397
FXUS62 KRAH 271910
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
310 PM EDT THU MAR 27 2025
SYNOPSIS
CANADIAN HIGH PRESSURE OVER THE CAROLINAS WILL DRIFT OFFSHORE
THROUGH TONIGHT. A WARM FRONT WILL LIFT NORTHEAST ACROSS THE MIDDLE
ATLANTIC ON FRIDAY, WITH FOLLOWING BERMUDA HIGH PRESSURE THAT WILL
EXTEND ACROSS THE SOUTH ATLANTIC STATES THROUGH THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 1010 AM THURSDAY...
SOME ADJUSTMENTS HAVE BEEN MADE TO (LOWER) FORECAST SURFACE
DEWPOINTS AND ASSOCIATED RH, WITH THE LATTER LIKELY TO DECREASE INTO
THE MID TEENS TO LOW 20S PERCENT WITH HEATING INTO THE MID-UPR 60S
THIS AFTERNOON. THERE MAY ALSO BE AT LEAST OCCASIONAL GUSTINESS OF
WLY TO WSWLY WINDS INTO THE TEENS KTS.
CANADIAN HIGH PRESSURE AND ASSOCIATED DRY, CONTINENTAL AIR SITUATED
SQUARELY OVER THE NC PIEDMONT THIS MORNING WILL DRIFT ACROSS CNTL
AND ERN NC THROUGH THIS AFTERNOON, THEN OFFSHORE BY THIS EVENING.
THE 12Z-OBSERVED GSO SOUNDING SAMPLED A STRONGER HYDROLAPSE (IE.
DECREASING MOISTURE WITH HEIGHT) AND A DRIER MEAN MIXING RATIO THAN
WED; AND OBSERVED SURFACE DEWPOINTS THIS MORNING HAVE ALREADY BEEN
SEVERAL DEGREES LOWER THAN 24 HOURS AGO - ALL SUGGESTIVE OF SURFACE
DEWPOINTS THAT SHOULD BE LOWER (ON AVERAGE) TODAY THAN ON WED. BOTH
THE GSO AND MHX OBSERVED SOUNDINGS THIS MORNING ALSO SAMPLED 15-20
KTS OF WLY TO NWLY FLOW WITHIN THE FORECAST MIXED/BOUNDARY LAYER
DEPTH OF 7-8 THOUSAND FT AGL, WHICH SUGGESTS OCCASIONAL GUSTS OF
SIMILAR STRENGTH WILL PROBABLY RESULT WITH CONTINUED HEATING AND
MIXING THROUGH THE AFTERNOON. THE HRRR AND RAP TYPICALLY REPRESENT
BOTH SURFACE DEWPOINTS AND SURFACE WINDS/GUSTS WELL AND WERE
CONSEQUENTLY UTILIZED HEAVILY IN THE OFFICIAL GRIDDED FORECAST
UPDATE.
PREV DISCUSSION
/ISSUED 250 AM EDT THU MAR 27 2025/
* INCREASED FIRE DANGER IN EFFECT THROUGH THIS EVENING
NORTHWEST FLOW WILL PERSIST AGAIN FOR MUCH OF TODAY AT MID-LEVELS
WITH TROUGHING OFF THE COAST AND OVER THE NORTHWEST ATLANTIC.
RIDGING OVER THE CENTRAL PLAINS WILL SHIFT INTO THE MID MS VALLEY
TOWARD 12Z SAT. ROUGHLY 1028 MB HIGH PRESSURE WILL BE SITUATED RIGHT
OVERTOP NC TO START OUR DAY. AFTER A COLD START WITH AREAS OF FROST,
HIGHS SHOULD REBOUND NEAR NORMAL INTO THE MID 60S TO AROUND 70,
WARMEST IN THE SW. HIGH PRESSURE WILL GRADUALLY SHIFT OFFSHORE LATER
THIS AFTERNOON AND EVENING, WITH A LIGHT WEST-SOUTHWEST WIND AT 5-10
MPH. AN INCREASED FIRE DANGER WILL BE IN EFFECT THROUGH THIS EVENING
WITH RH LEVELS AROUND 20-24 PERCENT AND CONTINUED DRYNESS AND FIRE
ACTIVITY ACROSS THE CAROLINAS. SOUTHERLY FLOW WILL BE IN FULL SWING
TONIGHT WITH THE HIGH OFF THE COAST. CLOUDS WILL INCREASE TONIGHT,
ESPECIALLY ACROSS THE NORTH AS A WARM FRONT LIFTS INTO THE TN/OH
VALLEY REGION. SOUNDINGS SHOW SATURATION AROUND THE 700-MB LAYER.
THE CONTINUED STIRRING AND CLOUDS WILL FAVOR MUCH WARMER LOWS IN THE
LOW TO MID 40S.
SHORT TERM /FRIDAY AND FRIDAY NIGHT/
AS OF 310 PM THURSDAY...
