513
FXUS62 KRAH 101025
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
625 AM EDT SAT OCT 10 2026
WHAT HAS CHANGED
* THE THREAT OF SEVERE WEATHER, INCLUDING ISOLATED TORNADOES, HAS
INCREASED ACROSS THE REGION, ESPECIALLY FOR SUNDAY.
KEY MESSAGES
AS OF 304 AM SATURDAY...
1) THE REMNANTS OF ISAIAS WILL BRING PERIODS OF SHOWERS THROUGH
SUNDAY. A THREAT OF SEVERE THUNDERSTORMS CAPABLE OF TORNADOES WILL
ALSO EXIST SUNDAY.
2) MUCH OF NEXT WEEK WILL BE UNSEASONABLY WARM, WITH VERY LITTLE TO
NO CHANCE OF RAIN.
DISCUSSION
AS OF 304 AM SATURDAY...
KEY MESSAGE 1... THE REMNANTS OF ISAIAS WILL BRING PERIODS OF
SHOWERS THROUGH SUNDAY. A THREAT OF SEVERE THUNDERSTORMS CAPABLE OF
TORNADOES WILL ALSO EXIST SUNDAY.
THE REMNANTS OF ISAIAS ARE PRESENTLY LOCATED SOME 50 MILES SOUTH-
SOUTHWEST OF MONTGOMERY AL. OVER THE NEXT 24-36 HOURS, MOST MODEL
AND ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT IN TRACKING THE REMNANTS
OF ISAIAS FROM EAST-CENTRAL AL TODAY INTO THE EASTERN TN VALLEY BY
EARLY SUNDAY. FROM SUNDAY ONWARD, THE EXTRATROPICAL SYSTEM WILL
OCCLUDE AND WEAKEN AS IT TRACKS ENE SOUTH OF NEW ENGLAND BY EARLY
MONDAY.
RAINFALL EXPECTATIONS: THERE HAS NOT BEEN MUCH CHANGE WITH THE
LATEST GUIDANCE WITH RESPECT TO RAINFALL TOTALS. THE LATEST 00Z
HREF/REFS ARE IN RELATIVELY GOOD AGREEMENT ON PRECIPITATION TOTALS,
RANGING FROM 0.75 INCHES TO 2 INCHES. AMOUNTS ARE EXPECTED TO BE
HIGHEST ACROSS THE FAR NW PIEDMONT/TRIAD, WHERE UPSLOPE MAY COMBINE
WITH ISENTROPIC ASCENT, AS WELL AS OVER THE COASTAL PLAIN WHERE
INSTABILITY WILL COME INTO PLAY. A POCKET OF LOWER RAINFALL TOTALS
MAY EXIST OVER THE TRIANGLE AND CENTRAL PORTIONS OF THE AREA, WITH
SOME SPOTS POTENTIALLY SEEING A HALF INCH OR LESS. OF COURSE,
EMBEDDED HIGHER RAINFALL TOTALS ARE POSSIBLE ANYWHERE IN CENTRAL NC,
ESPECIALLY SUNDAY WHEN CONVECTIVE CHANCES GREATLY INCREASE WITHIN
THE VERY MOIST TROPICAL-LIKE AIRMASS. PERIODS OF SHOWERS WILL EXIST
TODAY AND TONIGHT, BUT THERE WILL CERTAINLY BE TIMES OF DRY WEATHER,
ESPECIALLY THE EARLY PART OF THE DAY WHEN DRY AIR WILL EXIST IN THE
LOW-LEVELS.
WIND GUSTS: AN INCREASING PRESSURE GRADIENT WILL DEVELOP TODAY WITH
A RETREATING HIGH TO OUR NORTHEAST AND THE REMNANTS OF ISAIAS MOVING
NORTHEASTWARD. WIND GUSTS OUT OF THE ENE WILL RANGE FROM 25-30 MPH,
WITH INFREQUENT GUSTS UPWARDS OF 35 MPH ACROSS THE WEST AND SOUTHERN
PIEDMONT. THESE GUSTS SHOULD WEAKEN LATER TONIGHT IN THE 15-25 MPH
RANGE AS THE GRADIENT GRADUALLY RELAXES. UNDER A DEVELOPING CAD
WEDGE TODAY, HIGHS WILL RANGE FROM THE LOW/MID 60S NW TO LOW 70S SE.
SEVERE THREAT: PROBABLY THE MOST CONCERNING ASPECT TO THIS WEEKEND
SYSTEM IS THE THREAT OF SEVERE WEATHER. THE LATEST UPDATE FROM SPC
INDICATES A CATEGORY INCREASE IN THE SEVERE WEATHER RISK, ESPECIALLY
FOR SUNDAY. THE MARGINAL RISK HAS EXPANDED FOR LATE TONIGHT AND
EARLY SUNDAY ACROSS THE SOUTHERN PIEDMONT, SANDHILLS, CENTRAL
COASTAL PLAIN, AND FAR SOUTHERN AREAS OF THE TRIANGLE. ON SUNDAY,
THERE IS NOW A SLIGHT RISK IN PLACE FOR ALL BUT THE FAR WESTERN
PIEDMONT OF CENTRAL NC.
