524
FXUS62 KRAH 210523
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
125 AM EDT THU MAY 21 2026
WHAT HAS CHANGED
* THE NBM MEAN KEEPS TRENDING COOLER FOR FRI COMPARED TO ITS
PREVIOUS ITERATIONS, AND GIVEN THE COLD AIR DAMMING REGIME, WILL
CONTINUE TO FAVOR THE COOLER NBM MEMBERS, ESPECIALLY IN THE
PIEDMONT.
* CONFIDENCE IS GROWING THAT THE WEDGE WILL PERSIST THROUGH SAT IN
THE NW PIEDMONT.
* THERE ARE GROWING CONCERNS FOR ISOLATED HEAVY RAINFALL, INCLUDING
LATE TODAY THROUGH TONIGHT OVER THE W PIEDMONT AND SANDHILLS. THIS
THREAT COULD LINGER IN SOME AREAS INTO EARLY NEXT WEEK.
KEY MESSAGES
AS OF 125 AM THURSDAY...
1) AREAS OF STRATUS AND PATCHY FOG ARE LIKELY IN THE SOUTHEAST CWA
EARLY THIS MORNING.
2) A WEDGE SETUP WILL LEAD TO COOL TEMPS FRI, PARTICULARLY IN THE
PIEDMONT, AND CHANCES ARE INCREASING THAT IT WILL LINGER INTO SAT IN
THE NW PIEDMONT.
2) A WET PATTERN STARTS LATER TODAY, WITH ABOVE NORMAL RAIN CHANCES
EXPECTED THROUGH THE BEGINNING OF NEXT WEEK. WHILE IT WON'T BE
RAINING THE ENTIRE TIME AT ANY GIVEN LOCATION, POCKETS OF HEAVY
DOWNPOURS WILL BE POSSIBLE, INCLUDING LATE TODAY AND TONIGHT.
DISCUSSION
AS OF 125 AM THURSDAY...
KEY MESSAGE 1... AREAS OF STRATUS AND PATCHY FOG ARE LIKELY IN THE
SOUTHEAST CWA EARLY THIS MORNING.
SURFACE WINDS WILL BE GENERALLY LIGHT THROUGH DAYBREAK, WITH A FLUX
OF HIGHER DEWPOINTS INTO OUR SE LEADING TO LOW DEWPOINT DEPRESSIONS.
NOT ONLY IS THIS OVERALL PATTERN FAVORABLE FOR LOW STRATUS AND/OR
PATCHY FOG, THIS OCCURRENCE IS SUPPORTED BY MULTIPLE PIECES OF HIGH-
RES GUIDANCE, AS WELL AS BY PERSISTENCE, GIVEN THAT THE SE SAW LOW
STRATUS LAST NIGHT. THE LATEST HREF SUITE APPEARS A BIT BULLISH,
BRINGING LOW CIGS WELL NORTHWEST INTO THE HWY 1 CORRIDOR, AND WHILE
THIS ISN'T OUT OF THE QUESTION, THE HIGHEST CHANCES FOR STRATUS/FOG
SHOULD BE RESTRICTED TO THE FAR SE. ANY STRATUS/FOG SHOULD LIFT AND
MIX/DISPERSE BY LATE MORNING.
KEY MESSAGE 2... A WEDGE SETUP WILL LEAD TO COOL TEMPS FRI,
PARTICULARLY IN THE PIEDMONT, AND CHANCES ARE INCREASING THAT IT
WILL LINGER INTO SAT IN THE NW PIEDMONT.