A MID-LEVEL SUB-TROPICAL HIGH OVER THE NRN GULF WILL DRIFT EWD AND
ACROSS AND OFFSHORE THE SOUTH ATLANTIC STATES, WHILE A SHORTWAVE
TROUGH NOW OVER NWRN MEXICO WILL MIGRATE EWD AND DEAMPLIFY BY THE
TIME IT REACHES THE LWR MS VALLEY SAT MORNING. BETWEEN THE TWO,
INITIALLY THIN CIRROSTRATUS WILL OVERSPREAD CNTL NC FRI AFTERNOON-
EVENING, THEN THICKEN AND LOWER TO AROUND 500 MB OVERNIGHT-SAT
MORNING.
AT THE SURFACE, ~1028 MB HIGH PRESSURE NOW CENTERED OVER SC AND SERN
NC WILL DRIFT EWD AND BECOME CENTERED NEAR BERMUDA FOR THE NEXT FEW
DAYS. A WARM FRONT WILL MEANWHILE RETREAT NEWD ACROSS THE OH VALLEY,
THEN BECOME QUASI-STATIONARY ACROSS THE LWR GREAT LAKES AND NRN
MIDDLE ATLANTIC FRI NIGHT-SAT MORNING. WARM, SLY TO SSWLY FLOW WILL
RESULT ACROSS CNTL NC.
THE PATTERN NOTED ABOVE WILL FAVOR WELL ABOVE AVERAGE TEMPERATURES
(10-20 F) IN THE UPR 70S TO AROUND 80 FRI, ACCOMPANIED BY A SWLY
BREEZE THAT WILL GUST TO 20-25 MPH, FOLLOWED BY MOSTLY MID-UPR 50S
FRI NIGHT. LOW-LEVEL MOISTURE RECOVERY, CHARACTERIZED BY SURFACE
DEWPOINTS IN THE 50S, LIKELY WILL NOT OCCUR IN CNTL NC UNTIL FRI
NIGHT. THAT MOISTENING MAY SUPPORT THE DEVELOPMENT OF AREAS OF
STRATUS EARLY SAT MORNING, IN ADDITION TO THE INCREASING MID/HIGH-
LEVEL MOISTURE NOTED ABOVE.
LONG TERM /SATURDAY THROUGH THURSDAY/
AS OF 239 PM THURSDAY...
UPPER PATTERN THROUGH THE EXTENDED: A WEAK SHORT-WAVE WILL TRAVERSE
THE TN VALLEY SATURDAY BEFORE WASHING OUT OVER THE APPALACHIANS
THROUGH SUNDAY MORNING. A DEEPER TROUGH WILL THEN LIFT ACROSS THE
EASTERN SEABOARD SUNDAY THROUGH TUESDAY. BEYOND TUESDAY, GUIDANCE
DIVERGES, WITH THE ECMWF DEPICTING ENHANCED RIDGING OVER THE EASTERN
US WHILE THE GFS DEPICTS A STRONG MID-WEEK SHORT-WAVE.
SATURDAY THROUGH TUESDAY: THE WESTERN RIDGE OF AN ANCHORED, OFFSHORE
SFC HIGH WILL PROMOTE CONTINUED SLY FLOW ACROSS CENTRAL NC SATURDAY
AND SUNDAY. ON SATURDAY, ANOMALOUS MOISTURE AND ASSOCIATED STRONGER
ISENTROPIC UPGLIDE WILL LARGELY REMAIN WEST OF OUR AREA. AS SUCH,
MOST OF SATURDAY SHOULD REMAIN DRY WITH WARM DAYTIME HIGHS REACHING
THE UPPER 70S TO LOWER 80S.
POPS WILL INCREASE FROM WEST TO EAST LATER SATURDAY NIGHT INTO EARLY
SUNDAY AS THE AFOREMENTIONED WASHED OUT UPPER WAVE AND ASSOCIATED
PERTURBATIONS/MOISTURE MOVES THROUGH OUR AREA. QPF WITH THIS ROUND
SHOULD BE LIMITED (SUNDAY 12Z THROUGH MONDAY 12Z), WITH MEDIAN
ENSEMBLE QPF OF A FEW HUNDREDTHS TO A FEW TENTHS (90TH PERCENTILES
MAX OUT AROUND A HALF INCH). MODELS SHOW AT LEAST A BIT OF
INSTABILITY POSSIBLY DEVELOPING SUNDAY AFTERNOON, BUT FOR NOW, THINK
THUNDER CHANCES SHOULD BE FAIRLY LIMITED SUNDAY. HIGHS ON SUNDAY
WILL REACH THE UPPER 70S.
