067
FXUS62 KRAH 221848
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
248 PM EDT TUE APR 22 2025
SYNOPSIS
A SERIES OF MID-LEVEL DISTURBANCES WILL MOVE ACROSS THE SOUTHERN
MIDDLE ATLANTIC AND CAROLINAS THROUGH TONIGHT. MEANWHILE, A BACKDOOR
COLD FRONT WILL APPROACH FROM THE NORTH, THEN MOVE THROUGH THE
CAROLINAS ON WEDNESDAY. THE FRONT WILL STALL AND WEAKEN OVER THE
SAVANNAH BASIN THROUGH THE END OF THE WORK WEEK, WHILE HIGH PRESSURE
WILL OTHERWISE BUILD ACROSS AND OFFSHORE THE MIDDLE ATLANTIC.
NEAR TERM /THROUGH TONIGHT/
AS OF 1240 PM TUESDAY...
A SRN STREAM PERTURBATION, EVIDENT IN WATER VAPOR SATELLITE AND 12Z
UPR AIR DATA FROM NRN MS TO THE E-CNTL GULF COAST, WILL PIVOT SLOWLY
NEWD AND ACROSS THE SOUTH ATLANTIC STATES THROUGH 12Z WED. BETWEEN
THAT TROUGH AND A WEAKENING SUB-TROPICAL HIGH OFF THE FL ATLANTIC
COAST, A RIBBON OF CONVECTIVELY-AMPLIFIED VORTICITY AND TRAIN OF
SMALL MCVS NOW STRETCHING ACROSS THE SRN APPALACHIANS AND TN VALLEY
WILL EDGE EWD AND ACROSS THE CAROLINAS AND SRN MIDDLE ATLANTIC THIS
AFTERNOON-TONIGHT. THE STRONGEST AND MOST INFLUENTIAL FOR CNTL NC
WILL LIKELY EMERGE FROM THE DEEPEST CONVECTIVE CLUSTER NOW EXTENDING
FROM NWRN GA TO NERN AL AND SUBSEQUENTLY OVERSPREAD THE NC PIEDMONT
BETWEEN 22Z-03Z. IT MAY BE PRECEDED BY ANOTHER MCV FROM CONVECTION
THAT MAY DEVELOP AND ORGANIZE BEFOREHAND ALONG A LEE SURFACE TROUGH
AND HINTS OF DEVELOPING AND DEEPENING CONVECTION ACROSS THE SRN NC
PIEDMONT AND UPSTATE OF SC. PRECEDING THE VORTICITY RIBBON, MID-
LEVEL FLOW OVER CNTL NC WILL GENERALLY BE IN THE 30-40 KT RANGE,
LOCALLY MAXIMIZED IMMEDIATELY PRECEDING EACH MCV. THE VORTICITY AXIS
WILL ALSO BE CHARACTERIZED BY SEASONABLY COOL MID-LEVEL
TEMPERATURES, INCLUDING MINUS 13C AT GSO AND RNK AT 12Z, WITH
ASSOCIATED FREEZING LEVELS AROUND 11,000 FT AGL.
AT THE SURFACE, CNTL NC WILL BE SITUATED BETWEEN THE PERSISTENT SUB-
TROPICAL HIGH OFFSHORE, THE AFOREMENTIONED LEE TROUGH EXTENDING
ACROSS THE WRN PIEDMONT OF THE SRN MIDDLE ATLANTIC/CAROLINAS, AND A
SYNOPTIC COLD FRONT ANALYZED AT 16Z FROM WRN NJ SWWD ACROSS N-CNTL
THROUGH SWRN VA, AND ERN TN. THE AFOREMENTIONED DEVELOPING/DEEPENING
CONVECTION ALONG THE LEE TROUGH FROM THE UPSTATE OF SC TO THE SRN
PIEDMONT OF NC, AND IN A ZONE OF DIFFERENTIAL HEATING ALONG THE ERN
PERIPHERY OF A MID-LEVEL CLOUD BAND AND DEEP MOIST AXIS
CHARACTERIZED BY PWS OF 1.25-1.4", WILL PROBABLY RESULT IN MESOSCALE
FRONTOGENESIS AND COLD POOL/OUTFLOW DEVELOPMENT AND EWD PROPAGATION
ACROSS THE SRN/WRN NC PIEDMONT AND WRN SANDHILLS LATE THIS AFTERNOON
AND EVENING, THEN EWD BUT WITH A WEAKENING TEMPERATURE CONTRAST
NOCTURNALLY, THROUGH THE ERN PIEDMONT AND COASTAL PLAIN LATER THIS
EVENING. MEANWHILE, THE SYNOPTIC FRONT WILL MOVE IN BACKDOOR FASHION
SWD THROUGH VA AND INTO NRN AND CNTL NC VERY LATE TONIGHT-WED
MORNING.
