200
FXUS62 KRAH 150459
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1259 AM EDT THU MAY 15 2025
SYNOPSIS
AN UPPER LEVEL TROUGH WILL MOVE THROUGH THE REGION THROUGH TONIGHT.
UPPER LEVEL DISTURBANCES MOVING ATOP AN UPPER LEVEL RIDGE BUILDING
ACROSS THE SE US WILL SUPPORT MAINLY DIURNAL SHOWERS AND STORMS AND
UNSEASONABLY HOT TEMPERATURES TO END THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 1259 AM THURSDAY...
* A DENSE FOG ADVISORY HAS BEEN ISSUED FOR NORTHERN AND CENTRAL
PORTIONS OF CENTRAL NC
QUICK UPDATE TO INCLUDE THE ISSUANCE OF A DENSE FOG ADVISORY
ACROSS THE NORTHERN HALF THE FORECAST AREA(ROUGHLY US 64 NORTH)
WHERE SATURATED SOILS AND RAIN-COOLED NIGHTTIME AIR HAS ALLOWED
DEWPOINT DEPRESSIONS TO FALL <2 DEGREES OR LESS ACROSS MUCH OF THIS
AREA.
PREVIOUS DISCUSSION..REGIONAL RADAR AND SATELLITE IMAGERY SHOWS
CONVECTION HAS WEAKENED AND EXITED CENTRAL NC WITH ONLY SOME
LINGERING TRAILING STRATIFORM RAIN OVER CUMBERLAND AND SAMPSON
COUNTY. VERY LOW STRATUS IS ALSO ALREADY SEEN BLOSSOMING OVER THE
NORTHERN PIEDMONT WHERE THE HEAVIEST RAIN OCCURRED EARLIER THIS
AFTERNOON. THE CONTINUED MOIST AIRMASS IN PLACE CHARACTERIZED BY DEW
POINTS IN THE LOW TO MID 60S WILL LIKELY SUPPORT PATCHY DENSE FOG.
THE AREAS IN WHICH IT WILL DEVELOP WILL LIKELY BE WHERE SKIES REMAIN
CLEAR AND AWAY FROM THE EXPANDING AREA OF STRATUS TO THE NORTH,
HOWEVER, THIS AREA MAY ALSO SEE SOME DENSE FOG AS IT GRADUALLY
LOWERS TOWARDS THE SURFACE BY DAYBREAK.
ADDITIONALLY, AN ELEVATED WARM FRONTAL ZONE STRETCHING FROM THE
LOWER OHIO VALLEY INTO THE SOUTHEAST IS EXPECTED TO GRADUALLY LIFT
NORTHWARD AND DEVELOP MOSTLY ELEVATED SHOWERS AND POSSIBLE STORMS
OVERNIGHT. LATEST CAM GUIDANCE SHOWS SHOWERS/STORMS DEVELOPING OVER
WESTERN NC AND UPSTATE SC AND DRIFTING INTO OUR REGION, MOSTLY
SCATTERED IN NATURE, AND DISSIPATING SHORTLY AFTER SUNRISE. LOWS
WILL SETTLE IN THE LOW TO MID 60S.
SHORT TERM /THURSDAY AND THURSDAY NIGHT/
AS OF 300 PM WEDNESDAY...
12Z GUIDANCE THIS MORNING HAS DONE LITTLE IN TERMS OF CHANGING OUR
THINKING ABOUT HOW THURSDAY WILL EVOLVE. THERE REMAINS UNCERTAINTY
WRT TO COVERAGE THURSDAY AFTERNOON, ESPECIALLY GIVEN THE INFLUENCE
OF THE APPROACHING UPPER RIDGE. IF CONVECTION DOES REACH CENTRAL NC,
IT STILL APPEARS TO BE MOST LIKELY OVER THE NORTHERN PIEDMONT AND
NORTHERN COASTAL PLAIN LATER IN THE DAY. DECIDED TO MAINTAIN JUST
CHANCE POPS IN THIS VICINITY CENTERED AROUND MID TO LATE AFTERNOON
AND EARLY EVENING. OTHERWISE, THE DESCRIPTION OF POTENTIAL HAZARDS
AND ASSOCIATED RATIONALE REMAINS ACCURATE FROM THE PREVIOUS
DISCUSSION LISTED BELOW.
PREVIOUS DISCUSSION FROM 430 AM...
