617
FXUS62 KRAH 170523
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
123 AM EDT THU SEP 17 2026
WHAT HAS CHANGED
* ISOLATED SHOWERS ARE POSSIBLE OVER THE NW PIEDMONT THIS
EVENING. A BETTER CHANCE WILL EXIST AREA-WIDE FRIDAY INTO
SATURDAY AHEAD OF A COLD FRONT.
* THE EXTENDED FORECAST PERIOD COULD BRING MORE SEASONAL
TEMPERATURES WITH UNSETTLED WEATHER EARLY TO MIDDLE OF NEXT
WEEK.
KEY MESSAGES
AS OF 115 AM THURSDAY...
1) A FEW FRONTAL SYSTEMS WILL BRING ISOLATED TO SCATTERED
STORMS THURSDAY THROUGH SAT.
2) AN UNSETTLED PATTERN WITH MORE SEASONAL TEMPERATURES MAY
RETURN EARLY TO MIDDLE OF NEXT WEEK, THOUGH DETAILS ARE UNCLEAR
AT THIS POINT.
DISCUSSION
AS OF 115 AM THURSDAY...
KEY MESSAGE 1... A FEW FRONTAL SYSTEMS WILL BRING ISOLATED TO
SCATTERED STORMS THURSDAY THROUGH SAT.
THE ANOMALOUS UPPER RIDGE OVER THE TN VALLEY IS FORECAST TO
GRADUALLY SHIFT WEST TOWARD THE LOWER MS VALLEY LATE THIS WEEK
AND WEEKEND. AS THAT HAPPENS, NORTHWEST FLOW AROUND THE
PERIPHERY OF THE RIDGE MAY DIRECT A FEW CONVECTIVELY-INDUCED
DISTURBANCES INTO THE REGION TODAY THROUGH EARLY SAT AHEAD OF A
FEW FRONTAL SYSTEMS. MOISTURE LEVELS WILL CORRESPONDINGLY
INCREASE TO WELL ABOVE SEASONAL NORMALS WITH PRECIPITABLE WATER
VALUES AROUND 1.7 TO 2 INCHES DURING THIS PERIOD.
ENSEMBLE AND DETERMINISTIC GUIDANCE SHOWS ISOLATED SHOWERS OR
STORMS DEVELOPING OVER THE LOWER OH VALLEY INTO THE APPALACHIANS
OF NC/VA THIS AFTERNOON AND EVENING IN ASSOCIATION WITH A
CONVECTIVELY- INDUCED DISTURBANCE IN THE DEVELOPING NW FLOW
ALOFT. INSTABILITY TODAY WILL BE CONFINED WEST OF CENTRAL NC IN
VA AND FAR WESTERN NC. ANY SHOWERS THAT DO DEVELOP, ALBEIT
MINIMAL, ARE ONLY EXPECTED TO BRIEFLY IMPACT THE TRIAD AND ALONG
THE VA BORDER OF THE NORTHERN/NORTHWEST PIEDMONT.
A BETTER CHANCE OF SHOWERS AND STORMS WILL EXIST FRIDAY INTO
SATURDAY AS A MORE PROMINENT LEAD TROUGH AND BACKDOOR COLD FRONT
MOVE SOUTH FROM THE NORTHEAST LATE FRIDAY THROUGH EARLY
SATURDAY. INSTABILITY INCREASES TO 1000-1500 J/KG, THOUGH LAPSE
RATES AND SHEAR WILL LIMIT STORM INTENSITY. STORMS WILL MAXIMIZE
DURING THE EARLY TO MID EVENING FRIDAY OVER CENTRAL NC. ON
SATURDAY, AS THE FRONT MOVES THROUGH, THE BEST CHANCE OF STORMS
WILL FOCUS OVER THE SOUTHERN PIEDMONT, SANDHILLS, AND SOUTHERN
COASTAL PLAIN ALONG RESIDUAL INSTABILITY AND ANY LINGERING
CONVERGENCE IF THE FRONT IS SLOW TO MOVE THROUGH. EITHER WAY, NE
FLOW SHOULD FAVOR LOWER TEMPERATURES IN THE MID 80S SATURDAY,
CONTRASTED WITH LOWER 90S FRIDAY. WE CANNOT RULE OUT SOME STRAY
ISOLATED STORMS SUNDAY, BUT THAT PART OF THE FORECAST APPEARS TO
BE TRENDING DRIER.