TEMPERATURES AHEAD OF THE MID-LEVEL CLOUD BAND AND DEVELOPING
CONVECTION AND SURFACE COLD POOL WILL REACH PERSISTENCE MID TO
PERHAPS UPPER 80S F, RANGING TO MID-UPR 70S WHERE CONVECTION ARRIVES
FIRST OVER THE NW NC PIEDMONT. WHEN COMBINED WITH MIXED SURFACE
DEWPOINTS GENERALLY AROUND 60 F AND THE AFOREMENTIONED SEASONABLY
COOL MID-LEVEL TEMPERATURES, UP TO 750-1500 J/KG OF MLCAPE WILL
RESULT. AND WHEN COMBINED WITH THE 30-40 KNOTS OF MID-LEVEL FLOW,
AND STRONGER WINDS THROUGH THE UPR-LEVELS, EFFECTIVE SHEAR
MAGNITUDES OF 35 TO 45 KNOTS SHOULD BE COMMON AND WILL SUPPORT A MIX
OF MULTICELLS AND PERHAPS TRANSIENT SUPERCELLS CAPABLE OF BOTH
STRONG TO LOCALLY DAMAGING WIND GUSTS AND SOME HAIL. THE GREATEST
STRONG TO SEVERE THREAT SHOULD END BY MID TO LATE EVENING, WITH DEEP
OVERTURNING AND DIABATIC COOLING WITH THE PASSAGE OF THE MCV AND
CONVECTION, AND ALSO NOCTURNAL COOLING. WEAKER CONVECTION MAY
CONTINUE AT TIMES THROUGH THE NIGHT, PARTICULARLY ACROSS SRN NC,
WHERE AN ADDITIONAL MCV MAY TRACK THROUGH A RESIDUALLY, WEAKLY AND
CONDITIONALLY UNSTABLE AIR MASS, AND WITH THE PASSAGE OF THE
SYNOPTIC FRONT. LOW TEMPERATURES WILL LIKELY RANGE FROM UPR 50S TO
AROUND 60 F OVER THE NRN PIEDMONT TO LOW-MID 60S ELSEWHERE.
SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/
AS OF 245 PM TUESDAY...
THE COLD FRONT WILL BE MOVING SOUTHWARD THROUGH THE REGION WEDNESDAY
MORNING BEFORE STALLING TO OUR SOUTH. THROUGHOUT THE DAY, ISOLATED
TO SCATTERED SHOWERS WITH EMBEDDED THUNDERSTORMS ARE POSSIBLE WITH
THE FRONT. PWATS ARE STILL SHOWING VALUES AROUND 1.4-1.5 INCHES
ACROSS THE REGION, THEREFORE AS DIURNAL HEATING INCREASES THROUGHOUT
THE AFTERNOON, CHANCES OF CONVECTION WILL INCREASE. THE GREATEST
CHANCES OF SHOWERS OR STORMS DEVELOPING IS TO THE SOUTH WHERE THE
GREATEST FORCING FROM THE STALLED FRONT WILL BE LOCATED. CAMS ARE
SHOWING VERY LITTLE SHOWER ACTIVITY ACROSS THE REGION, SO KEPT THE
REGION IN SLIGHT CHANCE TO CHANCE POPS, WITH THE GREATEST
PROBABILITIES TO THE SOUTH. THE CHANCE OF ANY SHOWERS BEING
SEVERE IS CURRENTLY LOW AS SHEAR AND INSTABILITY SHOULD BE WEAK.
