17 named storms, 5-8 hurricanes, and 2-3 major hurricanes.  The actual count for 2012 was 19 named storms, 8 hurricanes, and 2 major hurricanes. The two major hurricanes were Michael, which did not make landfall, and Sandy, which did.

Tracks of the named tropical storms in the Atlantic basin in 2012

For a full-size, high resolution version of this map and track maps for previous years, visit the NHC Data Archive.


The 2010, 2011, and 2012 seasons each had 19 named storms in the Atlantic.

This Atlantic hurricane season outlook will be updated in early August, which coincides with the onset of the peak months of the hurricane season. The greatest frequency of tropical storms occurs in mid-September.

Number of tropical cyclones per 100 years

During the month of June tropical storm formation is favored in the Gulf of Mexico and the western Caribbean.

Here are the names of 2013 storms:

Andrea

Barry
Chanta
Dorian
Erin
Fernand
Gabrielle
Humberto
Ingrid
Jerry
Karen
Lorenzo
Melissa
Nestor
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy


Hurricane preparedness week was May 23-June 1. For more information on tropical storms and how to prepare for them, visit  the National Hurricane Center's Hurricane Preparedness web site.  The site has video and audio presentations in both English and Spanish.

Sloshing Into June

The last seven days have been a wet period from the Pacific Northwest to New England and for parts of Texas.  CoCoRaHS observers have been busy measuring inches of rain in many areas. The first map below shows the accumulated precipitation for the past seven days.  The second map shows the percent of normal precipitation.

Map compiled by the NWS Advanced Hydrologic Prediction Service

The greens to blue and violet colors depict normal to much above normal precipitation.
Map compiled by the NWS Advanced Hydrologic Prediction Service

The heavy rainfall, particularly in the Midwest, has been due to a frontal boundary that has extended from the western U.S. to the east coast. Since the weekend this boundary has been oscillating north and south as upper level waves have moved across the country. South of this boundary the air is warm and humid with dewpoints in the 60s. The warm humid air has fueled showers and thunderstorms along and north of the boundary.

Surface map for 7:00 a.m. CDT Tuesday, May 28, 2013

Over the next few days a much stronger upper level low will slowly move across the northern U.S.

500 millibar forecast map for 7:00 a.m. CDT Friday, May 31, 2013.

Heavy showers and thunderstorms are likely along this boundary once again, with from 2 to 4 inches of rain possible across the northern Plains and the Midwest.

Quantitative precipitation forecast for the 3-day period from 7:00 p.m. CDT May 29 to 7:00 p.m. CDT June 1, 2013.

This will prolong and worsen flooding along rivers in the Midwest. The Mississippi River from Burlington, Iowa south to St. Louis is mostly in moderate flooding at the present time, but with the expected rainfall the river is forecast to be in major flood during the first week of June at most river gauges along that reach.

 This map shows the Maximum Forecast Flood Category through June 7, 2013. 0

More Unusual May Weather

The road to Whiteface Mountain
on Saturday, May 25th.

This weekend saw another round of unusual weather at opposite sides of the country. In NewEngland, a remarkable spring storm dropped 24 to 34 inches of snow in upstate New York on Whiteface Mountain at an elevation of 4867 feet. A strong low pressure system moving through the northeast brought several days of heavy precipitation to northern New York and western Vermont. Precipitation totals for the past six days range from 5 to 9 inches, with the heavier amounts in Vermont. On Saturday the rain mixed with and changed to snow in northern New York and Vermont, with snow accumulating at elevations above 900 feet. Snowfall in Vermont ranged from 1.0 inch at Richford, VT to 18.0 inches at Jay Peak, VT (elevation 3862 feet). Some ski areas were reportedly open for the weekend thanks to the snow.



There was deluge amidst drought this weekend in Texas. Thunderstorms dropped more than a foot of rain on the San Antonio, TX metropolitan area.  Some thunderstorms occurred during the afternoon Saturday, but heaviest rain fell in training nocturnal thunderstorms late Saturday night to early Sunday morning. Here is the CoCoRaHS map for Saturday, May 25 for Bexar County.  San Antonio is located near the center.

The heavy rain caused flash flooding in the San Antonio area, with some streams approach record high flood levels. A new record flood stage was set on the San Antonio River Saturday morning.

