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Torrential rains in Oklahoma; Summer in March continues for Midwest

By: Dr. Jeff Masters, 2:07 PM GMT on March 20, 2012

A significant flood event is underway in Eastern Oklahoma, where widespread rainfall amounts of 3 to 5 inches have fallen since yesterday. Up to four more inches of rain is likely today, and the National Weather Service in Tulsa is warning of the potential for "widespread and potentially catastrophic areal flooding and river flooding" should some of the higher rainfall amounts being forecast materialize. Numerous main-stem rivers across eastern Oklahoma and northwest Arkansas are now approaching flood stage, and will likely experience moderate to major flooding into Wednesday. Rainfall has also been heavy over Eastern Texas, with widespread amounts of 2 - 4 inches. These heavy rains are causing some street flooding, but in general, will be a benefit, as moderate to severe drought conditions still cover most of the region.


Figure 1. Radar-estimated rainfall for Eastern Oklahoma since March 19, 2012, as estimated by the Tulsa, Oklahoma radar.

The storm system responsible is a massive, slow-moving trough of low pressure over the Western U.S. that is colliding with the warmest and moistest air mass ever recorded in March in the Central and Eastern U.S. According to the NWS in Minneapolis, Minnesota, moisture flowing northwards into Minnesota along the cold front early this week had the highest levels of moisture ever recorded so early in the year. At the boundary between the Western U.S. trough of low pressure and Central U.S. ridge of high pressure, a cold front is lifting huge quantities of moisture-laden air aloft, forcing torrential rains to fall. The cold front is also expected to trigger a Slight Risk of severe weather over East Texas, Western Louisiana, and Southern Arkansas today, says NOAA's Storm Prediction Center. Severe thunderstorm watches are already posted for much of East Texas, as seen on our Severe Weather Map. Three tornadoes were reported yesterday in Texas, and eleven touched down the previous day in Oklahoma, Nebraska, and South Dakota. The tornado that hit North Platte, Nebraska two days ago was rated a strong EF-3, and injured four people.


Figure 2. Predicted rainfall amounts for the 2-day period Tuesday morning through Thursday morning show an area of 3+ inches (orange colors) is expected over Eastern Oklahoma, Arkansas, Louisiana, and Southwest Missouri. Image credit: NOAA HPC.

Summer in March continues for the Midwest
The ongoing March heat wave in the Midwest will continue to set all-time heat records through Thursday, gradually shifting its peak intensity eastwards during the week. A few highlights from yesterday's records:

Pellston, Michigan in the Northern Lower Peninsula is called "Michigan's Icebox", since it frequently records the coldest temperatures in the state, and in the entire nation. But the past three days, Pellston has topped out at 80° - 82°F, the first 80°F March days in their history. Yesterday's 82° reading broke the previous record for the date (56° in 1976) by an amazing 26°, and was 44°F above average. Nearby Traverse City hit 83°F yesterday, the third consecutive day the city has experienced its hottest March temperature on record.

International Falls, Minnesota hit 78°F yesterday, 42° above average, and the 2nd hottest March temperature on record in the Nation's Icebox. The record of 79°F was set the previous day. Remarkably, the low temperature for International Falls bottomed out at 60°F yesterday, tying the previous record high for the date. I've never seen a station with a century-long data record have its low temperature for the date match the previous record high for the date. Yesterday was the seventh consecutive day that International Falls broke or tied a daily record. That is spectacularly hard to do for a station with a century-long weather record. The longest string of consecutive records being broken I'm aware of is nine days in a row, set June 2 - 10, 1911 in Tulsa, Oklahoma (with weather records going back to 1905.) International Falls has a good chance of surpassing nine consecutive records this week.

Record heat in Canada
Record-breaking heat has also penetrated into the Prairie provinces of Canada over the past week. Winnipeg, Manitoba has broken its record high for the past five days in a row, and hit 24°C (75.2°F) yesterday, its hottest March temperature on record. Forecast high temperatures for Wednesday and Thursday across Ontario are near 26°C, which will threaten the records for hottest March day in history for Windsor, London, Hamilton, and Toronto.


Figure 3. The jet stream pattern features a large, southwards dipping bulge over the Western U.S., creating a trough of low pressure with cold and snow, and a large, northwards looping bulge over the Central U.S., creating a record-strength ridge of high pressure.

Why the record early-season warmth?
The unusual warmth is due to a loop in the jet stream that has created a large upper-level ridge of high pressure that is stuck in place over the Eastern U.S.--a phenomenon known as a "blocking pattern." Since the jet stream acts as the boundary between cold air to the north and warm air to the south, and the large loop in the jet places its axis far to the north of the eastern U.S., summer-like warmth has developed over the eastern half of the U.S. Conversely, colder than average temperatures have developed over the western third of the U.S. behind the southwards-dipping loop of the jet stream. This jet stream pattern is too extreme to be stable, and the big loop over the Western U.S. will break off and form a giant eddy on Wednesday. The resulting area of low pressure will be known as a "cut-off low", because it will be cut off from the jet stream. The cut-off low will drift slowly eastwards during the week, gradually bringing an end to "Summer in March" over the Eastern half of the U.S.

