698
FXUS62 KRAH 011322
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
920 AM EDT TUE APR 1 2025
SYNOPSIS
A COLD FRONT WILL MOVE SOUTHEAST AND OFF THE COAST OF THE CAROLINAS
TODAY. HIGH PRESSURE WILL FOLLOW AND BUILD ACROSS AND OFFSHORE THE
MIDDLE ATLANTIC THROUGH WEDNESDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 920 AM TUESDAY...
THE MORNING UPDATE PRIMARILY INCLUDED TWEAKS TO HOURLY TEMPERATURES
AND DEWPOINTS. THE COLD FRONT HAS JUST MOVED SOUTHEAST OF THE
FORECAST AREA, WITH DEWPOINTS IN CLINTON DROPPING 10 DEGREES IN THE
LAST TWO HOURS. SOME CLOUD COVER IS LIKELY TO REMAIN IN THE FORECAST
AREA THROUGHOUT THE DAY. PREVIOUS DISCUSSION FOLLOWS.
AS OF 330 AM TUESDAY...
BEHIND A SHORTWAVE PERTURBATION THAT WILL MOVE OFF THE MIDDLE
ATLANTIC COAST THIS MORNING, RIDGING AND RISING HEIGHTS WILL EXPAND
ACROSS THE MIDDLE ATLANTIC AND SOUTHEAST. UNDERLYING SURFACE HIGH
PRESSURE WILL STRENGTHEN WHILE BUILDING FROM THE OH VALLEY TO THE
MIDDLE ATLANTIC COAST. VEERING SURFACE WINDS AROUND THE HIGH, FROM
NWLY THIS MORNING TO NELY THIS AFTERNOON, WILL FAVOR COOLER AND MORE
SEASONABLE TEMPERATURES THAN RECENT DAYS AND HIGH TEMPERATURES IN
THE MID 60S TO LWR 70S.
ONSHORE LOW-LEVEL FLOW, AND VEERING WIND PROFILES WITH HEIGHT/WAA
BELOW A PROMINENT, ~850 MB SUBSIDENCE INVERSION, WILL LIKELY RESULT
IN THE DEVELOPMENT AND EXPANSION OF AN AREA OF STRATOCUMULUS CEILINGS
ACROSS THE SANDHILLS SHORTLY AFTER MIDNIGHT, THEN NWWD ACROSS THE
SRN AND WRN PIEDMONT THROUGH WED MORNING. LOW TEMPERATURES IN THE
40S, TO LWR 50S ACROSS THE SRN SANDHILLS AND SRN PIEDMONT, WILL BE
TEMPERED BY BOTH ELY SURFACE STIRRING AND THE DEVELOPING/EXPANDING
CLOUD LAYER.
SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/
AS OF 400 AM TUESDAY...
A SUB-TROPICAL MID-LEVEL HIGH WILL STRENGTHEN OVER THE SWRN N.
ATLANTIC, WITH STANDARDIZED 850-500 MB HEIGHT ANOMALIES OF 2-3 SIGMA
FORECAST BY 12Z THU. AT THE SURFACE, HIGH PRESSURE INITIALLY ALONG
THE MIDDLE ATLANTIC COAST WILL MOVE OFFSHORE AND DIRECT A WARMING
AND MOISTENING SELY TO SLY FLOW THROUGHOUT THE SOUTH ATLANTIC AND
CAROLINAS. THAT WARMING WILL LIKELY NOT BE FULLY REALIZED UNTIL
LATER IN THE WEEK, HOWEVER, OWING TO CLOUDY OR MOSTLY SO CONDITIONS
COURTESY OF STRENGTHENING WAA AND DEEPENING SATURATION TRAPPED BELOW
THE SUBSIDENCE INVERSION. THE WAA WILL BE STRONGEST AND SATURATED
LAYER DEEPEST AND LOWEST FROM THE NW PIEDMONT WWD INTO THE
MOUNTAINS, WHERE AREAS OF LIGHT RAIN AND DRIZZLE WILL RESULT AND
CONTRIBUTE TO THE DEVELOPMENT OF IN-SITU COLD AIR DAMMING. HIGH
TEMPERATURES OVER THE FAR NW PIEDMONT MAY CONSEQUENTLY STRUGGLE TO
REACH 60 F WED, WITH TEMPERATURES OTHERWISE LIKELY TO RANGE THROUGH
THE 60S, TO LWR 70S IN THE COASTAL PLAIN, SRN SANDHILLS, AND SRN
PIEDMONT.
