817
FXUS62 KRAH 170720
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
320 AM EDT SAT MAY 17 2025
SYNOPSIS
A COLD FRONT APPROACHING THE SOUTHERN APPALACHIANS THIS MORNING WILL
PUSH EAST AND SOUTHEAST ACROSS NORTH CAROLINA THIS AFTERNOON AND
ESPECIALLY TONIGHT AND THEN STALL ACROSS SOUTH CAROLINA AND GEORGIA
ON SUNDAY. COOLER AND DRIER HIGH PRESSURE WILL EXTEND INTO THE
REGION ON SUNDAY AND MONDAY. THE FRONT WILL LIFT NORTH ACROSS THE
CAROLINAS AS A WARM FRONT ON TUESDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 310 PM FRIDAY...
* THERE IS STILL A FAIR BIT OF UNCERTAINTY, HOWEVER A CONDITIONAL
THREAT FOR ISOLATED STRONG STORMS SAT AFT/EVE REMAINS.
ALOFT, THE SUB-TROPICAL RIDGE WILL REMAIN SUPPRESSED WELL SOUTH OF
THE AREA AS A CLOSED LOW TRACKS EWD ACROSS THE SRN/ERN GREAT LAKES
AND NORTHEAST US SAT/SAT NIGHT. A COUPLE OF SHORTWAVE DISTURBANCES
WITHIN THE ATTENDANT TROUGH WILL MOVE ACROSS THE REGION ON SAT
BEFORE THE TROUGH SHIFTS EWD OUT OF THE AREA SAT NIGHT. AT THE
SURFACE, THE PARENT LOW WILL OCCLUDE OVER THE GREAT LAKES ON SAT,
WHILE A SECONDARY LOW DEVELOPS OVER THE NORTHEAST US. THE ATTENDANT
COLD FRONT SHOULD PROGRESS EWD ACROSS THE AREA SAT AFT/EVE AS THE
SECONDARY LOW LIFTS NEWD ALONG THE NEW ENGLAND COAST.
UNCERTAINTY: THE BIGGEST UNCERTAINTY CONTINUES TO BE WHETHER THE
CONVECTION EXPECTED TO MOVE ACROSS THE MID-MS AND TN VALLEY REGIONS
TONIGHT, WILL HOLD TOGETHER AND MOVE INTO THE AREA EARLY SAT. AND IF
IT DOES MOVE INTO THE AREA, HOW LONG IT WILL HOLD TOGETHER. THEN,
HOW MUCH THE SHOWERS AND ASSOCIATED CLOUD COVER WILL STABILIZE THE
ATMOSPHERE AND/OR LIMIT DESTABILIZATION DURING THE AFT/EVE, THUS
IMPACTING WHETHER SHOWERS WILL RE-DEVELOP ALONG THE FRONT AND MOVE
ACROSS THE AREA SAT EVE/NIGHT. LATEST HI-RES GUIDANCE CONSENSUS HAS
THE SHOWERS/ISO STORMS HOLDING TOGETHER AND MOVING INTO THE WESTERN
PIEDMONT AROUND DAYBREAK SAT, THEN WEAKENING AND/OR DISSIPATING
SOMEWHERE OVER CENTRAL NC SAT MORN.
CONVECTION: FORECAST SOUNDINGS OFF THE NAM SHOW DESTABILIZATION
ACROSS MUCH OF THE AREA (ALBEIT BRIEFLY IN THE NW), WITH HIGHEST
CAPE VALUES ACROSS THE SANDHILLS AND COASTAL PLAIN DURING THE
AFT/EVE. MAX MUCAPE AROUND 2000 J/KG WITH EFFECTIVE SHEAR AROUND 40
KTS AT KFAY AND KRWI (AND BRIEFLY AT KRDU). ADDITIONALLY, WITH 25-35
KTS AT THE TOP OF THE MIXED LAYER, WIND GUSTS IN THAT RANGE WILL BE
POSSIBLE UNTIL THE NOCTURNAL INVERSION SETS UP SAT EVE. ADDITIONAL
SHOWERS/STORMS COULD DEVELOP DURING THE AFT/EVE ALONG/AHEAD OF THE
FRONT IF ENOUGH DESTABILIZATION IS REALIZED, AND COULD RESULT IN
STRONG WIND GUSTS AND POSSIBLY SOME HAIL. HOWEVER, THERE IS STILL
SOMEWHAT LOW CONFIDENCE IN TIMING, LOCATION, AND COVERAGE OF THAT
THREAT, IF IT MATERIALIZES.