A COLD AIR DAMMING EVENT IS LOOKING LIKE A NEAR CERTAINTY FOR AT
LEAST FRI AND PERHAPS HOLDING ON INTO SAT AS WELL. TODAY'S FRONT
WILL SETTLE ALONG THE SOUTHERN AND EASTERN EDGES OF THE CWA LATE
TONIGHT, WITH COOL HIGH PRESSURE NOSING IN FROM THE NORTH AS ITS
CENTER SHIFTS FROM THE N GREAT LAKES ACROSS NEW ENGLAND TO JUST OFF
THE NORTHEAST COAST TODAY THROUGH SAT. MODELS KEEP THIS HIGH ONLY
MODESTLY PROGRESSIVE, WITH SLOWING/ANCHORING CONFLUENT FLOW ATOP IT,
AND IT REMAINS OF DECENT STRENGTH, AROUND 1032 MB CENTRAL PRESSURE
AT ITS PEAK, ALTHOUGH WE'RE UNLIKELY TO TAP INTO THE REALLY LOW
DEWPOINTS CURRENTLY AT ITS CORE. NEVERTHELESS, THE COMBINATION OF
COOL AIR ADVECTION WITH NE FLOW AND OVERRUNNING CLOUDS AND PRECIP
ALL FAVOR A CAD EVENT WITH WEDGING THROUGH THE PIEDMONT. HAVE KEPT
FRI HIGHS CLOSER TO THE NBM10PCT AND MEAN STATISTICAL GUIDANCE,
ESPECIALLY ACROSS THE N AND W PIEDMONT. THIS YIELDS HIGHS IN THE MID-
UPPER 60S IN THE NW AND NEAR THE VA BORDER, RANGING TO LOW-MID 80S
IN THE FAR S, INCLUDING MOSTLY 70S IN THE TRIANGLE. BY SAT, AS MID
LEVEL RIDGING RE-ASSERTS ITSELF OVER AND OFF THE SOUTHEAST COAST,
THE SURFACE/WEDGE FRONT WILL ATTEMPT TO PUSH N AND NW. BUT WITH THE
CENTER OF THE PARENT HIGH PAUSING JUST OFF THE NORTHEAST COAST
POTENTIALLY LEADING TO A CONTINUATION OF CAA INTO OUR NW, THE
RETREATING FRONT MAY STRUGGLE TO BREAK THROUGH THIS STABLE POOL. FOR
NOW, HAVE NUDGED HIGHS DOWNWARD IN THE NW PIEDMONT TO ABOUT A
CATEGORY LOWER THAN THE NBM DETERMINISTIC, BUT FURTHER DOWNWARD
ADJUSTMENTS MAY BE NEEDED IN LATER FORECASTS IF THE WEDGE REGIME
BECOMES PARTICULARLY STUBBORN.
KEY MESSAGE 3... A WET PATTERN STARTS LATER TODAY, WITH ABOVE NORMAL
RAIN CHANCES EXPECTED THROUGH THE BEGINNING OF NEXT WEEK. WHILE IT
WON'T BE RAINING THE ENTIRE TIME AT ANY GIVEN LOCATION, POCKETS OF
HEAVY DOWNPOURS WILL BE POSSIBLE, INCLUDING LATE TODAY AND TONIGHT.
AS WE'VE BEEN WIDELY ADVERTISING, WE ARE TRANSITIONING INTO AN
UNSETTLED AND WETTER PATTERN WITH FAIRLY HIGH RAIN CHANCES OVERALL
FOR SEVERAL DAYS, ALTHOUGH NOT EVERY SPOT WILL SEE RAIN EACH DAY.
SHOWERS AND SCATTERED STORMS ARE EXPECTED TO DEVELOP ALONG THE FRONT
ACROSS THE N STARTING THIS AFTERNOON, THEN SETTLE SE WITH THE FRONT
TONIGHT. POCKETS OF HEAVY RAINFALL ARE POSSIBLE THIS AFTERNOON
THROUGH TONIGHT, AS THE LATEST HREF PMM SHOWS HIGH (50-70%) CHANCES
FOR AN INCH IN 3 HRS LATER TODAY ROUGHLY N OF HWY 64, THEN ACROSS
MUCH OF THE S AND E CWA THIS EVENING INTO THE OVERNIGHT HOURS, ALL
AMIDST INCREASING PW TO WELL ABOVE NORMAL WITH STRENGTHENING SSW 850
MB FLOW. BY FRI, THE CHANCES FOR POCKETS OF HEAVY DOWNPOURS (AND
THUNDER) SHOULD BE RESTRICTED TO ALONG AND SE OF THE WEDGE FRONT IN
THE AFTERNOON THROUGH EARLY EVENING, WITH STRATIFORM RAIN MORE
LIKELY FURTHER NW OVER THE STABLE POOL. THEREAFTER, AS THE NARROW
MID LEVEL RIDGE WEAKENS FURTHER, WE'LL BE WITHIN A WEAKLY-PERTURBED
MID LEVEL SW FLOW FROM N MEXICO AND TX THROUGH THE MID SOUTH AND S
APPALACHIANS, WITH SHOTS OF MID LEVEL DPVA ACTING ON HIGH PW THAT
TRENDS TO 125-200% OF NORMAL. AND ONCE THE WEDGE FRONT FINALLY LIFTS
TO OUR N, WE'LL STAY WITHIN THE WARM SECTOR FOR MULTIPLE DAYS, WITH
PERSISTENT DEEP AND CONFLUENT LOW LEVEL MOIST ISENTROPIC UPGLIDE AT
295-305K SOURCED FROM BOTH THE GULF AND ATLANTIC.