STEADY MOISTURE ADVECTION, CHARACTERIZED BY SURFACE DEWPOINTS
INCREASING INTO THE 60S BY THU MORNING, WILL CONTRIBUTE TO THE
DEVELOPMENT OF WIDESPREAD LOW OVERCAST, AND AREAS OF LIGHT RAIN AND
DRIZZLE, WED NIGHT. LOW TEMPERATURES WILL BE COMPARABLE TO THE
AFOREMENTIONED SURFACE DEWPOINT VALUES, GENERALLY LWR-MID 60S AND
ABOUT 20F ABOVE AVERAGE.
LONG TERM /THURSDAY THROUGH MONDAY/
AS OF 430 AM TUESDAY...
THE FIRST PART OF THE EXTENDED PERIOD (THURSDAY THROUGH SATURDAY)
WILL LARGELY BE DOMINATED BY A SUBTROPICAL HIGH ALOFT THAT REMAINS
ANCHORED EAST OF FL, WHILE A WESTERN ATLANTIC SURFACE HIGH DRIFTS
SOUTH FROM EAST OF NOVA SCOTIA TO BECOME CENTERED EAST OF GA/FL BY
SATURDAY. THIS HIGH WILL ACT TO STALL OUT A COLD FRONT WHICH WILL
REMAIN OVER THE OH AND TN VALLEYS. SW FLOW ALOFT WILL BRING A GOOD
AMOUNT OF CLOUD COVER AND PW VALUES TO 150-200% OF NORMAL THROUGH
SATURDAY, WHILE S/SW LOW-LEVEL FLOW WILL BRING PLENTY OF WARM, MOIST
AIR WITH SURFACE DEW POINTS IN THE 60S AND A CHANCE FOR LOW STRATUS
EACH MORNING. SBCAPE IN MODEL GUIDANCE IS IN THE 500-1500 J/KG RANGE
EACH DAY. SO CAN'T RULE OUT SOME ISOLATED CONVECTION ON THURSDAY
MAINLY IN THE NW IF THE FRONT CAN GET CLOSE ENOUGH, AND AGAIN ACROSS
THE N ON FRIDAY AFTERNOON AND EVENING AS A SHORTWAVE AND ASSOCIATED
SURFACE LOW OVER SE CANADA TRY TO PUSH A BACKDOOR FRONT SOUTH INTO
VA. HOWEVER, CURRENT GUIDANCE KEEPS THE FRONT TO OUR NORTH, AND THE
HIGH TO OUR SE SHOULD HELP SUPPRESS PRECIPITATION DEVELOPMENT.
FURTHERMORE, GFS/ECM/CMC ENSEMBLE MEAN QPF ARE ONLY A FEW HUNDREDTHS
TO A TENTH OF AN INCH AT MOST BOTH DAYS. SO ONLY CARRY SLIGHT TO LOW
CHANCE POPS. SATURDAY/SATURDAY NIGHT LOOK DRY AS A SOUTHERN STREAM
WAVE OVER THE SOUTHERN PLAINS ACTS TO PUSH THE FRONTAL ZONE EVEN
FARTHER WEST, WHILE THE BACKDOOR FRONT LIFTS WELL TO OUR NORTH.
BETTER RAIN CHANCES COME ON SUNDAY AND SUNDAY NIGHT AS THE HIGH
FINALLY STARTS TO BREAK DOWN AND SHIFT EAST, IN RESPONSE TO THE
SOUTHERN STREAM WAVE AND A BROAD NORTHERN STREAM TROUGH OVER THE
UPPER GREAT LAKES. THIS WILL HELP PUSH THE COLD FRONT EAST THROUGH
OUR REGION, BUT HOW QUICKLY IT IS ABLE TO MOVE THROUGH WILL DEPEND
ON THE DEGREE OF PHASING THAT OCCURS BETWEEN THE TWO WAVES. GUIDANCE
HAS OVERALL BEEN TRENDING SLOWER WITH THE FRONT, NOT BRINGING IT
THROUGH UNTIL SUNDAY NIGHT (ON THE ECMWF) OR MONDAY (ON THE GFS).