BASED ON MODEL FIELDS, IT WOULD APPEAR THE CHANCE OF SEVERE STORMS
WILL BE RATHER LIMITED FOR MOST OF SATURDAY. THE BETTER CHANCE OF
SOME ISOLATED SEVERE STORMS WILL EXIST AFTER MIDNIGHT TONIGHT AND
PRIOR TO DAYBREAK SUN, WHEN LOWER 70S DEWPOINTS SPREAD NORTHWARD
WITHIN AN INCREASINGLY SHEARED ENVIRONMENT. CONFIDENCE IS NOT GREAT
ON COVERAGE FOR THIS EARLY SUNDAY PERIOD GIVEN A LACK OF STORM
COVERAGE SHOWN IN HIGH-RES GUIDANCE.
THE BETTER CHANCE OF SEVERE WEATHER SHOULD BE FROM MID-MORNING
SUNDAY INTO EARLY SUNDAY EVENING. DURING THIS TIME, A SECONDARY LOW
WILL FORM ACROSS THE NW PIEDMONT ALONG THE CAD BOUNDARY/WARM FRONT.
AS THE LOW TRACKS ENE INTO VA DURING THE DAY, LOW TO MID 70S
DEWPOINTS WILL SPREAD OVER MOST OF THE REGION. A SOUTHWESTERLY LOW-
LEVEL JET OF 40-45 KTS WILL BE IN PLACE, ALONG WITH DEWPOINTS IN THE
LOW/MID 70S IN AN INCREASING WARM SECTOR. THE 00Z HREF/REFS INDICATE
A CORRIDOR OF STRONG INSTABILITY OF 1200-1500 J/KG AS A DRY SLOT
STEEPENS LAPSE RATES ACROSS CENTRAL AND EASTERN AREAS OF THE SLIGHT
RISK ZONE. A STRENGTHENING LOW AND DEEP-LAYER SHEAR PROFILE WILL
SUPPORT TRANSIENT SUPERCELLS WITH THE THREAT FOR A BRIEF TORNADO OR
TWO AND DAMAGING WIND GUSTS. THE 00Z HREF/REFS AND HRRR SHOW A
SIGNAL FOR A BROKEN BAND OF CONVECTION MOVING THROUGH THE EARLY
AFTERNOON TO EARLY EVENING ALONG AND EAST OF THE TRIAD. WHILE
UNCERTAINTY REMAINS, THINGS ARE CERTAINLY CONCERNING FOR SUNDAY.
KEY MESSAGE 2... MUCH OF NEXT WEEK WILL BE UNSEASONABLY WARM, WITH
VERY LITTLE TO NO CHANCE OF RAIN.
BROAD MID/UPPER RIDGING OVER THE SOUTHEASTERN US WILL BRING MOSTLY
SUNNY AND DRY WEATHER TO CENTRAL NC FROM MONDAY THROUGH FRIDAY OF
NEXT WEEK. ANY TROUGHING WILL BE CONFINED TO THE WESTERN AND
NORTHEASTERN US. ONE OF THOSE SHORTWAVES (AND ASSOCIATED AREA OF
SURFACE LOW PRESSURE) WILL MOVE ACROSS THE GREAT LAKES AND NEW
ENGLAND ON TUESDAY INTO EARLY WEDNESDAY, DROPPING A BACKDOOR COLD
FRONT SOUTH INTO THE MID-ATLANTIC. THIS FRONT WILL BE MOISTURE-
STARVED SO THERE WILL MOST LIKELY BE NO PRECIPITATION WITH IT, AND
IF THERE IS ANY IT WOULD BE VERY LIGHT, WITH EVEN THE 90TH
PERCENTILE OF ENSEMBLE GUIDANCE LESS THAN A TENTH OF AN INCH. A
NORTHERN STREAM SHORTWAVE WILL DIVE DOWN FROM CANADA LATE IN THE
WEEK AND POTENTIALLY INTERACT WITH THE WESTERN US TROUGH, WHICH
SHOULD EVENTUALLY HELP SUPPRESS THE RIDGE OR SHUNT IT TO OUR EAST
OVER THE WEEKEND. BUT SIGNIFICANT DIFFERENCES STILL EXIST IN THE
GUIDANCE, WITH THE PHASING SOLUTION ON THE GFS RESULTING IN A MUCH
DEEPER AND SLOWER TROUGH COMPARED TO THE ECMWF, SO FORECAST
CONFIDENCE IS LOWER BY THIS TIME.
