013
ACUS11 KWNS 181705
SWOMCD
SPC MCD 181705
VAZ000-NCZ000-WVZ000-TNZ000-181900-
MESOSCALE DISCUSSION 1707
NWS STORM PREDICTION CENTER NORMAN OK
1205 PM CDT FRI JUL 18 2025
AREAS AFFECTED...2NORTH CAROLINA INTO VIRGINIA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 181705Z - 181900Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...THUNDERSTORMS MOVING OFF THE SOUTHERN APPALACHIANS WILL
INTENSIFY AS THEY MOVE INTO NORTH CAROLINA AND VIRGINIA AND MAY
PRODUCE SEVERAL SWATHS OF DAMAGING WIND. WATCH ISSUANCE IS EXPECTED
IN THE COMING HOURS TO ADDRESS THIS THREAT.
DISCUSSION...LATEST GOES IMAGERY SHOWS INCREASING DEPTH AND COVERAGE
OF CONVECTIVE TOWERS WITH OCCASIONAL LIGHTNING FLASHES WITHIN A
BROAD CUMULUS FIELD WITHIN THE SOUTHERN APPALACHIANS LIKELY DRIVEN
BY A COMBINATION OF INCREASING OROGRAPHIC ASCENT AND WEAK LIFT AHEAD
OF A DECAYING MCV. BASED ON RECENT RAP MESOANALYSIS, MODIFIED
FORECAST SOUNDINGS, AND AREAS OF LINGERING LOW/MID-LEVEL STRATUS,
SOME RESIDUAL INHIBITION REMAINS ACROSS THE REGION, BUT THIS SHOULD
QUICKLY ERODE THROUGH 19 UTC AS TEMPERATURES CLIMB INTO THE UPPER
80S/LOW 90S. THUNDERSTORM DEVELOPMENT IS EXPECTED AROUND THIS TIME
WITHIN/IN PROXIMITY TO THE HIGHER TERRAIN AS MLCIN IS REMOVED AND
GLANCING ASCENT AHEAD OF A MID-LEVEL TROUGH OVER THE GREAT LAKES
OVERSPREADS THE REGION.
MODERATE WESTERLY MID-LEVEL FLOW WILL SUPPORT STORM PROPAGATION INTO
VA/NC. THE COMBINATION OF WARM SURFACE TEMPERATURES AND SEASONABLY
MOIST CONDITIONS DOWNSTREAM (DEWPOINTS IN THE MID TO UPPER 70S) WILL
SUPPORT MLCAPE VALUES BETWEEN 2000-3000 J/KG BY PEAK HEATING.
CONSEQUENTLY, THUNDERSTORM SHOULD INTENSIFY AS THEY MOVE INTO THIS
ENVIRONMENT. GOES-DERIVED WIND ESTIMATES SHOW 30-35 KNOT FLOW
BETWEEN 6-7 KM AGL ACROSS NORTHERN VA, WHICH APPEARS TO BE SLIGHTLY
STRONGER THAN ANTICIPATED BY RECENT FORECAST GUIDANCE AND SHOULD BE
ADEQUATE FOR ORGANIZED CLUSTERS, AND PERHAPS A FEW ORGANIZED
DISCRETE CELLS, GIVEN WEAK LOW-LEVEL WINDS. WHILE A FEW INSTANCES OF
LARGE HAIL ARE POSSIBLE (MAINLY OVER CENTRAL VA WHERE MID-LEVEL FLOW
IS SLIGHTLY STRONGER), THE PREDOMINANT THREAT SHOULD BE
DAMAGING/SEVERE WINDS GIVEN STEEPENING NEAR-SURFACE LAPSE RATES,
HIGH PWAT VALUES, AND 20-25 K THETA-E DEFICITS, WHICH WILL ALL FAVOR
STRONG TO SEVERE DOWNBURSTS. DAMAGING WIND SWATHS SHOULD BECOME MORE
PROBABLE THROUGH MID/LATE AFTERNOON AS ORGANIZED CLUSTERS BEGIN TO
MATERIALIZE. WATCH ISSUANCE IS EXPECTED IN THE COMING HOURS TO
ADDRESS THIS CONCERN.
..MOORE/SMITH.. 07/18/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...MRX...
LAT...LON 36378194 38437897 38587840 38577789 38437748 38157723
37837699 37567687 37317681 36907684 36317719 35867766
35707824 35607868 35587939 35648109 35728156 35898189
36068204 36188208 36378194
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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