Jeff Masters
Lake Fog After T-storm
Lake Fog After T-storm
Spring Suprise
Spring Suprise
First and last snow of winter !

Heat Flood

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Pollen count almost hit 10,000 yesterday, has gone down today. Now we wait the the onslaught of pollen from pine trees (aka every other tree you see, or more)

The 80s are coming to and end:

Good morning all
Quoting StormTracker2K:
Over a FOOT of rain in western LA. If you remember some of these areas got 15" last week!


My word!
Quoting AussieStorm:
Congratulations St Mary%u2019s Primary School in Rydalmere, NSW, Australia(My kids school). The Weather Channel will be visiting your school on March 22.

On March 22 (the day before World Meteorological Day), The Weather Channel and Dick Whitaker will visit my kids school to:
- Assist your class in making the entered weather project
- Conduct a mini weather presentation
- Release a weather balloon from your school grounds (whole school can get involved).

How cool is that.


pretty cool...i just wish the NWS was doing it instead of twc. I sure woldnt be excited if TWC came to my house(IMO, of course)
Quoting StormTracker2K:



The heavy rain is now at the Louisiana/Mississippi border
Quoting SPLbeater:


pretty cool...i just wish the NWS was doing it instead of twc. I sure woldnt be excited if TWC came to my house(IMO, of course)

Dick Whitaker used to work for the BOM before TWC Australia started.
Quoting GeorgiaStormz:
Pollen count almost hit 10,000 yesterday, has gone down today. Now we wait the the onslaught of pollen from pine trees (aka every other tree you see, or more)

The 80s are coming to and end:

for just a short time they will rteturn warmer than before
Morning everyone! Wow the flooding in Louisiana is getting insane.
Quoting TampaSpin:
Morning everyone! Wow the flooding in Louisiana is getting insane.
its moving on now rains end from the west to east
Quoting KEEPEROFTHEGATE:
its moving on now rains end from the west to east
..


Ya i see that...WOW it was nearly stationary for 24hours raining over the same areas Continously....Glad its moving no matter how slow.



Looks like the SubTropical Jet is going to keep the South WET! WOW....then another DIP might be coming with another LOW at the end of the LOOP!
Quoting StormTracker2K:



Steaming
Quoting TampaSpin:
..


Ya i see that...WOW it was nearly stationary for 24hours raining over the same areas Continously....Glad its moving no matter how slow.
AGREED but needs to move at 20mph and get the heck outta there! its almost as if the storm is saying ahh... better I relax in this state for a while.
Sneak preview of CSU April forecast is up. The headline is less Active Atlantic in 2012.

Link
Quoting AussieStorm:
Congratulations St Marys Primary School in Rydalmere, NSW, Australia(My kids school). The Weather Channel will be visiting your school on March 22.

On March 22 (the day before World Meteorological Day), The Weather Channel and Dick Whitaker will visit my kids school to:
- Assist your class in making the entered weather project
- Conduct a mini weather presentation
- Release a weather balloon from your school grounds (whole school can get involved).

How cool is that.


That is awesome!! Do let us know how it goes.
Quoting Josihua2:
AGREED but needs to move at 20mph and get the heck outta there! its almost as if the storm is saying ahh... better I relax in this state for a while.


For sure a Drought Buster for some that needed.
Quoting nigel20:


Looks like LaNina is kicking into gear very well.
Those visit the Gulf Coast Commercials are working.
Quoting Josihua2:
AGREED but needs to move at 20mph and get the heck outta there! its almost as if the storm is saying ahh... better I relax in this state for a while.

Quoting TampaSpin:


For sure a Drought Buster for some that needed.
lol a piece of this storm need to branch off and pay a visit to Florida...
Quoting Tropicsweatherpr:
Sneak preview of CSU April forecast is up. The headline is less Active Atlantic in 2012.

Link

Thanks Tropicsweatherpr, so maybe 8-11 name storm, 4-6 hurricanes and 1-2 major hurricanes?
Quoting nigel20:

Thanks Tropicsweatherpr, so maybe 8-11 name storm, 4-6 hurricanes and 1-2 major hurricanes?
I predict 12 named storms 5 hurricanes 2 major......
Quoting TampaSpin:


Looks like LaNina is kicking into gear very well.

Yeah, La nina is stilll hanging on and will likely delay or inhibit the chance of an el nino...JMO
Quoting nigel20:

Thanks Tropicsweatherpr, so maybe 8-11 name storm, 4-6 hurricanes and 1-2 major hurricanes?