THERE IS HIGH CONFIDENCE IN ABOVE-NORMAL TEMPERATURES EARLY NEXT
WEEK, WITH HIGHS IN THE UPPER-70S/LOWER-80S AND LOWS IN THE MID-50S
TO 60 ON MONDAY. TUESDAY WILL BE EVEN WARMER, WITH HIGHS IN THE
LOWER-TO-MID-80S (WITHIN A FEW DEGREES OF RECORD HIGHS) AND LOWS IN
THE UPPER-50S TO MID-60S. AFTER THIS, ENSEMBLE SPREAD IN
TEMPERATURES GREATLY INCREASES AS A LOT WILL DEPEND ON THE TIMING OF
THE BACKDOOR COLD FRONT, IF IT EVEN MAKES IT HERE. FOR NOW THE MOST
LIKELY TIMING OF THE PASSAGE IS LATE WEDNESDAY, RESULTING IN
CONTINUED WARMTH ON WEDNESDAY FOLLOWED BY A COOLER THURSDAY AND
POTENTIALLY FRIDAY. HOWEVER, THE GFS LIFTS IT BACK NORTH AS A WARM
FRONT WHICH WOULD BRING TEMPERATURES BACK WELL ABOVE NORMAL ON
FRIDAY.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
AS OF 625 AM SATURDAY...
VFR CONDITIONS ARE EXPECTED TO START THE TAF PERIOD. THE REMNANTS OF
ISAIAS WILL CONTINUE TO MOVE NORTHWARD OVER THE NEXT 24 HOURS,
TRACKING FROM CENTRAL AL INTO THE EASTERN TN VALLEY AND SOUTHERN
APPALACHIANS. RADAR IS PRESENTLY INDICATING POCKETS OF LIGHT RAIN
ACROSS THE AREA, WITH EMBEDDED MODERATE RAIN, THOUGH THERE IS STILL
DRY AIR TO OVERCOME BEFORE SUB-VFR CONDITIONS CAN DEVELOP. THE
CHALLENGE WITH THE FORECAST CONTINUES TO BE THE TIMING OF IFR/MVFR
CONDITIONS. THE LATEST FORECAST MAY STILL BE TOO PESSIMISTIC, BUT
THE LATEST FORECAST DID TREND SLOWER WITH SUB-VFR, WITH ONSET OF
IFR/MVFR IN THE 15-18Z TIMEFRAME. CONDITIONS MAY DETERIORATE FASTER
THAN ANTICIPATED AT GSO/INT WITH UPSLOPE AIDING MODERATE RAIN LATER
THIS MORNING. CONDITIONS MAY BE SLOWER TO DETERIORATE AT RWI AS THIS
TERMINAL WILL BE ON THE EASTERN FRINGE OF THE PRECIPITATION SHIELD
MOST OF THE DAY. OVERALL, EXPECT A GRADUAL LOWERING OF CEILINGS
TONIGHT, IN THE LIFR/IFR RANGE, LOWEST AT GSO/INT. SOME PATCHY FOG
MAY DEVELOP ACROSS THE GSO/INT TERMINALS INTO EARLY SUN BUT
CONFIDENCE ON THIS IS LOW AT THE MOMENT. WIND GUSTS SAT WILL RANGE
FROM 25-30 KT OUT OF THE ENE, WEAKENING AFTER 00Z SUN IN THE 15-20
KT RANGE. A BAND OF ISOLATED STORMS MAY REACH FAY, GSO, AND INT
EARLY SUNDAY, BUT CONFIDENCE WAS TOO LOW TO INCLUDE AT THIS TIME.
THE BETTER CHANCE OF STORMS WILL BE AFTER 12Z SUN. LASTLY, LLWS
CANNOT BE RULED OUT WITH STRONG LOW-LEVEL EASTERLY WINDS AT 35-45
KTS. HOWEVER, THE SIGNAL APPEARS TO SUPPORT MAINLY MECHANICAL
TURBULENCE. WILL LET LATER SHIFTS REEVALUATE THIS THREAT.
OUTLOOK: AREAS OF SHOWERS WITH LIFR/IFR TO SOME MVFR CONDITIONS WILL
CONTINUE MOST OF SUN. A BROKEN LINE OF SHOWERS AND THUNDERSTORMS
WILL BE POSSIBLE FROM LATE MORNING SUN INTO EARLY SUN EVENING. SOME
OF THE STORMS COULD BE SEVERE. A RETURN TO VFR CONDITIONS IS
EXPECTED MON, ALTHOUGH SOME GUSTY NW WINDS WILL EXIST. VFR SHOULD
PREVAIL INTO MIDWEEK.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...KREN/JD
AVIATION...KREN
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