THIS LONG AND WAVY SW MID LEVEL FLOW FROM N MEXICO INTO THE
CAROLINAS AND THE HIGH LOW-LEVEL MOISTURE FLUX ARE LIKELY TO PERSIST
THROUGH EARLY NEXT WEEK, AND OUR RAIN CHANCES ARE EXPECTED TO REMAIN
ABOVE NORMAL, PEAKING EACH AFTERNOON AND EVENING. WHILE THIS RAIN IS
MUCH NEEDED WITH OUR ONGOING DROUGHT CONDITIONS, THE RISK OF HIGH
RAIN RATES IN A SHORT PERIOD OF TIME RAISES CONCERNS FOR POTENTIAL
ISOLATED FLOODING, ESPECIALLY IF THERE IS RAPID RUNOFF ATOP THE HARD
PARCHED GROUND IN SOME AREAS. BY THE MIDDLE OF NEXT WEEK, WE'LL
TRANSITION TO AN OMEGA BLOCK PATTERN FROM THE BAHAMAS UP THROUGH
ONTARIO, SANDWICHED BETWEEN DEEP LOWS OVER THE ROCKIES AND OVER THE
CANADIAN MARITIMES. THIS MAY PUSH A FRONT BACK DOWN INTO THE AREA,
WHICH COULD PROLONG THIS WET PERIOD.
AVIATION /00Z THURSDAY THROUGH MONDAY/
AS OF 700 PM WEDNESDAY...
THERE IS HIGH CONFIDENCE IN VFR CONDITIONS TO START THE TAF PERIOD.
THE IMMEDIATE FORECAST CHALLENGE IS THE POTENTIAL FOR FOG OR STRATUS
THU MORNING OVER THE EASTERN TERMINALS OF RDU, FAY, AND RWI. AS WITH
THE PRIOR FORECAST, THERE IS RELATIVELY LOW CONFIDENCE IN THIS
THREAT. THE LATEST HIGH-RES GUIDANCE CONTINUES TO SHOW A HIGHER
POTENTIAL FOR IFR/MVFR STRATUS AT FAY/RWI, BUT THE SIGNAL IS NOT
CONSISTENT WITHIN THE INDIVIDUAL HREF MEMBERS. OUR LATEST THINKING
FAVORS THE BEST CHANCE OF SUB-VFR STRATUS AT RWI AND SECONDLY AT
FAY. THE LOWEST CONFIDENCE IS AT RDU. THE LATEST FORECAST IS LITTLE
CHANGED BUT DOES INCLUDE A PREVAIL MVFR CONDITION AT RWI UNTIL 13Z.
AN APPROACHING COLD FRONT AND AREA OF LOW PRESSURE WILL FAVOR THE
DEVELOPMENT OF SCATTERED SHOWERS AND STORMS THU AFTERNOON INTO THU
EVENING. STORM ARE EXPECTED TO DEVELOP UPSTREAM IN WESTERN NC AND
VA, SLOWLY ADVANCING SSE ALONG STORM OUTFLOWS. HREF MEMBERS INDICATE
THE GREATEST THREAT FOR STORMS AND RESTRICTIONS AT GSO/INT AND RDU
IN THE 19-00Z TIME FRAME AND THE LATEST FORECAST INCLUDES TEMPO
GROUPS FOR IFR CONDITIONS. STORMS MAY APPROACH RWI CLOSER TO THE END
OF THE PERIOD AND MAY NOT REACH FAY UNTIL LATE THU NIGHT. ONCE THE
FRONT MOVES THROUGH, IFR STRATUS IS EXPECTED, MAINLY AFTER THE TAF
PERIOD.
OUTLOOK: SCATTERED SHOWERS AND STORMS WILL PERSIST THURSDAY NIGHT
ALONG WITH GUSTY NELY SFC WINDS. SUB-VFR CEILINGS WILL DEVELOP POST-
FRONTAL THU NIGHT AND PERSIST POTENTIALLY INTO SAT OVER MOST
TERMINALS AS A CAD REGIME LOOKS TO SET UP OVER THE REGION. DAILY
SHOWER/STORM CHANCES WILL ALSO BE POSSIBLE THROUGH EARLY NEXT WEEK.
CLIMATE
RECORD HIGH TEMPERATURES:
MAY 21:
KRDU: 96/1941
KFAY: 99/1941
RECORD HIGH MINIMUM TEMPERATURES:
MAY 21:
KGSO: 67/2022
KRDU: 71/1898
KFAY: 71/2025
MAY 22:
KFAY: 73/2004
MAY 23:
KFAY: 72/2011
MAY 24:
KRDU: 70/2011
KFAY: 72/2000
MAY 25:
KGSO: 70/2019
KRDU: 71/2019
KFAY: 71/2019
MAY 26:
KGSO: 70/2019
KRDU: 73/2011
KFAY: 75/2004
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HARTFIELD
AVIATION...KREN
CLIMATE...RAH
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