538
FXUS62 KRAH 131404
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1003 AM EDT TUE MAY 13 2025
SYNOPSIS
A SLOW MOVING UPPER LOW CENTERED OVER THE TENNESSEE VALLEY WILL
SLOWLY LIFT NORTHEAST INTO THE OHIO VALLEY AND MID-ATLANTIC STATES
THROUGH WEDNESDAY, BRINGING WET AND UNSETTLED WEATHER TO THE REGION.
THE LOW WILL WEAKEN AND MOVE NE OF THE AREA BY LATE WEEK WITH HOT
AND HUMID WEATHER TO FOLLOW.
NEAR TERM /THROUGH TONIGHT/
AS OF 1003 AM TUESDAY...
* FLOODING THREAT LINGERS THROUGH THE EARLY EVENING
* MARGINAL/LEVEL 1 RISK OF OF SEVERE STORMS THROUGH THE EARLY EVENING
THE BULK OF HEAVIER RAIN FROM THE OVERNIGHT HOURS HAS SHIFTED INTO
EASTERN NC AND THE CHESEAPEAKE AREA THIS MORNING. BEHIND THIS BAND,
A LULL IN PRECIPITATION IS EXPECTED THROUGH ABOUT MID TO LATE
MORNING. AS WE PIVOT INTO THE AFTERNOON, HOWEVER, BREAKS IN THE
CLOUDS WILL INCREASE INSTABILITY AND GENERATE SCATTERED TO NUMEROUS
SHOWERS AND STORMS. LINGERING PWAT IS STILL EXPECTED TO BE QUITE
ANOMALOUS, AND AS SUCH THERE REMAINS A CHANCE FOR ISOLATED FLASH
FLOODING ESPECIALLY FOR URBAN AREAS WHERE REPEATED HEAVY RAIN
OCCURS. THINK THE BEST CHANCES FOR FLASH FLOODING WOULD BE IN THE
CHATHAM/ORANGE/DURHAM COORIDOR. THESE AREAS RECEIVED A GOOD AMOUNT
OVER THE PAST 24 HOURS, AND LATEST CAM GUIDANCE IS PINPOINTING THE
CENTRAL TO NORTHERN PIEDMONT AS HAVING GOOD COVERAGE TODAY.
OBVIOUSLY, ANY URBAN COORIDOR STILL IN THE FLOOD WATCH AREA COULD
SEE ISOLATED FLASH FLOODING AS WELL.
SEVERE WEATHER WISE, THE STRONG LOW-LEVEL HELICITY THAT PROMPTED
MULTIPLE TORNADO WARNINGS LAST NIGHT AND OVERNIGHT HAS LARGELY
SHIFTED EAST OF OUR AREA THIS MORNING. HOWEVER, HREF GUIDANCE
SUGGESTS ANYWHWERE FROM 100 TO 150 M2S2 OF LOW-LEVEL EFFECTIVE
HELICITY LINGERING ACROSS THE COASTAL PLAIN THROUGH MUCH OF TODAY
AND TONIGHT. THE 00Z HREF RUN CLUSTERED SOME LOW-LEVEL HELICITY (0-
3 KM) SWATHS IN OUR NORTHERN COASTAL PLAIN AS WELL. THUS, CAN'T
FULLY RULE OUT AN ISOLATED QUICK SPIN UP TORNADO AGAIN TODAY FOR
THOSE IN THE COASTAL PLAIN.
OTHERWISE, AS WAS MENTIONED IN THE PREVIOUS DISCUSSION BELOW,
ISOLATED DAMAGING WIND GUSTS AND LARGE HAIL COULD BE POSSIBLE IN ANY
DEEPER CONVECTION LATER TODAY GIVEN DECENT DEEP LAYER SHEAR.
PREVIOUS DISCUSSION AS OF 340 AM TUESDAY...
A SLOW MOVING UPPER LOW WILL GRADUALLY SHIFT EAST-NORTHEASTWARD,
FROM THE MID SOUTH THIS MORNING TO THE SOUTHERN/CENTRAL APPALACHIANS
TONIGHT. SHORTWAVE TROUGH ENERGY SWINGING AROUND THE BASE OF THE
ATTENDANT UPPER TROUGH WILL PIVOT NE ACROSS CENTRAL NC LATER TODAY.
MEANWHILE AT THE SURFACE, A FRONTAL TRIPLE POINT WILL MOVE NE
THROUGH THE AREA.
THE LOW-LEVEL WARM MOIST CONVEYOR AND ASSOCIATED MAIN CONVECTIVE
BAND THAT CURRENTLY EXTENDS ACROSS THE EASTERN HALF OF THE FORECAST
AREA WILL SHIFT EAST AND OUT OF THE AREA BETWEEN 12-15Z. UNTIL IT
DOES SO, 0-1KM HELICITY OF 200-300 M/S AND RELATED STRONGLY CURVED
HODOGRAPHS WILL SUPPORT A LOW END THREAT OF A WEAK AND BRIEF
TORNADO, MAINLY ACROSS THE EASTERN/COASTAL PLAIN COUNTIES WHERE WEAK
INSTABILITY EXIST.
