721
FXUS62 KRAH 201934
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
234 PM EST WED NOV 20 2024
SYNOPSIS
A STRONG COLD FRONT WILL CROSS THE AREA THIS EVENING, USHERING IN
COLDER AIR LATER TONIGHT THROUGH LATE WEEK. A SLOW MODERATING TREND
IS EXPECTED OVER THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 1135 AM WEDNESDAY...
FOR THE NEAR TERM UPDATE THIS MORNING, HAVE ADJUSTED POPS FOR
THE PROPAGATION OF A MAIN AREA OF SHOWERS PUSHING EASTWARD ACROSS
THE SOUTHEASTERN HALF OF THE CWA ASSOCIATED WITH A DISTURBANCE
AHEAD OF THE SFC COLD FRONT. THIS FRONT STILL LOOKS TO
POTENTIALLY ENHANCE SOME THINNER SHOWER REGENERATION AS THE
FRONT PASSES MAINLY FROM 00Z-06Z THIS EVENING. SO FAR THE
ACTIVITY LOOKS TO HAVE DROPPED ABOUT 0.25-0.50 INCHES OF GOOD
WETTING RAIN TOTALS. ALSO DID SOME TEMP/DEWPT ADJUSTMENTS PER
RECENT GUIDANCE. PREVIOUS DISCUSSION FOLLOWS...
BAKER
AS OF 321 AM WEDNESDAY...
OVERCAST AND SHOWERY TODAY, TURNING SHARPLY COLDER AND BREEZY
TONIGHT.
THE LATEST RADAR AND DATA ANALYSIS INDICATE SHOWERS INCREASING FROM
NORTH GA NORTHEAST INTO THE WESTERN CAROLINA'S. MOST OF THE RAIN IS
LIGHT WITH A FEW POCKETS OF MODERATE RAINFALL. THESE SHOWERS ARE
ASSOCIATED WITH THE PRE-FRONTAL TROUGH AND UPPER LEVEL DISTURBANCE.
THE LATEST MODELS SUGGEST THAT THE SHOWERS WILL CONTINUE TO MOVE NE
AND AFFECT MUCH OF THE WESTERN AND NORTHERN SECTIONS FIRST THING
THIS MORNING. THE ACTIVITY IS THEN EXPECTED TO FOCUS OVER SOUTHERN
AND EASTERN AREAS LATE MORNING INTO THE AFTERNOON. QPF AROUND 0.1 TO
0.25 IS LIKELY BEFORE 12Z IN THE WEST, WITH AMOUNTS AROUND .1 TO
POSSIBLY 0.25 IN THE SOUTH AND EAST AFTER 12Z. THUS, FAIRLY HIGH POP
WITH LOW QPF. HIGHS IN THE MID TO UPPER 60S, POSSIBLY SOME LOWER 70S
SE BEFORE THE SHOWERS. A LOW OVERCAST OF STRATUS IS EXPECTED TO
PERSIST THROUGH THE AFTERNOON KEEPING TEMPERATURES DOWN A BIT.
THE STRONG COLD FRONT IS EXPECTED TO ARRIVE THIS EVENING, BY AROUND
23Z-01Z IN THE TRIAD, 00Z-02Z OR SO IN THE TRIANGLE, AND AROUND 02Z-
04Z IN THE SE. THERE MAY STILL BE A NARROW BAND OF LOW TOPPED
SHOWERS WITH THE FRONT, FAVORING THE NORTH AND NORTHEAST. WINDS WILL
BECOME WNW AT 15-25 MPH FOR A PERIOD AFTER THE FRONTAL PASSAGE.
GUSTS TO 35 MPH ARE POSSIBLE IN THE TRIAD AND 30 MPH ELSEWHERE.
WINDS WILL WEAKEN A BIT OVERNIGHT TO AROUND 10-15 MPH. THIS STRONG
CAA WILL DRIVE TEMPERATURES INTO THE MID 30S NORTH AND WEST RANGING
INTO THE 40-45 RANGE SE. SKIES WILL BECOME MOSTLY CLEAR TO PARTLY
CLOUDY TONIGHT.
SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/
AS OF 445 AM WEDNESDAY...
WE WILL NOT GO WITH A FREEZE WATCH YET. WE WILL LET THE DAY SHIFT
ANALYZE THE NEW DATA BEFORE TRYING TO PIN DOWN THE EXACT LOCATIONS.
STRONG CAA WILL CONTINUE THURSDAY. IN ADDITION, CLOUDINESS WILL
INCREASE AGAIN DURING THE LATE MORNING AND AFTERNOON AS THE SURFACE
HEATS AND THE MID/UPPER LEVELS CONTINUE TO COOL WITH THE LOWERING
HEIGHTS ALOFT. WEST WINDS WILL BECOME WINDY AFTER MIXING BEINGS
AROUND MID-MORNING. EXPECT 15-25 MPH WITH GUSTS TO 30 MPH. HIGHS
WILL LIKELY RANGE FROM AROUND 50 NW TO NEAR 60 SE.
WE ARE A BIT HESITANT IN ISSUING A FREEZE WATCH AT THIS TIME. THERE
ARE MIXED SIGNALS FOR THE POTENTIAL FOR FREEZING CONDITIONS THURSDAY
NIGHT. SOME CLOUDINESS IS EXPECTED TO CONTINUE WITH THE NW FLOW AND
COLD AIR ALOFT. LOWS WILL DEPEND ON HOW MUCH CLOUDINESS CONTINUES.
IN ADDITION, SOME MIXING WILL CONTINUE WITH A LIGHT WEST WIND. THIS
WILL LIKELY PLAY A ROLE IN LOW TEMPERATURES, ESPECIALLY CLOSER TO
THE MOUNTAINS AROUND THE NW PIEDMONT TRIAD. EXPECT LOWER TO MID 30S
FOR LOWS WITH VARIABLY CLOUDY SKIES. IF THE SKIES ARE EXPECTED TO
CLEAR FOR A SUBSTANTIAL TIME IN LATER FORECASTS, A FREEZE WARNING OR
FROST ADVISORY WILL BE NEEDED.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
AS OF 230 PM WEDNESDAY...
* BRISK FRI MORNING WITH WIND CHILLS IN THE LOW 30S TO UPPER 20S
FROM 2 AM THROUGH 9 AM.
* PATCHY FROST POSSIBLE SAT AND SUN MORNING WITH MODERATING
TEMPERATURES THROUGH EARLY NEXT WEEK.
AN UNSEASONABLY DEEP MID/UPPER LEVEL CLOSED LOW WILL BE POSITIONED
OVER THE NORTHERN MID-ATLANTIC BY FRI MORNING. AN OCCLUDED SURFACE
LOW WILL WOBBLE OVER THE NORTHERN MID-ATLANTIC THROUGH FRI AND
PROVIDE A STRONG PRESSURE GRADIENT OVER THE AREA AS THE SURFACE LOW
DEEPENS TO AROUND 990MB. THIS SHOULD PROMPT A BRISK SURFACE WIND
THROUGH MUCH OF THE DAY ON FRI. TEMPERATURES WILL STRUGGLE TO GET
OUT OF THE UPPER 40S ACROSS THE NORTH AND LOW 50S ACROSS THE SOUTH
AS WINDS INCREASE TO AROUND 15 MPH WITH GUSTS 20 TO 30 MPH, ALTHOUGH
INFREQUENT GUSTS UP TO 35 MPH CAN'T BE RULED OUT. SIMILAR WIND GUSTS
ARE EXPECTED SAT AS WELL AS THE SURFACE LOW SLOWLY SHIFTS INTO THE
NORTHEAST THROUGH THE AFTERNOON. THERE IS SOME UNCERTAINTY ON IF
THESE GUSTS WILL CONTINUE OVERNIGHT. POINT SOUNDINGS FROM THE 12Z
GFS SHOW A CONTINUED MIXED LAYER OVERNIGHT FRI NIGHT INTO SAT WHEN
SOME GUSTINESS MY CONTINUE, BUT THE 12Z NAM ESTABLISHES A WEAK
STABLE LAYER AT THE SURFACE AND PREVENTS THE STRONGER GUSTS FROM
REACHING THE SURFACE.