SOME STORMS CAN'T BE RULED OUT WITH THE FRONT AS THERE LOOKS TO BE
AT LEAST SOME INSTABILITY AROUND, BUT THIS WILL DEPEND ON WHETHER IT
CAN LINK UP WITH DIURNAL HEATING. PRECIPITATION MAY LINGER INTO
MONDAY ESPECIALLY SE IF THE FRONTAL PASSAGE IS SLOW ENOUGH, SO
CONTINUE SOME LOW-END POPS INTO MONDAY.
TEMPERATURES WILL BE QUITE WARM DURING THE PERIOD, AS HIGHS INCREASE
TO 80S ON THURSDAY AND UPPER-80S TO LOWER-90S ON FRIDAY AND
SATURDAY. LOWS SHOULD MAINLY BE IN THE 60S. THE FORECAST ON FRIDAY
AND SATURDAY IS CLOSE TO RECORD HIGHS FOR APRIL 4 AND 5 AT GSO, RDU
AND FAY. IT WILL NOT BE A "DRY HEAT" EITHER AS DEW POINTS WILL
LARGELY BE IN THE 60S. SUNDAY AND MONDAY'S TEMPERATURES ARE LOWER
CONFIDENCE AS THEY WILL DEPEND ON HOW QUICKLY THE FRONT IS ABLE TO
GET HERE. THE CURRENT FORECAST HAS HIGHS IN THE 80S ON SUNDAY AND
UPPER-60S TO MID-70S ON MONDAY. ONE BENEFIT OF THE HIGHER DEW POINTS
IS THEY SHOULD KEEP RH'S WELL ABOVE LEVELS THAT WOULD AGGRAVATE FIRE
WEATHER CONCERNS.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
AS OF 750 AM TUESDAY...
BEHIND A COLD FRONT PASSING SLOWLY THROUGH SERN NC, NWLY SURFACE
WINDS MAY BRIEFLY GUST NEAR 20 KTS THIS MORNING, ESPECIALLY AT FAY,
RWI, AND RDU. WINDS WILL THEN WEAKEN THIS AFTERNOON AND GRADUALLY
VEER TO ELY TONIGHT. THAT ELY FLOW WILL DIRECT LOW-LEVEL MOISTURE
ONSHORE AND RESULT IN THE LIKELY DEVELOPMENT AND EXPANSION OF AN
AREA OF MVFR CEILINGS NEAR FAY AROUND 06Z, THEN NWWD ACROSS THE
PIEDMONT, PARTICULARLY AT INT AND GSO, THROUGH 12Z WED.
OUTLOOK: MVFR CEILINGS ARE LIKELY TO LINGER OVER THE PIEDMONT
(ESPECIALLY INT/GSO) THROUGH WED, FOLLOWED BY THE DEVELOPMENT OF
WIDESPREAD IFR CEILINGS AND AREAS OF LIGHT RAIN AND DRIZZLE WED
NIGHT. ANOTHER ROUND OF IFR CONDITIONS WILL PROBABLY OCCUR AGAIN THU
NIGHT, AMID INCREASINGLY MOIST/HUMID LOW-LEVEL FLOW.
CLIMATE
RECORD HIGH TEMPERATURES:
APRIL 3:
KRDU: 91/1967
KFAY: 90/1934
APRIL 4:
KGSO: 86/1934
KRDU: 88/1934
KFAY: 93/1910
APRIL 5:
KGSO: 87/1942
KRDU: 90/1942
KFAY: 91/1942
APRIL 6:
KFAY: 91/2010
RECORD HIGH MINIMUM TEMPERATURES:
APRIL 3:
KGSO: 64/1946
KRDU: 62/2000
KFAY: 65/1977
APRIL 4:
KGSO: 62/1999
KRDU: 63/2017
KFAY: 63/2017
APRIL 5:
KGSO: 60/2023
KRDU: 64/1910
KFAY: 64/2008
APRIL 6:
KGSO: 65/2023
KFAY: 69/2023
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...GREEN/MWS
SHORT TERM...MWS
LONG TERM...DANCO
AVIATION...MWS
CLIMATE...NWS
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