DOWNSTREAM OF A MID/UPR-LEVEL CYCLONE THAT WILL DEVELOP AND DEEPEN
ACROSS THE NRN PLAINS AND UPR MS VALLEY, PROGRESSIVE SHORTWAVE
RIDGING FROM THE LWR MS TO OH VALLEYS AT THE START OF THE PERIOD
WILL MIGRATE EWD AND ACROSS THE MIDDLE AND SOUTH ATLANTIC THROUGH
12Z FRI. SEASONABLY STRONG NWLY TO WNWLY MID-LEVEL FLOW WILL RESULT
AND PREVAIL ACROSS THE SRN MIDDLE ATLANTIC AND CAROLINAS, AS WILL
WARM AIR ADVECTION MAXIMIZED IN THE 700-850 MB LAYER THAT WILL
PRECEDE THE ARRIVAL OF AN EXTENSIVE ELEVATED MIXED LAYER PLUME FROM
THE SRN PLAINS AND MEXICAN PLATEAU.
AT THE SURFACE, A WARM FRONT WILL STRENGTHEN AND RETREAT NEWD ACROSS
THE OH VALLEY AND VIRGINIAS, WHILE BROAD TROUGHING WILL OTHERWISE
REMAIN ACROSS THE SRN MIDDLE ATLANTIC AND CAROLINAS.
THE AFOREMENTIONED WAA REGIME MAY SUPPORT AN ONGOING AREA OF
ELEVATED CONVECTION OVER OR NEAR CNTL NC THU MORNING, BEFORE MOVING
EWD AND OFFSHORE THROUGH MIDDAY. THAT WAA REGIME, INCLUDING THROUGH
THE LOW-LEVELS WITH THE AFOREMENTIONED SURFACE WARM FRONTAL RETREAT,
WILL LIKELY SPREAD NWD ACROSS THE VIRGINIAS COINCIDENT WITH DAYTIME
HEATING. A SEPARATE AREA OF CONVECTION WILL PROBABLY RESULT AND
DEVELOP ALONG AND EAST OF THE BLUE RIDGE IN VA, WITH OTHER, MORE-
ISOLATED CELLS ACROSS THE NC NE PIEDMONT AND NRN COASTAL PLAIN - ALL
WITH A GENERALLY SEWD STORM MOTION THAT WOULD FAVOR SLIGHT TO LOW
CHANCE POP ROUGHLY ALONG AND NORTH OF I-40 DURING THE AFTERNOON-
EVENING. FORECAST HODOGRAPHS ARE ELONGATED AND CLOCKWISE-CURVED
PARTICULARLY BETWEEN 2-5 KM, WITH WEAKER FLOW IN THE LOWEST
KILOMETER. ASSOCIATED SHEAR PROFILES COMBINED WITH UPR-END MODERATE
INSTABILITY (IE. 2000-2500 J/KG), OWING TO THE PRESENCE OF STEEP MID-
LEVEL LAPSE RATES WITHIN THE EML, ATOP A STRONGLY-HEATED (INTO THE
MID/UPR 80S F) AND UNSEASONABLY MOIST BOUNDARY LAYER, WOULD FAVOR
SUPERCELLS WITH LARGE HAIL (SOME SIGNIFICANT >2") AND DAMAGING WIND
GUSTS.
WHILE CONVECTIVE AND ASSOCIATED DEBRIS CLOUDS SHOULD CLEAR THROUGH
MIDNIGHT, A PLUME OF MID/HIGH-LEVEL MOISTURE WILL OVERSPREAD THE
REGION FRI MORNING, WITH LOW TEMPERATURES MOSTLY MID-UPR 60S.
LONG TERM /FRIDAY THROUGH TUESDAY/
AS OF 400 PM WEDNESDAY...
