SEVERE WEATHER FORECAST SYNOPSIS…ENHANCED RISK ADDED…ISSUED FEB. 07, 2017…10:20 A.M. EST

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(T. F. “Storm” Walsh III)

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Good day everyone!

As of the 1300Z update from the Storm Prediction Center (SPC), a small ENHANCED risk are for Severe Thunderstorms has been designated ACROSS PORTIONS OF LA/MS/AL TO FL PANHANDLE…

A SLIGHT risk is in effect ACROSS THE GULF COAST STATES/LOWER MS RIVER VALLEY AND TN VALLEY…

A MARGINAL risk covers THE CENTRAL GULF COAST TO THE OHIO VALLEY AND MIDWEST…

SPC DAY 1 CONVECTIVE OUTLOOK
day1otlk_1300

day1probotlk_1300_torn

day1probotlk_1300_hailProbability of one inch diameter hail or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of two inch diameter hail or larger within 25 miles of a point. 

day1probotlk_1300_wind

From the SPC:

…SUMMARY…
Severe thunderstorms are expected today especially across the lower Mississippi Valley and central Gulf Coast states, but some strong to severe thunderstorms may occur as far north as the Tennessee Valley and Ohio Valley.

…Portions of LA/MS/AL to FL Panhandle… A southern-stream shortwave trough (and related mid/high-level speed max) will continue to amplify and spread generally east-southeastward today toward the central Gulf Coast States. Strengthening low/mid-level southwesterly winds will support the continued northeastward transport of low/middle 60s F surface dewpoints across additional portions of MS/AL.

Showers/thunderstorms are already increasing within the modestly moist early-day warm sector across southern/eastern LA into MS. Many of these storms should become increasingly surface based into late morning/early afternoon as additional moistening and destabilization occurs. 12Z observed soundings from Shreveport (SHV) and Lake Charles (LCH) sample severe-favorable thermodynamic profiles with very steep mid-level lapse near or excess of 8.0 C/km, aside from 35-45 kt of effective shear.

Steadily increasing deep-tropospheric winds and lengthening hodographs, in conjunction with cool mid-level temperatures (roughly -14C to -17C at 500 mb) and steepening lapse rates, appears likely to support supercells capable of large hail, along with some tornado/damaging wind risk, especially from mid/late morning into the afternoon. Storms may merge over time and grow upscale with at least a modestly increased damaging wind risk into AL and the FL Panhandle this afternoon, although the eastward progression of the presumed convective line may eventually outrun the greater low-level moistening/destabilization.

For additional details on the expected early-day evolution of storms, please reference Mesoscale Discussion 144.

…Tennessee Valley/Ohio Valley/Midwest…
Ahead of a cold front, moist advection will continue to occur in concert with 50+ knot low-level southwesterly winds. Mostly linear bands of strong to locally severe convection are ongoing early this morning from east-central AR into western TN. These storms should develop eastward across additional portions of TN and northern portions of MS/AL. While these storms are likely to develop east of the primary moist/instability axis, a modestly increasing potential for damaging winds, some hail and brief tornado risk can be expected during the day eastward into at least middle TN and northern portions of MS/AL.

Farther north into the Ohio Valley and Midwest, current thinking is that extensive ongoing precipitation south of the Ohio River and related cloud cover will tend to hinder appreciable destabilization. While weak buoyancy/strong vertical shear could support some stronger/potentially severe low-topped storms, the overall severe risk should remain limited.

Analysis of F5 DATA forecast soundings from the RAP model this morning, tends to suggest that the strongest severe weather, and tornado threat may hang back slightly further west.  In fact, upon analysis of indexes and indices, of both the RAP and SPC SREF model, I am not sure as to why the slight risk was extended so far north, but I am sure there is good reason SPC has done this.

Based on forecast soundings of EHI, STP, SWEAT INDEX, and LIFTED INDICES, the RAP model 12Z run tends to suggest the following outlined areas may be where the best chance for supercell development to occur.  The first outline covers from current, to 2:00 p.m. EST.  The second outline from after 2:00 p.m. through 5:00 p.m. EST.  These supercells, especially stronger cells displaying rotation, will have the capability of producing large damaging hail, damaging straight line thunderstorm winds, and tornadoes.

RAP SUPERCELL BEST PROBABILITY
f5data-rap-supercell-1

f5data-rap-supercell-2

The following outlined areas are suggested as to where the best probability of isolated tornadoes may occur.  Based on various parameters, some isolated tornadoes could possibly be strong and long lived (long track), mainly over the areas of MS/AL, with the slight probability of some tornado activity lingering over the extreme west portion of LA. 
The first outline covers from current, to 2:00 p.m. EST.  The second outline from after 2:00 p.m. through 5:00 p.m. EST.