AFTER A LITTLE LULL SUNDAY EVENING, POPS WILL INCREASE AGAIN FROM
WEST TO EAST EARLY MONDAY AS PRE-FRONTAL SHOWERS/STORMS MOVE ACROSS
OUR AREA. GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE BEST UPPER
FORCING MOVING OVER OUR AREA MONDAY AFTERNOON AND EVENING. AS SUCH,
HAVE TRENDED HIGHEST POPS DURING THIS PERIOD. WHILE THERE REMAINS
SOME UNCERTAINTY WRT TO SEVERE STORM POTENTIAL MONDAY, ENSEMBLES DO
SEEM TO BE TRENDING TOWARDS SHUNTING THE BEST SHEAR/CAPE COMBO TO
OUR SOUTH. WILL HAVE TO KEEP MONITORING AS WE GET CLOSER, BUT THIS
MAY ALSO LIMIT QPF AMOUNTS MONDAY INTO TUESDAY OVER CENTRAL NC AS
WELL.
WEDNESDAY/THURSDAY: AS WAS MENTIONED ABOVE, GUIDANCE SPLITS ON
MIDDLE OF NEXT WEEK WRT TO THE UPPER PATTERN. AS SUCH, DECIDED TO
MAINTAIN LOW POPS IN THIS TIME FRAME FOR NOW. AFTER COOLER EARLY TO
MID WEEK TEMPS IN THE 70S, WE COULD SEE A GOOD WARM UP HEADING INTO
LATER NEXT WEEK.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
AS OF 155 PM THURSDAY...
THE INFLUENCE FROM DRY, CANADIAN HIGH PRESSURE THAT WILL DRIFT OFF
THE COAST OF THE CAROLINAS BY TONIGHT WILL FAVOR CONTINUED VFR
CONDITIONS IN CNTL NC THROUGH FRI. A LITTLE VIRGA MAY ACCOMPANY A
BAND OF MID-LEVEL, 8-11 THOUSAND FT AGL CEILINGS THAT WILL
OVERSPREAD CNTL NC OVERNIGHT-FRI MORNING, BUT WITH NO OPERATIONALLY
SIGNIFICANT IMPACTS AT THE SURFACE.
A MODEST LOW-LEVEL JET AND RELATED STRONG TEMPERATURE INVERSION
TONIGHT WILL ALSO FAVOR MARGINAL LOW-LEVEL WIND SHEAR CONDITIONS
OVERNIGHT-FRI MORNING, ESPECIALLY ALONG THE AXIS OF THE JET NEAR RDU
AND GSO. SWLY SURFACE WINDS WILL THEN STRENGTHEN AND BECOME GUSTY TO
AROUND 20 KTS WITH DAYTIME HEATING BY MID TO LATE MORNING FRIDAY.
OUTLOOK: LOW-LEVEL MOISTURE WILL INCREASE, CHARACTERIZED BY SURFACE
DEWPOINTS IN THE 50S, SUCH THAT AREAS OF IFR STRATUS WILL BE
POSSIBLE BOTH SATURDAY AND SUNDAY MORNING. ADDITIONALLY, A NOCTURNAL
LOW-LEVEL JET COUPLED WITH A MODEST TEMPERATURE INVERSION WILL
PROMOTE A RISK OF MARGINAL LOW-LEVEL WIND SHEAR CONDITIONS THIS
WEEKEND. A CHANCE OF SHOWERS AND STORMS WILL RETURN SUN AND
ESPECIALLY WITH THE PASSAGE OF A COLD FRONT ON MON.
FIRE WEATHER
AS OF 1020 AM THURSDAY...
..INCREASED FIRE DANGER REMAINS IN EFFECT THROUGH THIS EVENING
LOW AFTERNOON RH VALUES IN THE MID TEENS TO LWR 20S PERCENT,
OCCASIONAL WIND GUSTS UP TO 15-20 MPH, AND DRY FUELS WILL YIELD
INCREASED FIRE DANGER TODAY.
ON FRIDAY, DEWPOINTS ARE EXPECTED TO MINIMALLY RISE AND SUPPORT
RECOVERY OF AFTERNOON RH IN THE MID 20S TO MID 30S PERCENT.
ADDITIONALLY, SWLY WINDS WILL STRENGTHEN AND BECOME MORE-FREQUENTLY
GUSTY TO AROUND 20 MPH. WHEN COMBINED WITH WARMER THAN PREVIOUS DAYS
AIR AND FUEL TEMPERATURES, ANOTHER DAY OF INCREASED FIRE DANGER
APPEARS LIKELY, ESPECIALLY OVER THE PIEDMONT AND WRN SANDHILLS.
COORDINATION OF SUCH WILL BE NEEDED WITH SURROUNDING NWS FORECAST
OFFICES AND THE NCFS LATER TODAY.
GRADUALLY RECOVERING RH LEVELS ARE EXPECTED SATURDAY AND ESPECIALLY
SUNDAY INTO EARLY NEXT WEEK, AS A STORM SYSTEM BRINGS POTENTIAL WET
WEATHER AND A REDUCED FIRE DANGER THREAT.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...MWS/KREN
SHORT TERM...MWS
LONG TERM...LUCHETTI
AVIATION...MWS
FIRE WEATHER...MWS/KREN
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