River stage observations for the San Antonio River

The rain is sorely need in Texas, where lake and reservoir levels are very low from two years of drought. However, this was definitely too much too fast.  Unfortunately the flash flooding caused three fatalities, caused a roof of an apartment complex to collapse, and inundated many roads.

Moore, Oklahoma Tornado

The 12-month period from May 2012 through April 2013 tallied the  fewest number of tornadoes for a 12-month period since 1954.  There were only seven people killed in that 12 month period, the fewest since 1899. The unusually cool spring weather has been responsible for suppressing the severe weather this year. The switch seemed to be flipped about the middle of this month, however.  On May 15 an EF-4 tornado struck Granbury, Texas north of Dallas and an EF-3 hit Cleburne in Johnson County. There have been tornadoes reported on every day since, with 30 tornado reports yesterday, and so far 15 today.

This afternoon one of those tornadoes swept through Moore, Oklahoma, a southern suburb of Oklahoma City. This was a massive, devastating tornado. I watched it on radar and on a live television feed out of Oklahoma City. It was scary to see even though I was hundreds of miles away.  The tornado was at least a mile wide and was on the ground for about 20 miles (all of these numbers are preliminary until a survey can be completed). However, the most stunning realization that came to mind is that this is Moore's second encounter with a catastrophic tornado. On May 3, 1999 a massive tornado, rated F5 with winds in excess of 300 mph, struck Moore, killing 44 people, causing 581 injuries, and $1 billion in damages. Since May 1999 the residents of  Moore have had other encounters with tornadoes, but none the magnitude of today's tornado.

Tracks of the May 3, 1999 and May 20, 2013 Moore tornadoes.
Compiled by the National Weather Service Oklahoma City.

Here is a video of today's tornado as it moved through Moore.

As I write this there are already 51 confirmed fatalities from today's tornado. Rescuers continue to search for survivors in one of three schools that were hit by the tornado. Whole neighborhoods are unrecognizable.  The National Weather Service has preliminarily rated this tornado as an EF-4, but numbers don't convey the anguish of the families of those who lost their lives or the devastation to property that this community has experienced. There are a number of active CoCoRaHS observers in Moore and we hope they and their families are safe.

This tornado was well-warned. The tornado was on the ground for about 40 minutes, and a tornado warning was issued 16 minutes before the tornado developed.  I was astounded to hear people being interviewed state that they didn't know a tornado was approaching. It drives home the fact that no matter how soon warnings are issued, all of us have some personal responsibility to make sure we are aware of what is going on. Do you have a weather radio?  Every home and business should have one! There are smart phone apps that will alert you to severe weather wherever you are. The pendulum may be swinging back on this severe weather season. Make sure you are prepared.

April Recap - Cold, Snowy, Wet, and Dry

The weather during April 2013 was, in so many words, all over the place. Record cold and snow dominated the north-central U.S. Record rainfall and colder than normal weather plagued the central U.S., delaying spring planting and causing major flooding. Dry weather in the southwestern U.S got drier and drought conditions worsened there. April was also drier than normal in the northeastern U.S.

Here are some April statistics from the National Climatic Data Center. Some of these are preliminary and may change as new data arrives and is tabulated.

• North Dakota had its coldest April on record, 9.9°F below average.
• South Dakota, Nebraska, Kansas, Oklahoma, Minnesota, and Wisconsin each had a top ten cold April.
• It was the 7th coldest April on record for Alaska.
• Approximately 3,430 record low temperatures and about 4,050 record cold daily high temperatures were tied or broken. In comparison, approximately 690 record warm daily high temperature records and 1,570 record warm daily low temperatures were tied or broken. (These numbers are preliminary and are expected to change as more data arrive.)
• Duluth, MN had its snowiest month on record with 50.8 inches of snow, breaking the old record of 50.1 set in November1991. The previous record for the snowiest April was 30.6 inches in 1950.
• The April snow cover extent in the U.S. was the 5th largest on record.
• The April average precipitation for the contiguous U.S. tied with 1953 as the 19th wettest April on record.
• Iowa and Michigan both had their wettest April on record.
• Tennessee, Illinois, Indiana, and Wisconsin each had one of the ten wettest Aprils on record.
• While drought conditions improved in the central U.S., they worsened in the southwestern U.S. California experienced its driest January-April on record with only 27% of average precipitation. Snowpack in the Sierra Nevada was only 18% of normal.

Here is how the states ranked for temperature and precipitation.