SHORTWAVE RIDGING ALOFT WILL EXTEND NE INTO THE CAROLINAS ON FRIDAY
AFTERNOON AND EVENING, WITH THE AXIS FINALLY PUSHING OFFSHORE ON
FRIDAY NIGHT AS IT GETS STARTS TO GET SUPPRESSED BY THE NEXT DEEP
CLOSED LOW THAT MOVES EAST FROM MN INTO LAKE SUPERIOR AND THE UP OF
MI. A LEE SURFACE TROUGH WILL ALSO BE IN PLACE ACROSS THE SOUTHERN
MID-ATLANTIC. DESPITE MODERATE TO POTENTIALLY EVEN HIGH LEVELS OF
SBCAPE (1500-2500+ J/KG), MODEL SOUNDINGS SHOW WE SHOULD BE FAIRLY
CAPPED AND DRY WITH WNW FLOW IN THE MID AND UPPER LEVELS. THUS
DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO LOOK MOSTLY DRY ON
FRIDAY. A FEW ISOLATED SHOWERS OR STORMS WILL BE POSSIBLE ACROSS THE
FAR N, BUT OVERALL COVERAGE SHOULD BE QUITE LIMITED. IF ANY
CONVECTION IS ABLE TO BREAK THROUGH THE CAP, A STRONG STORM CAN'T BE
RULED OUT AS THERE WILL BE AMPLE MID-LEVEL FLOW WITH BULK SHEAR ON
THE ORDER OF 40-60 KTS. WHILE CENTRAL NC WILL BEGIN EXPERIENCING
SOME WEAK MID-LEVEL HEIGHT FALLS AND FORCING FOR ASCENT ON FRIDAY
NIGHT, WE SHOULD BE STABLE BY THIS POINT WITH LOSS OF DAYTIME
HEATING, SO JUST CONTINUE SLIGHT CHANCE POPS IN THE FAR N AND NW.
HOT TEMPERATURES WILL THE BIGGER CONCERN ON FRIDAY WITH THE RIDGING
ALOFT AND SW LOW-LEVEL FLOW. FORECAST HIGHS ARE IN THE UPPER-80S TO
MID-90S. DEW POINTS IN THE UPPER-60S AND LOWER-70S WILL RESULT IN
HEAT INDICES IN THE MID-90S TO 100 FROM THE TRIANGLE TO THE SOUTH
AND EAST. TEMPERATURES WILL STAY MILD ON FRIDAY NIGHT, WITH LOWS IN
THE UPPER-60S TO MID-70S.
THE MID/UPPER LOW AND OCCLUDED SURFACE LOW WILL TRACK EAST ACROSS
SOUTHERN ONTARIO AND THE UPPER GREAT LAKES ON SATURDAY, DRAGGING A
COLD FRONT TO THE SOUTH THAT GUIDANCE IS IN GOOD AGREEMENT WILL PASS
THROUGH CENTRAL NC ON SATURDAY EVENING/NIGHT. INSTABILITY CONTINUES
TO LOOK MODERATE TO STRONG ALONG WITH 40+ KTS OF MID-LEVEL FLOW
(SIMILAR TO FRIDAY). HOWEVER, MOISTURE WITH THE FRONT DOES NOT LOOK
IMPRESSIVE, AS THE FLOW ALOFT IS STILL FROM A WESTERLY DIRECTION,
AND WE ONLY GET A GLANCING BLOW IN UPPER FORCING WITH THE LOW
TRACKING SO FAR TO OUR NORTH. ENSEMBLE MEAN QPF CONTINUES TO BE LESS
THAN A TENTH OF AN INCH. SO ONLY HAVE SLIGHT TO LOW CHANCE POPS IN
THE AFTERNOON AND EVENING, HIGHEST OVER THE NORTHERN PIEDMONT WHERE
AGAIN THE GREATEST UPPER FORCING WILL BE. STILL CAN'T RULE OUT A FEW
STRONG TO SEVERE STORMS. SATURDAY'S TEMPERATURES MAY BE KEPT DOWN A
BIT BY THE INCREASED PRECIPITATION CHANCES AND APPROACH OF THE COLD
FRONT, PARTICULARLY IN THE NW. BUT THEY SHOULD STILL BE QUITE WARM
WITH HIGHS IN THE MID-80S TO LOWER-90S. HEAT INDICES IN THE UPPER-
90S WILL AGAIN BE POSSIBLE IN THE SE.
OVERALL FORECAST CONFIDENCE DECREASES FOR THE REST OF THE PERIOD.
