ENHANCED SEVERE WEATHER THREAT FORECAST SYNOPSIS…ISSUED MAR. 01, 2017…12:10 P.M. EST

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(T. F. “Storm” Walsh III)

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Good day everyone!

The following PWO was issued by SPC earlier this morning:

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0806 AM CST WED MAR 01 2017
…Severe thunderstorms expected over parts of the northern Tennessee, southern Kentucky, and far western Virginia area this morning…

* LOCATIONS…
Southern Kentucky Northern Tennessee Far western Virginia

* HAZARDS…
Widespread damaging winds A couple of tornadoes Isolated large hail

* SUMMARY…
Widespread wind damage is forecast across parts of Kentucky and Tennessee this morning. Severe thunderstorms will continue to spread across the Ohio and Tennessee Valley regions into the Middle Atlantic states, possibly into southern New England by mid afternoon. Damaging winds are the primary severe threat, though a few tornadoes and hail will be possible, especially west of the Appalachians.

Preparedness actions…
Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A watch means that conditions are favorable for severe thunderstorms over the next several hours. If a severe thunderstorm warning is issued for your area, move to a place of safety, ideally in an interior room on the lowest floor of a sturdy building.

The Storm Prediction Center (SPC) has designated the following risk area regarding the Day 1 Convective Outlook:

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NORTHEAST MS…NORTHERN AL…AND SOUTHERN TN NORTHEASTWARD TO THE MID-ATLANTIC…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED FROM PARTS OF THE LOWER MS VALLEY TO SOUTHERN NEW ENGLAND…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT ACROSS PORTIONS OF THE EASTERN STATES…

SPC DAY 1 CONVECTIVE OUTLOOK MAPS
day1otlk_1630

SPC TORNADO PROBABILITY
day1probotlk_1630_torn

SPC HAIL PROBABILITY
day1probotlk_1630_hail

SPC DAMAGING WIND PROBABILITY
day1probotlk_1630_wind

SPC THUNDERSTORM PROBABILITY TIMING MAPS (VALID TIMES LOCATED BOTTOM LEFT IN GRAPHIC)
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STORM PREDICTION CENTER LINK
(http://www.spc.noaa.gov/)

SPC SUMMARY
Severe thunderstorms with damaging winds are expected from portions of the Southeast to the Mid Atlantic region and parts of southern New England. Damaging winds will be likely, and the risk for tornadoes will exist particularly from parts of northeast Mississippi to portions of north Georgia and vicinity.

…Portions of the Southeast to the Mid-Atlantic region and southern New England…
An extensive belt of strong mid/high-level flow across the Southern and Eastern States will maintain strong deep shear over a moist and diurnally destabilizing warm sector across the area. A squall line from Middle TN toward the central Appalachians will likely spread across the adjacent Piedmont during the next several hours. Re-intensification of this activity is expected, owing to the presence of adequate moisture return (upper 50s to lower 60s dewpoints) amidst surface heating and relatively steep midlevel lapse rates. Swaths of damaging wind gusts will be likely as this activity spreads toward the coastal plain through the evening. A couple of tornadoes will be possible. Severe-wind probabilities have been increased eastward across the Piedmont area.

More separated updrafts/discrete convection are evolving across parts of the lower MS Valley, at the southern end of a zone of stronger deep ascent. As this activity spreads eastward toward parts of the southern Appalachians and vicinity, it will intercept a relatively more moist boundary layer supporting stronger instability further aided by steep midlevel lapse rates (around 8.5 C/km in the 700-500-mb layer per the 12Z Jackson sounding). With 250-350 m2/s2 of effective SRH associated with modestly curved though long hodographs, tornado probabilities have been increased in this area.

JAN SOUNDING PAGE (HODOGRAPH UPPER RIGHT CORNER)
jan

With northward extent across the East (i.e., toward southern New England and vicinity), weaker instability will exist owing to more widespread cloud coverage amidst an antecedent cooler/drier boundary layer. However, strong vertical shear profiles will support a conditional severe risk.

Modest destabilization may take place around the upper Ohio Valley and eastern Great Lakes area amidst recycled moisture ahead of the primary cold front, perhaps supporting a band of strongly forced convection spreading eastward from the late afternoon through the evening. Locally damaging wind gusts may accompany this activity.

At the time of my analysis, severe weather was ongoing, with a notable squall line making its way east at a pretty good clip.  Based on the above information from SPC, and analysis of F5 DATA forecast soundings from both the RAP and NAM-WRF models, I had to incorporate both models, given the variance of the model run times, in order to make a time line.  Modeling suggests the outlined areas have the highest probability from 12:00 NOON to late afternoon, for the occurrence of the strongest storms and probable tornadic cells, mainly embedded within the squall line.  Based on running out the soundings to early evening, the severe weather is forecast to continue to move eastward, but should begin to lessen in severity after 3:00 – 4:00 p.m. CST.

NAM 12:00 P.M. CST
f5data-nam-12pmcst

RAP 2:00 P.M. CST
f5data-rap2pmcst

NAM 3:00 P.M. CST
f5data-nam-3pmcst

f5data-nam-3pmcst-2

Modeling suggests that after 3:00 – 4:00 p.m. CST, an isolated area for severe weather may exist over west to central NC.

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. PLEASE, visit back often and click on the graphics for current, up to date information.

SPC CONVECTIVE WATCHES

SPC MESOSCALE DISCUSSIONS

NWS HAZARD AND WARNING DISPLAY

NWS DOPPLER RADAR SITE
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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2 Responses to ENHANCED SEVERE WEATHER THREAT FORECAST SYNOPSIS…ISSUED MAR. 01, 2017…12:10 P.M. EST

  1. dellamom says:

    Thank you, Storm. We are just inside the marginal area. Prayers to those North of us.

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