You can read more about the April weather on the National Climatic Data Center's State of the Climate National Overview page, including narratives of regional highlights provided by the Regional Climate Centers.

Lumbering Low Lingers

The major upper level trough that brought snow to the Rockies, Midwest and as far south as Arkansas the first two days of the month is still producing rainfall in the eastern U.S. a week later.

The trough developed a closed circulation on May 3 and the closed low has been slowly, very slowly, making its way east through the southern half of the country.

Animation of the 7:00 a.m. CDT 500 millibar map for May 2-7, 2013

This morning the upper low was centered over northern Virginia and was responsible for more than two inches of rain in the mid-Atlantic region in the past 24 hours.

The path of this system can be seen in both the precipitation and temperature patterns for the past 7 days.  Precipitation from the Plains through the southeastern U.S. has been much above above normal as you might expect. The persistent cloudy, rainy, and cool weather has significantly delayed spring planting.

Total 7-day precipitation ending the morning of May 8, 2013.
Map from the NWS Advanced Hydrologic Prediction Service.

The low's progress across the country can also be discerned from the temperature departures over the last week.  Temperatures were much below normal along the storm's path. The ridge of high pressure over the northeastern U.S. kept temperatures much above normal from the Great Lakes through New England. Temperatures were also warmer than average along the west coast and in the Pacific Northwest where a high pressure ridge was also situated.

The closed low will continue moving northeast the next two days, and will finally dissipate as it moves off of the New England coast on Friday.

Heavy Snow, Heavy Rain, and Wildfire

It was another eventful weather day across the country, and not in the way you would normally picture the second day of May. The storm that brought snow to an area from the Rockies to northwestern Wisconsin continued to crawl eastward today, leaving a lot of records in its wake. A trough along the central Gulf brought 5 to more than 10 inches of rain to southwestern Alabama and southeastern Mississippi. Dry, warm, and windy weather prompted red flag warnings for southern California and other portions of the southwest U.S.

As of this morning a surprising 10 to 15 inches of snow was on the ground from southeastern Minnesota through northwestern Wisconsin, and accumulating snow continued in Wisconsin during the day.

Map prepared by the NWS Duluth office

As you might imagine, May snowfall records toppled with this storm. The NWS Cooperative Observer in Dodge Center MN (Dodge County) reported 15.4 inches of snow in the 24-hour period ending at 7:00 a.m. CDT this morning. If verified, this would be a new daily snowfall state record for May in Minnesota breaking the old record of 12 inches set on three previous dates, the most recent on May 3, 1954 near Leonard, MN.  Daily snowfall records were set at many locations in the storm-affected area in Iowa, Minnesota, and Wisconsin.

You can read more about the record snow in Minnesota and Wisconsin at the following NWS office web pages:

National Weather Service, Duluth MN
National Weather Service, LaCrosse, WI

In Omaha, NE the snow on May 1 and May 2 set daily records on both dates.  The combined total of 3.1 inches for May 1-2, 2013, is a record snowfall event in May as well as a record highest monthly snowfall total ever recorded in May.  In Lincoln, NE May 1 snowfall was 2.4 inches on May 1 and 0.2 for today (May 2), both daily records.  Kansas City, MO set new daily snowfall records on both May 1 and May 2.  The combined total of 3.1 inches for May 1-2, 2013, is a record snowfall event in May as well as a record highest monthly snowfall total ever recorded in May. 

This storm was clearly evident in the temperature pattern across the U.S. today, reflecting the strong upper level trough.

500 millibar (about 20,000 ft) upper level map for 7:00 p.m. CDT May 2

Surface temperatures at 7:00 p/m/ CDT May 2

The upper level ridge over the western U.S. was providing sunny and very dry weather. In California these conditions along with the Santa Anna winds combined to produce critical fire wildfire conditions in southern California, southern Nevada, and central Arizona. Red flag warnings were in effect for most of these areas today.

Fire weather outlook for May 2 issued by the NWS Storm Prediction Center

A wildfire in the Los Angeles area that initially was confined to about 10 acres this afternoon grew rapidly to 6,500 acres by late afternoon and as of this post is about 8,000 acres. A second wildfire was burning east of Los Angeles in Riverside County.

A slow-moving low pressure system along the central Gulf coast was brought up to a foot of rain to extreme southwest Alabama near Mobile and southeastern Louisiana.

CoCoRaHS rainfall map for May 2

Thunderstorms continued today, and more heavy rain is possible overnight.