Looks like they will go with those.
Quoting Josihua2:
I predict 12 named storms 5 hurricanes 2 major......

What if we have a year similar to the 2011 pacific hurricane season...which had 11 name storms, 10 hurricanes and 6 major hurricanes
Quoting hydrus:
That is a huge amount of rain in a short amount of time. I would be surprised if they dont have significant damage in some areas. Thank you for noticing my 10,000th post. It really is a milestone for me..:)..This model forecast show the precipitation levels really well..Link




I'm not sure if those estimates are quite accurate, lets see if we actually have rain gauges to confirm. The radar already overestimated by as must as 10 inches in parts of Texas and Oklahoma. Some areas that got the most rain(4 to 6) the radar thought they had 12-15.


However it does seem the estimates are a bit better in Louisiana, but, still, lets get rain gauges to confirm, I wouldn't trust the radar. Sometimes radar underestimates dramatically as well. It frequently underestimates here. Last years total estimated rainfall by radar over my area showed about 40-45 inches. However, actual rain gauges in my area got anywhere from 50 to 70 for last year...



I know I already talked about this last night but not everyone noticed I guess :)



Anyways, I feel its always good to find rain gauges around the area and compare them with estimates. I haven't done a careful check on Louisiana as far as rain gauges in comparison to estimates, but, I did do a few comparisons and unfortunately that stripe of 10 inches in West Louisiana is probably fairly accurate.
Thunderstorms popping up everywhere to my east...:D
HPC Storm Summary

Excerpt:

...SELECTED STORM TOTAL RAINFALL IN INCHES FROM 700 PM CDT SUN MAR
18 THROUGH 900 AM CDT WED MAR 21...



...LOUISIANA...
NATCHITOCHES 0.9 NE 8.91
FORT POLK 7.12
DERIDDER 5.95
SIMSBORO 0.3 WNW 5.74
STARKS 5.50
PLAIN DEALING 3.3 ESE 5.40
HOMER 1.2 N 5.21
MINDEN 2.0 NE 5.08
SHREVEPORT 9.1 SE 5.01
MINDEN 2.2 NE 4.86
BOSSIER CITY 7.9 NNW 4.67
VINTON 4.30
SHREVEPORT 4.06

Guess they left out this gage:

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE SHREVEPORT LA
651 AM CDT WED MAR 21 2012

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0645 AM HEAVY RAIN 10 SSE PROVENCAL 31.52N 93.14W
03/21/2012 M10.19 INCH NATCHITOCHES LA PARK/FOREST SRVC

MEASURED 10.19 RAINFALL AT KISATCHIE RANGER STATION 24
HOUR-OBSERVATION ENDING AT 6 AM MARCH 21 2012.
Quoting Josihua2:
lol a piece of this storm need to branch off and pay a visit to Florida...



Unfortunately I don't see any sign of drought improvement coming for Florida. In fact we may suffer with increasing drought into May without hardly any relief.
Quoting Jedkins01:




I'm not sure if those estimates are quite accurate, lets see if we actually have rain gauges to confirm. The radar already overestimated by as must as 10 inches in parts of Texas and Oklahoma. Some areas that got the most rain(4 to 6) the radar thought they had 12-15.


However it does seem the estimates are a bit better in Louisiana, but, still, lets get rain gauges to confirm, I wouldn't trust the radar. Sometimes radar underestimates dramatically as well. It frequently underestimates here. Last years total estimated rainfall by radar over my area showed about 40-45 inches. However, actual rain gauges in my area got anywhere from 50 to 70 for last year...



I know I already talked about this last night but not everyone noticed I guess :)



Anyways, I feel its always good to find rain gauges around the area and compare them with estimates. I haven't done a careful check on Louisiana as far as rain gauges in comparison to estimates, but, I did do a few comparisons and unfortunately that stripe of 10 inches in West Louisiana is probably fairly accurate.
You have a good point Jed. Radar is not infallible and makes incorrect measurements at times. Rain gauges are the best way to measure rain if it is not to windy. I think eventually they will tweak the radar enough to get those more accurate rainfall amounts. I have witnessed the radars get it right too, so it does have the ability. In the transmitted radar signal, the electric field is perpendicular to the direction of propagation, and this direction of the electric field is the polarization of the wave. Radars use horizontal, vertical, linear and circular polarization to detect different types of reflections. For example, circular polarization is used to minimize the interference caused by rain. Linear polarization returns usually indicate metal surfaces. Random polarization returns usually indicate a fractal surface, such as rocks or soil, and are used by navigation radars. We have come a long way tho.This is Hurricane Abby approaching the coast of British Honduras. The complete eyewall cloud is visible. Location: Near British Honduras (Belize)
Date 15 July 1960
Source NOAA photo lib
Author NOAA's National Weather Service..Wiki
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536. MahFL
Drought through at least June in FL.