WITH THE INCREASED CLOUD COVER AND COLD FROPA, HIGH TEMPERATURES
SHOULD BE NEAR TO SLIGHTLY ABOVE NORMAL, OR IN THE MID 70S TO AROUND
80. MINIMUM TEMPERATURES SHOULD BE IN THE MID 50S IN THE NORTHEAST
TO THE LOW 60S IN THE SOUTH.
LONG TERM /THURSDAY THROUGH TUESDAY/
AS OF 245 PM TUESDAY...
* SHOWERS AND POTENTIAL THUNDERSTORMS ARE EXPECTED EVERYDAY THROUGH
THURSDAY
THE COLD FRONT SHOULD STAY STALLED TO OUR SOUTH ON THURSDAY BEFORE
MOVING NORTH THROUGH THE REGION ON FRIDAY AS A WARM FRONT. THE
CHANCE OF SHOWERS WITH THE POTENTIAL OF EMBEDDED THUNDERSTORMS
CONTINUES ON THURSDAY AND FRIDAY WHERE THE FRONTAL BOUNDARY LINES UP
WITH DIURNAL HEATING AND MID-LEVEL PERTURBATIONS IN THE FLOW. THUS,
RAIN AND STORM CHANCES ARE MAXIMIZED IN THE AFTERNOON AND EVENING
EACH DAY. RAIN CHANCES WILL CONTINUE SATURDAY AFTERNOON THROUGH
EVENING, AS ANOTHER COLD FRONT APPROACHES THE REGION FROM THE WEST.
MAXIMUM TEMPERATURES THURSDAY THROUGH SATURDAY SHOULD BE ABOUT 5
DEGREES ABOVE NORMAL ON AVERAGE, WITH HIGHS GENERALLY EXPECTED IN
THE MID 70S TO LOW 80S. THE WARMEST DAY SHOULD BE ON SATURDAY WITH
TEMPERATURES IN THE MID 80S IN THE SOUTH. MINIMUM TEMPERATURES
SHOULD BE ABOUT 10-15 DEGREES ABOVE NORMAL, WITH LOWS IN THE UPPER
50S TO LOW 60S NIGHTLY THROUGH SATURDAY NIGHT.
THE COLD FRONT SHOULD MOVE THROUGH THE REGION EARLY SUNDAY MORNING,
DROPPING HIGH TEMPERATURES INTO THE LOW TO MID 70S SUNDAY AFTERNOON,
WITH LOWS DROPPING INTO THE MID 40S TO LOW 50S. MONDAY AND TUESDAY
SHOULD BOTH WARM AS A SURFACE HIGH BUILDS BEHIND THE FRONT.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AS OF 220 PM TUESDAY...
SCATTERED SHOWERS AND STORMS WITH BRIEF FLIGHT RESTRICTIONS AND
STRONG WIND GUSTS WILL PROVIDE THE BEST CHANCE OF OPERATIONALLY
SIGNIFICANT WEATHER THROUGH MOST OF TONIGHT. A BACKDOOR COLD FRONT
AND FOLLOWING NELY FLOW WILL THEN RESULT IN A GOOD CHANCE OF MVFR
CEILINGS WED MORNING-MIDDAY, TO PERHAPS BRIEFLY IFR ONES IN THE
EARLY MORNING.
OUTLOOK: NELY FLOW BEHIND A BACKDOOR COLD FRONT WILL RESULT IN
PERIODS OF MAINLY MVFR CEILINGS THROUGH FRI, WITH A CHANCE OF IFR
ONES DURING THE MORNING THU AND FRI. THE NELY FLOW WILL ALSO SHIFT
RAIN/THUNDER CHANCES SOUTH TO MAINLY FAY WED-THU, THEN AREA-WIDE
AHEAD OF AND ALONG THE NEXT COLD FRONT FRI-SAT.
CLIMATE
RECORD HIGH MINIMUM TEMPERATURES:
APRIL 22:
KGSO: 63/1967
KRDU: 66/1909
KFAY: 64/1963
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...HELOCK
LONG TERM...HELOCK
AVIATION...MWS
CLIMATE...RAH
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