KEY MESSAGE 2... AN UNSETTLED PATTERN WITH MORE SEASONAL
TEMPERATURES MAY RETURN EARLY TO MIDDLE OF NEXT WEEK, THOUGH
DETAILS ARE UNCLEAR AT THIS POINT.
FROM SUNDAY ONWARD, ENSEMBLE GUIDANCE CONTINUES TO SHOW A
POTENTIALLY UNSETTLED PATTERN, ALBEIT WITH LOW PREDICTABILITY.
REGARDLESS OF WHICH ENSEMBLE CLUSTER SOLUTION YOU EXAMINE, THEY
ALL APPEAR TO AGREE THAT NORTHEAST FLOW WILL RE-EXERT ITSELF
TUESDAY INTO MID-LATE NEXT WEEK AS A 1035-MB HIGH OVER EASTERN
CANADA NOSES DOWN INTO THE MID-ATLANTIC. THIS IS EVIDENT AFTER A
BRIEF WARM AND HUMID PATTERN SUNDAY AND MONDAY IN THE 80S TO
AROUND 90. AHEAD OF THE COOLER AND POTENTIALLY MORE SEASONAL
PATTERN WILL BE A COLD FRONT, SOMETIME MONDAY OR TUESDAY, THAT
COULD BRING SHOWERS/STORMS. COUPLED TO THIS WILL BE A CLOSED
UPPER-LOW OVER THE NE GULF THAT COULD RIDE UP THE SE US IN
RESPONSE TO TROUGHING OVER THE MS/OH VALLEY. IF THAT WERE TO
HAPPEN, SUGGESTED BY SOME ENSEMBLES, AS WELL AS THE EC-AIFS AND
AI-GFS, A SURFACE LOW COULD DEVELOP ALONG A FRONTAL ZONE ALONG
THE CAROLINA COAST, TO FAVOR ISENTROPIC RAIN OR SHOWERS EARLY TO
MIDDLE OF NEXT WEEK. ALL OF THIS IS UNCLEAR GIVEN THE SPREAD IN
THE GUIDANCE, THOUGH THERE ARE SIGNALS FOR MORE SEASONAL
TEMPERATURES IN THE 70S TO LOW 80S IN A CAD-TYPE REGIME IF THAT
WERE TO MATERIALIZE.
AVIATION /05Z THURSDAY THROUGH MONDAY/
AS OF 115 AM THURSDAY...
PREVAILING VFR CONDITIONS ARE EXPECTED THROUGH THE 24 HOUR TAF
PERIOD, EXCEPT FOR LOCALIZED BANKS OF MIST/FOG AFFECTING RWI
WITHIN A PERSISTENCE FORECAST THIS MORNING. SCATTERED SHOWERS
AND ISOLATED STORMS WILL BE POSSIBLE ALONG THE SOUTHERN/MIDDLE
APPALACHIAN MOUNTAINS THIS AFTERNOON. SOME DECAYING SHOWERS MAY
REACH THE TRIAD TERMINALS BEFORE COMPLETELY DISSIPATING
(20-01Z). THE PROBABILITY FOR DEEP CONVECTION TO SUSTAIN ITSELF
AND REACH INT/GSO IS LOW.
OUTLOOK: A BETTER CHANCE OF CONVECTION IMPACTING CENTRAL NC
TERMINALS WILL EXIST ALONG A COLD FRONT FORECAST TO MOVE THROUGH
FRI AFTERNOON-EVENING. A RISK OF CONVECTION WILL LINGER OVER
SRN/SWRN NC FRI NIGHT AND SAT, INCLUDING AT FAY. NELY FLOW
BEHIND THAT FRONT WILL OTHERWISE INCREASE THE LIKELIHOOD OF IFR-
MVFR CEILINGS SAT MORNING, LOWEST AND MOST PROLONGED OVER THE
PIEDMONT (ESPECIALLY AT INT/GSO). ADDITIONAL SUB-VFR CEILINGS
WILL BE POSSIBLE AGAIN SUN MORNING.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...KREN
AVIATION...AS/MWS
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