SIGNIFICANT SEVERE WEATHER EVENT EXPECTED FOR CHRISTMAS DAY OVER PARTS OF THE GULF COAST STATES..SYNOPSIS ISSUED DEC. 24, 2012…3:10 P.M. EST…PHFC

Merry Christmas everyone!

SIGNIFICANT SEVERE WEATHER EVENT EXPECTED FOR CHRISTMAS DAY OVER PARTS OF THE GULF COAST STATES

The main body of this synopsis will be regarding the current DAY 2 Convective Outlook in which a portion of the SLIGHT risk area has been upgraded to a MODERATE risk area.

The SPC has issued a SLIGHT risk of Severe Thunderstorms overnight for portions of CENTRAL-E TX AND WRN LA…

SPC DAY 1 CONVECTIVE OUTLOOK

The current developing storm system is forecast to strengthen tonight as it progresses eastward.  From the SPC message text:
TX/LA AREA OVERNIGHT…CONVECTIVE POTENTIAL WILL INCREASE OVERNIGHT…FIRST N OF SFC FRONT LATE EVENING THROUGH PRE-DAWN HOURS WITH MOST INTENSE CELLS POSING HAIL THREAT. ACTIVITY MAY DEVELOP PROGRESSIVELY CLOSER TO FRONT THROUGH END OF PERIOD…EVENTUALLY BECOMING SFC-BASED WITH SUPERCELLS AND BOW/LEWP FEATURES POSSIBLE. AS SUCH…THREAT EXISTS DURING LAST FEW HOURS OF PERIOD FOR SVR HAIL/GUSTS. TORNADO RISK EXISTS FROM ANY SFC-BASED AND RELATIVELY DISCRETE CELLS IN WHAT SHOULD BE VERY FAVORABLE SHEAR ENVIRONMENT…BUT COVERAGE OF SFC-BASED TSTMS IS TOO UNCERTAIN ATTM FOR MORE THAN 5% UNCONDITIONAL TORNADO RISK.  

DEEP SHEAR AND LOW-LEVEL HODOGRAPHS EACH ARE EXPECTED TO STRENGTHEN OVER RETURNING WARM SECTOR TONIGHT…AS 60S F SFC DEW POINTS CONTRIBUTE TO 1000-1500 J/KG MLCAPE BY 12Z ALONG AND S OF FRONT OVER SE TX. LARGEST LOW-LEVEL HODOGRAPHS WILL BE ALONG FRONT…WHERE BACKED SFC WINDS WILL CONTRIBUTE TO EFFECTIVE SRH 300-500 J/KG. SRH ALSO WILL BE FAVORABLE FARTHER S OVER COASTAL AREAS IN WARM SECTOR…HOWEVER FCST SOUNDINGS SUGGEST PRONOUNCED EML-BASE INVERSION BETWEEN 850-700 MB THAT MAY RESTRICT TSTM COVERAGE AWAY FROM BOUNDARIES. 

Put plainly, any tornado activity may be limited close to the frontal feature given the presence of a 850-700 mb inversion which should limit Tstm activity away from boundaries.

During my analysis, various parameters suggest to me, that there could be an increase of the  current 5% tornado probability as this system continues to strengthen later into the evening.  Analysis of SRH and 2 tornado parameter models indicate this may be a possibility, although the main threat based on soundings are damaging straight line Tstm winds and hail associated with any elevated supercell storms and bow echoes.

Residents should monitor local NWS statements, watches and warnings as issued, and tune to NOAA Weather Radio.  I will have interactive maps posted at the end of this discussion, so you may stay up to date on any significant severe weather for your area.

The SPC has issued an upgraded Day 2 Convective Outlook, to include a MODERATE risk area.

SPC DAY 2 CONVECTIVE OUTLOOK

Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe weather within 25 miles of a point. 

The aforementioned system is forecast to continue to strengthen.  Analysis of the 500 mb and 200 mb level maps today indicate a pretty potent jet at both levels, with the exit region situating itself over the SLIGHT risk area.  Albeit most of the forecast parameters which have not been updated since earlier today, do not correlate with the SPC text.  However, careful analysis of F5 Data severe weather forecast software, combined with the forecast parameters provided in the SPC outlook, indicate the potential for a significant severe weather event.  Based on Significant Tornado Parameters, Helicity, Moisture, Shear, and projected CAPE values of 1000-1250 J/KG near the coast, there will be sufficient energy and rotation within the atmosphere for some STRONG TORNADOES within the MODERATE risk area.  These could become long tracked in nature.  Again, since  some of the data posted has not exactly matched up, I believe to gather a better idea of the strength of severity, I will be reviewing soundings in the a.m. from around the risk area, which will yield better information as to the various forecast parameters.  I will be monitoring to see if this has the potential to become a PDS (Potentially Dangerous Situation) based on what the forecast parameters indicate tomorrow.  Should this occur, this office will issue a statement to that effect.  Sometimes these situations will prompt SPC to issue a Tornado Watch tagged with a statement PDS if conditions warrant.  If your area SHOULD come under one of thee POSSIBLE watches, PLEASE…pay particular attention to your surroundings and be prepared to take IMMEDIATE action if a Tornado Warning is issued.  Also based on some parameters, I am not ruling out the possible extension northward to the borders of MS/AL of a possible tornado threat…Soundings in the a.m. will determine this.

There is another SLIGHT risk issued in the Day 3 Outlook, and will be included in tomorrow’s synopsis

I will have an update tomorrow.

SPC CONVECTIVE WATCH DISPLAY

SPC MESOSCALE DISCUSSIONS DISPLAY

NWS ACTIVE WATCH, WARNING, AND HAZARDS MAP (CLICK ON YOUR STATE)

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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12 Responses to SIGNIFICANT SEVERE WEATHER EVENT EXPECTED FOR CHRISTMAS DAY OVER PARTS OF THE GULF COAST STATES..SYNOPSIS ISSUED DEC. 24, 2012…3:10 P.M. EST…PHFC

  1. teammc01 says:

    Merry Christmas, StormW

  2. originallt says:

    Thanks Storm for your continued work. Just on a happier note up here in Stamford CT. we have our “White Christmas”!. It’s snowing now, about 32.5F Baro. 29.98F and we have 1″ on the ground It should stop however, before 11PM. That precipitation shield is really moving fast from SW to NE and should clear our area by about that 11PM time. Very pretty out side now. Merry Christmas again to Storm, his family, and My “blog” family here at Storm’s place!

    • Monty says:

      Yeah LT…we’re with you…we are expecting 4 to 8 inches above 7000 FT…3 to 5 inches in Denver and well over a foot in the Ski Resorts (Breckenridge/Vail/Copper Mtn)…temps with the arrival of the Arctic Airmass…5 above zero to 20F…Baro at 29.88 at 7766 ft.

  3. DKMac says:

    Thanks Storm! Looks like I may be BBQing my Christmas roast wearing my slicker suit here in Covington, LA and listening to the weather radio.

    Merry Christmas Storm, and to all. I hope that all of us down here in the Gulf Coast area don’t have any problems tomorrow.

  4. Thanks Storm. I told the gang I would pass your synopsis on to them when I got it. You’re awesome Senior Chief…always on top of it!! Everyone have a Very Merry Christmas!!

  5. jdpjustice says:

    Hi storm. Thanks for the update. I’m in Lake Charles. It looks like its going to be a ” rocky” Christmas Day! Thanks and merry Christmas!!

  6. stefanie says:

    Thanks Storm. So beautiful now, hard to believe this mess will be cranking up in a few hours. Hope you and yours and everyone has a happy and safe Christmas.

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