TEMPERATURES: ALSO DEPENDENT ON WHAT HAPPENS WITH THE EARLY
CONVECTION SAT MORN, BUT FOR NOW EXPECT HIGHS RANGING FROM MID 80S
NW TO LOW 90S SE. BASED ON CURRENT TIMING OF THE FRONT, EXPECT LOWS
TO RANGE FROM LOW 60S NW TO UPPER 60S SE.
SHORT TERM /SUNDAY AND SUNDAY NIGHT/
AS OF 320 AM SATURDAY...
* WARM, BUT DRIER WITH GUSTY NORTHWESTERLY WINDS DURING THE
AFTERNOON.
SUNDAY WILL LIKELY BE LARGELY QUIET BEHIND THE FRONTAL PASSAGE FROM
SATURDAY NIGHT. THE INCOMING AIRMASS ISN'T PARTICULARLY MUCH COOLER,
BUT IT WILL BE NOTICEABLY DRIER AS DEW POINTS DROP INTO THE MID 50S.
MOMENTUM JUST ABOVE A SHALLOW INVERSION SUN MORNING WILL QUICKLY MIX
OUT AND PRODUCE SOME GUSTY WINDS 15 TO 25 MPH AS TEMPERATURES RISE
INTO THE 80S, NEAR 90 DEGREES ACROSS THE NC/SC BORDER. CONVECTIVE
DEBRIS AND REMNANT MCVS FROM UPSTREAM STORMS RIDING THE NOW
STATIONARY FRONT TO OUR SOUTH, SHOULD RESULT IN A MOSTLY CLOUDY DAY
AS MULTI-LAYERED CLOUDS STREAM ACROSS THE AREA. LOWS WILL SETTLE IN
THE 60S OUTSIDE OF THE FAR NORTHERN PIEDMONT WHERE UPPER 50S WILL BE
POSSIBLE.
.
LONG TERM /MONDAY THROUGH FRIDAY/
AS OF 320 AM SATURDAY...
* A SHARPENING WARM FRONT LIFTING TROUGH THE FORECAST AREA WILL
BRING UNSETTLED WEATHER THROUGH WEDNESDAY.
* COOLER AND DRIER WEATHER EXPECTED THURSDAY AND FRIDAY BEHIND A
COLD FRONTAL PASSAGE LATE WEDNESDAY.
A COUPLE MID-LEVEL CLOSED LOWS SITUATED OVER THE NORTHERN PLAINS AND
THE NORTHEAST WILL CREATE BROAD SHORTWAVE RIDGING FROM THE GULF
COAST UP THROUGH THE GREAT LAKES AND EXTEND OUT OVER THE SOUTHEAST.
THE STALLED BOUNDARY OVER GA/SC MON MORNING IS EXPECTED TO RIPPLE
NORTHWARD THROUGH THE LATE AFTERNOON, BUT HOW FAR NORTH IS FAIRLY
UNCERTAIN. SOUTH OF THIS FRONT WILL EXIST A MODERATELY UNSTABLE
AIRMASS WHERE DEW POINTS IN THE MID 60S WILL CONTRIBUTE TO 1000-2000
J/KG OF SBCAPE. MOST DETERMINISTIC GUIDANCE HAS A CONVECTIVE
INDUCED DISTURBANCE RIDING THE RIDGE MON AFTERNOON AND INTO THE
SOUTHEAST BY PEAK HEATING WITH ENHANCED WESTERLIES CONTRIBUTING TO
30 TO 40 KTS OF 0-6KM SHEAR. THE POSITION OF THE FRONT RIPPLING
NORTHWARD MON AFTERNOON WILL DELINEATE THE NORTHWARD EXPECT OF
SHOWERS/STORMS THROUGH MON EVENING.
BY TUES MORNING, THE WARM FRONT WILL CONTINUE TO LIFT FURTHER INTO
OUR AREA AND SHARPEN AS IT MEETS A BACKDOOR FRONT SLIDING DOWN
THROUGH THE MID-ATLANTIC. FRONTOGENETIC FORCING AND STRENGTHENING
WAA ALOFT WILL CONTRIBUTE TO BLOSSOMING AREA OF RAIN AND EMBEDDED
SHOWERS/STORMS ALONG AND NORTH OF THIS FRONT TUES EVENING AND
OVERNIGHT. THIS REGIME SHOULD SLOWLY LIFT INTO VA INTO WED MORNING
WHICH MAY LEAD TO A BRIEF LULL IS PRECIPITATION UNTIL A COLD FRONTAL
PASSAGE BRINGS ANOTHER ROUNDS OF SHOWERS AND POTENTIAL STORMS.