WITH THE GRADUALLY MODIFYING CANADIAN AIRMASS IN PLACE BY FRI
MORNING, OVERNIGHT LOWS WILL SOLIDLY BE IN THE 30S EACH NIGHT, BUT
CONFIDENCE IS LOW IF THEY WILL REACH FROST/FREEZE CRITERIA. STIRRING
OVERNIGHT FRI NIGHT INTO SAT SHOULD PREVENT RADIATIONAL COOLING WITH
POCKETS FALLING BELOW 36 DEGREES IN THE OUTLYING AREAS OF THE
PIEDMONT. SAT NIGHT INTO SUN MORNING HAS A BETTER CHANCE TO FALL
BELOW 36 DEGREES AS THE PRESSURE GRADIENT BEGINS TO RELAX AND A
SHALLOW INVERSION IS ABLE TO DEVELOP AND DEEPEN. COLDEST
TEMPERATURES WILL LIKELY BE ACROSS THE SOUTHWEST QUADRANT OF THE
FORECAST AREA WHERE CALM CONDITIONS ARE EXPECTED WITH CLEAR SKIES.
TEMPERATURES WILL SLOWLY MODERATE THROUGH NEXT WEEK AS THE SURFACE
HIGH SHIFTS OUT OVER THE WESTERN ATLANTIC BY MON AND RETURNS A
SOUTHWEST LOW-LEVEL FLOW TO THE REGION. A LOW AMPLITUDE SYSTEM AND
WEAK SURFACE REFLECTION IS FORECAST TO PASS THROUGH THE GREAT LAKES
AND INTO ONTARIO LATE MON INTO TUES, BUT ONLY AN INCREASE IN CLOUDS
AND A DRY COLD FRONTAL PASSAGE IS EXPECTED FOR OUR AREA.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
AS OF 1245 PM WEDNESDAY...
TAF PERIOD: AN AREA OF RAIN HAS MOVED THROUGH MUCH OF THE REGION,
WITH IFR/LIFR CONDITIONS AT ALL SITES. AN ANOTHER AREA OF RAIN COULD
FILL BACK INTO THE AREA DURING THE LATE AFTERNOON AND EVENING HOURS.
A COLD FRONT WILL MOVE THROUGH DURING THE EVENING, BRINGING DRIER
AIR (MIXING OUT THE LOW CEILINGS) AS WELL AS GUSTY WINDS. HAVE GONE
WITH 25-30 KT WINDS IN THE TAFS, BUT SOME MODEL GUIDANCE IS
INDICATING THAT GUSTS ALONG THE FRONT COULD BE IN THE 30-40 KT
RANGE, AND THIS WILL REQUIRE FURTHER INVESTIGATION. AFTER A 3-6 HR
WINDOW, IT APPEARS THAT ALL SITES SHOULD HAVE GUSTS COME TO AN END
DURING THE OVERNIGHT PERIOD WITH CLEARING SKIES. AFTER SUNRISE,
DAYTIME MIXING SHOULD ALLOW FOR ANOTHER ROUND OF GUSTS, ALTHOUGH
THURSDAY'S GUSTS SHOULD NOT BE NEARLY AS STRONG AS THE OVERNIGHT
WINDS, CLOSER TO 20 KT WIND. SOME HIGHER CLOUDS WILL LIKELY MOVE
INTO THE TRIAD LATE THURSDAY MORNING, ALTHOUGH THESE WILL NOT BRING
ANY FLIGHT RESTRICTIONS.
OUTLOOK: NO PRECIPITATION IS IN THE FORECAST DURING THE OUTLOOK
PERIOD WITH VFR CONDITIONS. FRIDAY AND SATURDAY WILL HAVE GUSTS TO
25 KT.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BADGETT
NEAR TERM...BADGETT/BAKER
SHORT TERM...BADGETT
LONG TERM...SWIGGETT
AVIATION...GREEN
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