URGENT SEVERE WEATHER FORECAST SYNOPSIS…WIDEST DISSEMINATION REQUESTED…WIDESPREAD SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER MISSISSIPPI TO OHIO VALLEYS THIS AFTERNOON AND TONIGHT…DEC. 21, 2013…ISSUED 12:40 P.M. EST…PHFC

DONATIONS NEEDED
Funny dog holds dollars in mouth, isolated white background

Good afternoon everyone…looks like a rough day ahead for some in the south.  The Storm Prediction Center, Norman, OK. has issued a Public Severe Weather Outlook…issued at 2:37 a.m. CDT. The SPC has also extended and broadened the MODERATE risk area this morning in the Day 1 Convective Outlook.

SPC DAY 1 CONVECTIVE OUTLOOK

SPC TORNADO PROBABILITY MAP

SPC PUBLIC SEVERE WEATHER OUTLOOK STATEMENT
http://www.spc.noaa.gov/products/outlook/pwo.html

Analysis of current upper level and surface maps indicates shear will be sufficient enough to allow for rotating supercell thunderstorms.  A moderate LLJ is in place, with a strong SWLY flow from the 500 mb level, up to 200 mb, where a Jetstreak on the order of over 100+ knots is over the region.  This setup will continue to shift North and East throughout the day.

Analysis of Severe Weather Indices and Parameters from output of the GFS, NAM-WRF models through F5 Data Severe Weather Software indicates tornado activity through this afternoon, will most likely occur within the 10% prob. range shown in the SPC map.  I was going to provide my own graphic for this next portion, however SPC has accomplished this for me.   Based on the same F5 Data analysis, tornadoes within the hatched region may most likely attain EF2 – EF3 status.

Albeit CAPE is not really dramatic, some of the morning soundings do forecast SBCAPE could attain 1000 – 1400 j/kg in some portions of the moderate risk area.  Other parameters however are fairly positive for some isolated strong tornadoes, especially if cloud cover dissipates.  Dew-points over the area will remain within the 60F – 70F range through tonight.  Lifted Indices are forecast to range between -2 to -6.  The SWEAT Index values from now until around after 3:00 p.m. EST are forecast to average around 400 – 425.  400+ in this value indicates tornadic supercells are pretty much likely.  SRH (Storm Relative Helicity) is forecast to range around 300-600 in some isolated areas within the hatched area.

Given the forecast of a very moist setup up to the 500 mb level, and decent helicity, a threat for some isolated tornadoes cannot be ruled out later this evening into the overnight hours in the Ohio Valley region.

Residents who own one, are urged to monitor NOAA Weather Radio, and tune in to local news stations for breaking news on severe weather.  Residents should also monitor local NWS office statements and warnings if issued.  ALL maps and graphics here are linked in order for you to keep current with Watches Warnings and Statements.  The NWS Hazard and Warnings display is linked as such, that you click on your state for current watch, warning, and statement information.  I  will be in and out of the office today checking the progress of this situation, and will try to update accordingly.

SPC CONVECTIVE WATCHES DISPLAY

SPC MESOSCALE DISCUSSIONS DISPLAY


NWS WARNINGS AND HAZARDS DISPLAY (CLICK ON YOUR STATE)

NWS DOPPLER RADAR

Have a blessed day!

T. F. “STORM” WALSH III 
GMCS, USCG (ret) 
METEOROLOGIST / HURRICANE SPECIALIST 
MEMBER WEST CENTRAL FL AMS  
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced) 
CoCoRaHS OBSERVER

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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2 Responses to URGENT SEVERE WEATHER FORECAST SYNOPSIS…WIDEST DISSEMINATION REQUESTED…WIDESPREAD SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER MISSISSIPPI TO OHIO VALLEYS THIS AFTERNOON AND TONIGHT…DEC. 21, 2013…ISSUED 12:40 P.M. EST…PHFC

  1. Monty says:

    Thanks Storm…looks like IAH and SHV under the gun for my gang for now…will pass this on to all of them in the SEUS as this looks to spread East throughout the day. Thanks always for your dedication Storm!!

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