RAP BEST TORNADO PROBABILITY
f5data-rap

f5data-rap-2

At the time of issuing this synopsis, a TORNADO WATCH was in effect, and a TORNADO WARNING had already been issued earlier this morning for a portion of LA:

EARLIER TORNADO WARNING:
http://forecast.weather.gov/wwamap/wwatxtget.php?cwa=usa&wwa=Tornado%20Warning

CURRENT TORNADO WATCH (LINKED TO WATCH TEXT)
ww0026_overview_wou

Residents within the ENHANCED and SLIGHT risk areas should monitor NOAA Weather Radio, local news outlets, and local NWS statements regarding today’s severe weather threat.

IF A TORNADO WARNING IS ISSUED FOR YOUR AREA…SEEK SHELTER IMMEDIATELY.

TORNADO SAFETY RULES WITH INSTRUCTION ON HOW TO TAKE COVER
http://www.spc.noaa.gov/faq/tornado/safety.html

The following graphics are linked, as the graphics will not automatically update on this site.  PLEASE check them often by clicking on them for up to date information on watches and warnings.  Warnings will be posted on the NWS Hazards and warnings map.

SPC CONVECTIVE WATCHES DISPLAY

SPC MESOSCALE DISCUSSIONS DISPLAY

NWS HAZARDS AND WARNINGS DISPLAY

INTELLICAST NWS DOPPLER RADAR ANIMATION


ridge_sitemap

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
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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10 Responses to SEVERE WEATHER FORECAST SYNOPSIS…ENHANCED RISK ADDED…ISSUED FEB. 07, 2017…10:20 A.M. EST

  1. originallt says:

    I got 11″ of snow from the storm we had up here, in Stamford CT. It ranged from about 10-18″ in the whole state of CT. –NYC got 9.4″. So in general it was a pretty good North East snow storm. Winds were gusting 30-40mph. at times. Near Blizzard Conditions. Temps. were in the 20’s, and fell to 8F by Friday morning. Baro’s. lowest point here was 29.49″. Now all the way up to 30.20″ at 10:40 AM Friday!

    • I once spent some 6 months near Easton, CN, not too far from Stamford. That was 1947 when I attended Bassick Sr. HS in Bridgeport. It was winter and we hardly had snow that year, the max was 4″ !! One weekend we drove into Stanford to see a movie and we got stuck there for a couple of hours! Not by snow, but when we exited the movie we were caught up in a filming of the opening scene of the movie “Boomerang” starring Dana Andrews. At age 16 I enjoyed the delay in getting home. I have enjoyed the movie several times since then! Beautiful place. Hope it never deteriorates!

  2. originallt says:

    Glad you , dellamom are, OK and didn’t lose your house. Prayers out to all the rest of the people down there. Looks like some of that energy will translate Northeastwards into my area by Thursday, along with a shot of cold air. We, those of us in CT. and the greater NYC area, and of course and especially Eastern New England, could get over 1 foot of SNOW!!

    • dellamom says:

      I hope you have a good snow blower. I spent one year in Minnesota, and it was a very mild winter. I loved the ice skating, but the shoveling … not so much.

  3. Mac says:

    The tornado passed about 7 miles south of us. Madisonville, LA was hit pretty hard along with New Orleans East. Thanks for the heads-up Storm!

    • dellamom says:

      Mac, my office is in Madisonville on Hwy 21 next to Lake Castle. We were spared, but it hit close enough for me. My house just south of Abita is safe, too. At lunch, one of us got a text alert that more is on the way for this afternoon. That tracks with Storm’s report of the second circle after 2:00. Waiting to see what happens. My husband was on his way to Chalmette (against my request) across the twin spans crossing Lake Pontchartrain on the eastern side when the large tornado hit New Orleans East. He saw the tornado and said there were fire and police personnel on the bridge taking photos of the tornado from that vantage point. Prayers to all who were stricken. Prayers to those in the path of anything coming along behind it. Thank you from the bottom of my heart, Storm. I knew about it before the phone alerts started blowing up.

  4. Monty says:

    Eeeek Dellamom!! Stay safe over there. We’re going to miss this one. That’s ok…city still cleaning up after Super Blow LI. Darn Falcons.

  5. dellamom says:

    Mac, we are in the bullseye today. Keep safe, neighbor. Thank you, Storm for the many services you provide to us.

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