THE MID-LEVEL FLOW WILL TURN INCREASINGLY NW FROM SUNDAY INTO
TUESDAY, AS WE ARE CAUGHT BETWEEN THE LOW SLOWLY DRIFTING EAST OVER
NEW ENGLAND/SE CANADA AND RIDGING THAT STRENGTHENS AND BUILDS EAST
FROM THE PLAINS TO THE DEEP SOUTH AND TN VALLEY. AT THE SURFACE, A
SECONDARY BACKDOOR COLD FRONT LOOKS TO MOVE THROUGH CENTRAL NC
SOMETIME SUNDAY NIGHT OR MONDAY, AS THE GFS AND ECMWF START TO
DIVERGE ON HOW QUICKLY THE LOW OVER THE CANADIAN MARITIMES MOVES
EAST INTO THE ATLANTIC. THIS FRONT WILL BE QUASI-STATIONARY BUT
SHOULD REMAIN DRAPED TO OUR SOUTH AND WEST THROUGH TUESDAY, KEEPING
US RELATIVELY DRY AND STABLE. THE 12Z GFS AND ECMWF POTENTIAL FOR AN
MCS MOVING THROUGH IN THE NW FLOW ALOFT LATE MONDAY, BUT TIMING AND
PLACEMENT OF THESE SYSTEMS THIS FAR IN ADVANCE IS DIFFICULT TO
PINPOINT. SO ONLY HAVE SLIGHT CHANCE POPS IN THE SOUTH AND WEST FROM
SUNDAY THROUGH TUESDAY. GUIDANCE DEPICTS THE NEXT LOW MOVING NE FROM
THE CENTRAL PLAINS INTO THE UPPER GREAT LAKES ON TUESDAY AND
WEDNESDAY, WHICH MAY HELP PUSH THE BOUNDARY BACK NORTH AS A WARM
FRONT ON WEDNESDAY. BUT THERE IS STILL PLENTY OF DIVERGENCE IN
GUIDANCE ON THE LOW'S STRENGTH. REGARDLESS IT APPEARS SHOWER/STORM
CHANCES WILL INCREASE ON WEDNESDAY, SO HAVE CHANCE POPS RETURNING.
TEMPERATURE FORECAST CONFIDENCE IS LOW FROM SUNDAY ONWARD,
ESPECIALLY BY MIDWEEK, BUT THE OVERALL TREND SEEMS TO BE TRENDING A
BIT COOLER, ESPECIALLY ON THE ECMWF. AS COOL HIGH PRESSURE EXTENDS
SOUTH FROM THE HUDSON BAY INTO THE EASTERN US, EXPECT AT LEAST A
GRADUAL DROP IN TEMPERATURES, WITH HIGHS REACHING CLOSER TO NORMAL.
DEW POINTS SHOULD ALSO BECOME MORE COMFORTABLE, DROPPING INTO THE
50S.
AVIATION /00Z THURSDAY THROUGH MONDAY/
AS OF 800 PM WEDNESDAY...
SCATTERED SHOWERS AND STORMS ARE STILL CAUSING FLIGHT RESTRICTIONS
DUE TO BOTH LOW VISIBILITIES AND CEILINGS THIS EVENING. FLIGHT
RESTRICTIONS SHOULD END AT ALL TAF SITES AROUND OR SHORTLY AFTER
00Z. TONIGHT, ANOTHER ROUND OF SHOWERS IS POSSIBLE, IT LOOKS LIKE
THE BEST CHANCE WILL BE IN THE SOUTH AND POTENTIALLY THE WEST,
HOWEVER CONFIDENCE IS LOW. ANOTHER ROUND OF FOG OR LOW STRATUS IS
EXPECTED TO DEVELOP TONIGHT IN THE NORTH. MVFR RESTRICTIONS ARE THE
MOST LIKELY, HOWEVER AREAS OF DENSE FOG COULD RESULT IN IFR OR LIFR
CONDITIONS. ANY RESTRICTIONS SHOULD IMPROVE BY EARLY TO MID
AFTERNOON. MODELS ARE SHOWING A WIDE RANGE OF SOLUTIONS FOR RAIN
POTENTIAL TOMORROW EVENING, BUT AS OF NOW THE BEST CHANCE FOR
SHOWERS/STORMS LOOKS TO BE IN THE NORTHEAST.
OUTLOOK: CHANCES FOR DIURNAL SCATTERED SHOWERS AND STORMS WILL
CONTINUE THROUGH MUCH OF 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
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ007>011-
021>028-038>043-076>078.
SYNOPSIS...CBL
NEAR TERM...SWIGGETT
SHORT TERM...LUCHETTI/MWS
LONG TERM...DANCO
AVIATION...HELOCK/CBL
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