SEVERE WEATHER / PRELIMINARY SEVERE WEATHER FORECAST SYNOPSIS…ISSUED FEB. 27, 2017…11:40 A.M. EST

Disclaimer:  This site is not affiliated with the National Hurricane Center, Hurricane Hunters, Storm Prediction Center, or National Weather Service.  ALL forecasts herein are the result of my analysis, and I am solely responsible for the content.
(T. F. “Storm” Walsh III)

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Good day everyone!

The Storm Prediction Center (SPC) has designated the following risk area regarding the day 1 convective outlook:

SPC DAY 1 CONVECTIVE OUTLOOK MAPS

SPC TORNADO PROBABILITY

SPC HAIL PROBABILITY

SPC DAMAGING WIND PROBABILITY

SPC OUTLOOK TEXT / SUMMARY / SYNOPSIS:

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF NORTHEAST TX…SOUTHWEST AR…AND NORTHWEST LA…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE ARKLATEX REGION AND THE LOWER MS VALLEY…

…SUMMARY…
A few severe storms will be possible today over parts of Texas and northwest Louisiana. Other strong storms will affect portions of the Arklatex region and Lower Mississippi Valley.

…TX/LA…
Satellite imagery shows a shortwave trough axis extending from western KY southwestward into central TX. Lift ahead of this trough has resulted in a few showers and thunderstorms to develop over central TX. The air mass ahead of the storms is moist and moderately unstable, with afternoon MLCAPE values expected to range from 1000-2000 J/kg. Relatively steep mid level lapse rates and favorable deep-layer shear values suggest the risk of discrete supercells capable of large hail. A remnant surface boundary extends from northeast TX into central LA. Enhanced shear in vicinity of this boundary causes some concern for an isolated tornado or two later today if a storm moves into this zone.

…LA/MS…
Scattered thunderstorms will be possible farther east along the boundary into southern LA and southern MS. Weaker thermodynamic and wind parameters suggest only a marginal risk of severe storms in this area, but an isolated severe hail or wind report cannot be ruled out.

Based on my analysis of current forecast sounding data from F5 DATA software, using both GFS and NAM-WRF combined solutions, forecast indices and parameters at the moment, indicate the best probability for the strongest storms / supercells lies within the outlined areas, with the peak approximately occurring between 3:00 p.m. – 6:00 p.m. CST.

F5 DATA 3:00 – 6:00 P.M.CST  GFS SOLUTION
f5data-gfs-6pmcst

F5 DATA 3:00 – 6:00 P.M. CST NAM-WRF SOLUTION
f5data-nam-6pm-cst

Based on the same analysis, using various tornado parameters, I have extended the tornado probability area in the following maps:

F5 DATA NAM-WRF 3:00 P.M. CST
f5data-nam-3pmcsttor

F5 DATA NAM-WRF 6:00 P.M. CST
f5data-nam-6pm-csttor

Here are a few of the forecast sounding values that were displayed within the outlined areas:

LIFTED INDEX: -4 to -8
SBCAPE : 1000 – 2000 j/kg
MLCAPE: 1000 – 1500 j/kg
SHOWALTER INDEX: -4 to -2

Based on CAPE and LIFTED INDEX values, some hail could be significant.  SPC mentions Missouri for later tonight and overnight which is probable, albeit forecast soundings at the moment did not reveal this.  I concur with the SPC 2% and 5% tornado probability, and any tornado activity that may occur, should be associated with stronger squalls and/or stronger supercells.  Residents under the risk area, especially for TX and LA, should monitor NOAA Weather Radio, Local news outlets, and NWS Statements.

The following graphics are linked for you to receive up to date information on SPC Watches and Mesoscale Discussions.  The NWS Hazard and Warning Display is linked.  Click on the map, and then click on your area for up to date NWS Statements and Warnings.

SPC CONVECTIVE WATCHES
validww

SPC MESOSCALE DISCUSSIONS
validmd

NWS HAZARD AND WARNING DISPLAY
us

If you go to the top of my page, below the graphic with the NHC Logo, and Hurricane Hunter aircraft, click on Satellite and Radar page for the latest radar images.

The Storm Prediction Center (SPC) has designated the following risk areas regarding the probability for Severe Thunderstorms in the Day 2 Outlook for Tuesday:

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL AND NORTHERN ARKANSAS INTO SOUTHEASTERN MISSOURI AND ADJACENT PORTIONS OF SOUTHERN ILLINOIS…WESTERN KENTUCKY…AND WESTERN TENNESSEE…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX NORTHEASTWARD THROUGH THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND INTO THE OHIO VALLEY…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK…

SPC DAY 2 CONVECTIVE OUTLOOK (CLICK GRAPHIC FOR OUTLOOK TEXT)day2otlk_0700

day2probotlk_0700_any
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.

I did analyze some forecast sounding data regarding tomorrows severe weather, however based on SPC comment on the complexity and uncertainty of some severe parameters, forecast sounding data could modify…thus I will omit the data from this synopsis.  However, if current forecast sounding data holds, or if values increase, I would not be surprised to see a small MODERATE risk area show up within the significant probability, hatched area on the current probability map.  I should be able to perform an analysis tomorrow morning, and hopefully get something out by noon time, or shortly after.

The Storm Prediction Center (SPC) has designated the following risk areas regarding the probability for Severe Thunderstorms in the Day 3 Outlook for Wednesday:

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PARTS OF MISSISSIPPI…ALABAMA…AND NORTHWESTERN GEORGIA INTO MIDDLE AND EASTERN TENNESSEE AND CENTRAL AND SOUTHEASTERN KENTUCKY…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MISSISSIPPI VALLEY THROUGH PARTS OF THE SOUTHERN AND CENTRAL APPALACHIAN STATES AND INTO THE MID-ATLANTIC STATES…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL GULF COAST NORTHEASTWARD INTO PORTIONS OF THE NORTHEAST…

…SUMMARY…
Strong to severe thunderstorms will be possible from the lower Mississippi Valley northeastward across the Tennessee Valley and southern Appalachians, and northward into parts of the Mid-Atlantic states and perhaps portions of the Northeast.

SPC DAY 3 CONVECTIVE OUTLOOK (CLICK GRAPHIC FOR TEXT)
day3otlk_0830

day3prob_0830

I intend to have an update on the Wednesday outlook, however I will not be able to begin analysis until after 12:30 p.m., due to a doctor appointment and other commitments.

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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