NOTICEABLY COOLER AIR WILL SPREAD INTO THE SOUTHERN MID-ATLANTIC
BEHIND THIS FRONTAL PASSAGE WITH ITS SOURCE REGION STEMMING FROM
CENTRAL QUEBEC WHERE A MARITIME POLAR AIRMASS IS PROGGED TO LOCATED.
COOLER AND MOSTLY DRIER WEATHER IS EXPECTED TO CONTINUE THROUGH
FRIDAY WHERE HIGHS ARE FORECAST TO BE 5 TO 10 DEGREES BELOW NORMAL.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
AS OF 255 AM SATURDAY...
VFR CONDITIONS ARE NOTED ACROSS CENTRAL NC EARLY THIS MORNING UNDER
A VEIL OF HIGH CIRRUS CLOUDS WITH CEILINGS AROUND 20KFT. A BAND OF
THUNDERSTORMS THAT MOVED ACROSS THE OH AND TN VALLEYS ON FRIDAY
AFTERNOON CONTINUES TO MARCH EAST AND WAS MOVING ACROSS THE WESTERN
SLOPES OF THE SOUTHERN APPALACHIANS AT AROUND 06Z. THIS BAND OF
CONVECTION IS FORECAST TO MOVE QUICKLY EAST AND LIKELY WEAKEN AS IT
MOVES EAST OF THE MOUNTAINS INTO THE NC FOOTHILLS DURING THE PREDAWN
HOURS. THE CONVECTION SHOULD ARRIVE IN THE TRIAD TERMINALS BETWEEN
09-12Z WITH A THREAT OF STRONG GUSTY WINDS OF 35KTS IN A FEW OF THE
THUNDERSTORMS ALONG WITH VSBY AND CIG RESTRICTIONS. THE CONVECTION
SHOULD SHIFT EAST AND SOUTHEAST AND WEAKEN A BIT, REACHING THE
TRIANGLE AREA BETWEEN 10 AND 13Z. THE CONVECTION WILL LIKELY WEAKEN
TO JUST SHOWERS AS THEY MOVE INTO THE FAYETTEVILLE AND ROCKY MOUNT
AREAS AS JUST SHOWERS BETWEEN 11 AND 15Z. AFTER THE INITIAL BAND OF
CONVECTION SHIFTS SOUTHEAST OF THE AREA, GENERALLY VFR CONDITIONS
ARE EXPECTED WITH WEST WINDS WILL INCREASE DURING THE DAY WITH WINDS
OF 15KTS AND GUSTS OF 25 TO 35KTS AT TIMES LATE THIS MORNING AND
THIS AFTERNOON. FAIR WEATHER IS EXPECTED TONIGHT WITH WINDS BECOMING
LIGHT WESTERLY AT 5 TO 10 KTS.
PERIODS OF LLWS ARE EXPECTED EARLY THIS MORNING AHEAD OF THE
CONVECTION WITH A 40 TO 45KT SOUTHWESTERLY LOW LEVEL JET. THE LLWS
THREAT WILL DISSIPATE AS THE CONVECTION MOVES ACROSS THE AREA THIS
MORNING. HOWEVER, ANOTHER PERIOD OF LLWS IS POSSIBLE THIS EVENING AS
SURFACE WINDS RELAX BUT A STRONG WESTERLY LOW LEVEL JET OF AROUND
50KTS MAY RESULT IN AREAS OF LLWS MAINLY FROM RALEIGH EAST UP UNTIL
AROUND MIDNIGHT.
LOOKING BEYOND THE 24 HOUR TAF PERIOD: MAINLY FAIR WEATHER IS
EXPECTED FOR SUNDAY AND INTO MONDAY WITH A THREAT OF MAINLY
AFTERNOON AND EVENING STORMS ON TUESDAY AND WEDNESDAY. AREAS OF LATE
NIGHT AND EARLY MORNING LOW STRATUS AND FOG IS POSSIBLE ON TUESDAY
AND ESPECIALLY WEDNESDAY. -BLAES
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BLAES
NEAR TERM...KC
SHORT TERM...SWIGGETT
LONG TERM...SWIGGETT
AVIATION...BLAES
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