FOLLOWING A BRIEF LULL, DURING WHICH TIME CLOUD BASES WILL LIFT AND
BREAKS IN CLOUD COVER WILL EVOLVE OWING TO ENTRAINMENT OF DRY AIR
ALOFT, MODERATE DESTABILIZATION WITH MLCAPE OF 1500-2000 J/KG SHOULD
BE REALIZED BY THE AFTERNOON. THIS COUPLED WITH WEAK MID-LEVEL
HEIGHT FALLS AND DPVA SHOULD SUPPORT SCATTERED SHOWERS AND
THUNDERSTORMS. DEEP LAYER SHEAR OF 30-35 KTS ALONG WITH FAVORABLE
DCAPE ENVIRONMENT WILL SUPPORT A RISK OF A FEW SEVERE STORMS WITH
SEVERE HAIL AND DAMAGING WINDS THE PRIMARY THREAT.
ADDITIONALLY, AFTER HEAVY RAIN ON MONDAY, AREAS MAY BE MORE
SENSITIVE TO FLOODING GIVEN HIGHER SOIL MOISTURE, AND ISOLATED TO
SCATTERED FLASH FLOODING CONCERNS REMAIN, MAINLY ACROSS EASTERN AND
NORTHEASTERN PORTIONS OF NORTH CAROLINA.
SHOWERS AND STORMS WILL DIMINISH OVERNIGHT, BUT PARTIAL CLEARING
OVERNIGHT MAY LEAD TO FOG DEVELOPMENT, POTENTIALLY DENSE BETWEEN 06-
12Z, ESPECIALLY ALONG AND NORTH OF HIGHWAY 64.
HIGHS TODAY RANGING FROM MID/UPPER 70S NORTH LOWER 80S SE. LOWS
TONIGHT IN THE 60S.
SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/
AS OF 540 AM TUESDAY...
A MID/UPR-LEVEL CYCLONE CENTERED OVER THE TN VALLEY WILL BECOME
ELONGATED BY, AND DEVELOP A NEW CENTER WITHIN, A SIGNIFICANT
SHORTWAVE PERTURBATION THAT WILL PIVOT NWD FROM THE SRN APPALACHIANS
THIS MORNING TO MI BY WED. THE VORTICITY MAXIMA AND SHORTWAVE
TROUGH RELATED TO THE CYCLONE'S INITIAL CENTER OVER THE TN VALLEY
WILL PIVOT NEWD AND ACROSS VA AND NRN NC ON WED, AS WILL ITS
ASSOCIATED MINUS 14 TO 15 C COLD POOL AT 500 MB.
AT THE SURFACE, A TROUGH WILL LINGER OVER THE SRN MIDDLE ATLANTIC,
WITH SEASONABLY MOIST LOW-LEVELS CHARACTERIZED BY SURFACE DEWPOINTS
MOSTLY IN THE LWR-MID 60S.
DIURNAL HEATING OF THE SEASONABLY MOIST-LOW LEVELS, BENEATH THE
AFOREMENTIONED COOL TEMPERATURES ALOFT, WILL ERODE WEAK CONVECTIVE
INHIBITION BY MIDDAY AND SUPPORT THE PROBABLE DEVELOPMENT OF
GENERALLY NUMEROUS SHOWERS AND STORMS WITHIN A MODERATELY UNSTABLE
AIRMASS THROUGH THE AFTERNOON. THE COOL TEMPERATURES ALOFT AND
RELATIVELY LOW FREEZING LEVELS BETWEEN 9500-11500 FT AGL WILL FAVOR
MOSTLY SMALL HAIL, BUT MODEST, ~25-30 KTS OF MID-LEVEL FLOW MAY
SUPPORT TRANSIENT ROTATION SUPPORTIVE OF A FEW INSTANCES OF
MARGINALLY SEVERE HAIL AND PERHAPS A LOCALLY DAMAGING WIND GUST.
SINCE CONVECTION WILL BE LARGELY DIURNALLY-DRIVEN, COVERAGE AND
INTENSITY SHOULD DIMINISH THROUGH THE EVENING. TEMPERATURES WILL BE
GENERALLY PERSISTENCE ONES, IN THE MID 70S TO LWR 80S FOR HIGHS AND
LWR-MID 60S FOR LOWS.
LONG TERM /THURSDAY THROUGH MONDAY/
AS OF 545 AM TUESDAY...
NO CHANGE TO THE PREVIOUS FORECAST RATIONALE BELOW
SHORTWAVE RIDGING WILL BUILD TO OUR WEST ON THURSDAY AND MOVE
OVERHEAD ON THURSDAY NIGHT, WITH ASSOCIATED HEIGHT RISES. MODEL
SOUNDINGS INDICATE THIS WILL BRING A DECENT CAPPING INVERSION THAT
SHOULD LIMIT CONVECTIVE DEVELOPMENT, BUT STILL CAN'T RULE OUT A FEW
ISOLATED SHOWERS/STORMS AS GOOD SURFACE HEATING AND CONTINUED LOW-
LEVEL MOISTURE WILL RESULT IN WEAK TO MODERATE DESTABILIZATION ONCE
AGAIN. FOR NOW ONLY HAVE SLIGHT TO LOW CHANCE POPS (HIGHEST EAST).
HIGH TEMPERATURES WILL TURN ABOVE AVERAGE, IN THE MID-TO-UPPER-80S.
LOWS THURSDAY NIGHT WILL ONLY DROP INTO THE MID-TO-UPPER-60S.
THE FIRST PART OF FRIDAY COULD BE DRY AS WELL AS WE ARE STILL UNDER
THE INFLUENCE OF THE SHORTWAVE RIDGING PUSHING TO OUR EAST, BUT BY
LATE FRIDAY AND SATURDAY, WE WILL EXPERIENCE SOME WEAK MID-LEVEL
HEIGHT FALLS FROM THE NEXT CLOSED LOW THAT MOVES EAST ACROSS THE
UPPER GREAT LAKES. A SURFACE TROUGH WILL ALSO BE IN PLACE ACROSS OUR
REGION. SO PRECIPITATION CHANCES SHOULD INCREASE, AND ISOLATED TO
SCATTERED CONVECTION WILL BE POSSIBLE. GIVEN STRONG DESTABILIZATION
OF 2000-3000+ J/KG OF CAPE SHOWN ON BOTH THE ECMWF AND GFS, ALONG
WITH 40-50 KTS OF BULK SHEAR, STRONG TO SEVERE STORMS WILL BE
POSSIBLE. TEMPERATURES WILL ALSO BE A CONCERN, WITH HIGHS IN THE
UPPER-80S TO MID-90S ON FRIDAY AND SATURDAY. DEW POINTS WILL RISE TO
THE UPPER-60S AND POSSIBLY LOWER-70S BOTH DAYS, SO HEAT INDICES WILL
BE A CONCERN, ESPECIALLY ON FRIDAY WHEN THEY ARE FORECAST TO REACH
THE MID-90S TO 100 FROM THE TRIANGLE TO THE SOUTH AND EAST.
A COLD FRONT LOOKS TO MOVE THROUGH THE REGION ON SATURDAY NIGHT,
THOUGH THERE IS STILL SOME UNCERTAINTY ON ITS TIMING AND PLACEMENT.
LOOKING ALOFT, THE FLOW WILL TURN MORE NORTHWESTERLY AS THE MID-
LEVEL CYCLONE PUSHES FARTHER EAST AND RIDGING BUILDS OVER THE
CENTRAL US. FOR NOW EXPECT A DRYING TREND WITH ONLY SLIGHT CHANCE
POPS ON SUNDAY AND MONDAY. THE BEST CHANCE OF ANY CONVECTION WOULD
BE IN THE SOUTH DEPENDING ON WHERE THE FRONT GETS HUNG UP. FORECAST
HIGHS DECREASE CLOSER TO NORMAL BOTH DAYS.
AVIATION /11Z TUESDAY THROUGH SATURDAY/
AS OF 700 AM TUESDAY...
MAIN CONVECTIVE BAND WILL SHIFT EAST OF THE AREA BETWEEN 12-15Z.
EXPECT A BRIEF LULL IN PRECIPITATION, WHICH SHOULD ALLOW THIS WILL
FOR BREAKS IN CLOUD COVER AND GRADUAL LIFTING TO VFR THROUGH THE
AFTERNOON, OWING TO MID-LEVEL DRY AIR ENTRAINMENT OVER THE REGION.
HOWEVER, AIRMASS DESTABLIZATION WILL ALLOW FOR THE RE-DEVELOPMENT OF
SCATTERED SHOWERS AND STORMS AND ASSOCIATED SUB-VFR RESTRICTIONS
THROUGH THE AFTERNOON AND EVENING.
SHOWERS AND STORMS WILL DIMINISH OVERNIGHT, BUT PARTIAL CLEARING
OVERNIGHT MAY LEAD TO FOG DEVELOPMENT, POTENTIALLY DENSE BETWEEN 06-
12Z, MAINLY ACROSS THE NORTHERN TERMINALS.
OUTLOOK: CHANCES FOR DIURNAL SCATTERED SHOWERS AND STORMS WILL
CONTINUE THROUGH THE PERIOD. MORNING FOG AND LOW STRATUS WILL BE
POSSIBLE EACH MORNING, ESPECIALLY IN AREAS THAT RECEIVED SIGNIFICANT
RAINFALL THE PREVIOUS DAY.
RAH WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ007>011-024>028-041>043-078-
089.
SYNOPSIS...BADGETT
NEAR TERM...LUCHETTI/CBL
SHORT TERM...MWS
LONG TERM...DANCO
AVIATION...CBL
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