373
FXUS62 KRAH 191801
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
101 PM EST THU DEC 19 2024
SYNOPSIS
AN ARCTIC COLD FRONT AND STRONG UPPER LEVEL DISTURBANCE WILL
APPROACH FROM THE WEST LATE TONIGHT AND CROSS THE AREA FRIDAY
THROUGH EARLY FRIDAY NIGHT. THIS WILL BRING MUCH COLDER AIR INTO THE
REGION FOR THE WEEKEND.
NEAR TERM /TODAY THROUGH TONIGHT/
AS OF 1027 AM THURSDAY...
NELY SFC FLOW IS FIRMLY IN PLACE THIS MORNING BEHIND A BACKDOOR COLD
FRONT WHICH HAS CLEARED SOUTHEAST OF OUR AREA. THE 12Z KGSO SOUNDING
INDICATED A FAIRLY STABLE BOUNDARY LAYER, WITH LINGERING MOISTURE
THROUGH ABOUT 850 MB. FORECAST SOUNDINGS INDICATE A CONTINUATION OF
LOCKED IN LOW-LEVEL MOISTURE THROUGH THE OVERNIGHT HOURS. THIS
SHOULD KEEP A STEADY DECK OF STRATUS FOR MUCH OF THE AREA THROUGH
THE PERIOD. HIGHS TODAY WILL STRUGGLE TO REACH THE LOWER TO MID
50S.
AS WE PIVOT TO TONIGHT, A STRONG VORT MAX WILL APPROACH THE TN
VALLEY. GIVEN THE LOCKED IN LOW-LEVEL MOISTURE EXPECTED OVERNIGHT,
SOME ENERGY OUT AHEAD OF THIS FEATURE MAY PROVIDE ENOUGH LIFT TO
PRODUCE POCKETS OF DRIZZLE AND/OR LIGHT RAIN. BEST CHANCES SEEM TO
BE ALONG AND EAST OF US-1, STARTING NEAR ~07Z AND PERSISTING THROUGH
THE END OF THIS PERIOD. SFC OBSERVATIONS SHOULD MOSTLY REPORT TRACE
TO MAYBE A FEW HUNDREDS OF AN INCH OUT ACROSS THE COASTAL PLAIN.
OVERNIGHT LOWS IN THE MID TO UPPER 30S IS EXPECTED.
SHORT TERM /FRIDAY AND FRIDAY NIGHT/
AS OF 245 AM THURSDAY...
PASSAGE OF A POTENT UPPER PV MAX AND ARCTIC SURFACE FRONT FRI WILL
BRING A CHANCE OF SHOWERS FRI AND DRAW MARKEDLY COLDER AIR INTO THE
REGION STARTING FRI NIGHT.
A STRONG SHORTWAVE TROUGH NOW DIVING THROUGH THE DAKOTAS WILL TRACK
SE THROUGH THE MIDWEST TODAY AND, AS A SERIES OF SHEARED VORTICITY
LOBES STREAK THROUGH ITS BASE, WILL MOVE THROUGH NC FRI AFTN AND
EVENING, ACCOMPANIED BY AN ARCTIC SURFACE COLD FRONT. INCREASING LOW
LEVEL WSW AND W FLOW FRI MORNING SHOULD HELP SCOUR OUT THE STRATOCU
OVER THE AREA FROM SW TO NE, RESULTING IN A PERIOD OF FAIR SKIES,
ALTHOUGH THIS WILL QUICKLY GIVE WAY TO INCREASING CLOUDS ONCE AGAIN.
MODELS CONTINUE TO INDICATE A PRONOUNCED TROPOPAUSE FOLD WITH THE 2
PVU SURFACE EXTENDING BELOW 600 MB, RESULTING IN A STEEPENING OF
LAPSE RATES AND MOISTENING OF THE COLUMN THROUGH THE LOWEST 10K-
12KFT. AS SUCH, SCATTERED SHOWERS ARE STILL EXPECTED FRI INTO EARLY
FRI NIGHT. WHILE THE PROJECTED ELEVATED/SHALLOW CAPE IS QUITE SMALL,
GIVEN THE STRONG PV MAX AND THE ANTICIPATED MOISTENING UP INTO THE
MIXED PHASE REGION ALOFT, A FEW LIGHTNING STRIKES ARE POSSIBLE. THE
ARCTIC FRONT WILL PUSH ESE AND OFFSHORE FRI NIGHT, RESULTING IN
CLEARING W TO E OVERNIGHT, AND A BRIEF PERIOD OF GUSTY WINDS IS
POSSIBLE. EXPECT HIGHS IN THE UPPER 40S TO MID 50S, FOLLOWED BY LOWS
FROM THE UPPER 20S TO MID 30S. -GIH
LONG TERM /SATURDAY THROUGH WEDNESDAY/
AS OF 205 AM THURSDAY...
WELL BELOW NORMAL TEMPERATURES ARE EXPECTED INTO EARLY NEXT WEEK.
THEREAFTER, A MODERATING TREND IS EXPECTED WITH A SLIGHT UPTICK IN
RAIN CHANCES BY MIDWEEK.
NORTHWEST FLOW ALOFT WILL BE IN PLACE SAT AND SUN. AT THE SURFACE,
AN ANOMALOUSLY STRONG 1040 MB ARCTIC HIGH OVER THE UPPER MS VALLEY
AND GREAT LAKES REGION SAT INTO SUN WILL GRADUALLY SETTLE INTO THE
MID-ATLANTIC REGION BY MON. WHILE CHILLIER AIR WILL ARRIVE SAT
BEHIND THE DEPARTING SYSTEM FRI NIGHT, ARCTIC AIR WILL NOT FILTER IN
UNTIL SAT NIGHT AND SUN MORNING, WHEN THE HIGH BUILDS INTO THE LOWER
GREAT LAKES. AS A RESULT, WE ARE BELOW AVERAGE BY ABOUT 5-8 DEGREES
IN THE MID 40S TO NEAR 50. AS THE ARCTIC AIR BUILDS INTO THE REGION
SAT NIGHT, WE SHOULD SEE LOW DIP SOME 9-12 DEGREES BELOW AVERAGE IN
THE UPPER TEENS TO LOW 20S. A FAST-MOVING SHORTWAVE WILL AGAIN MOVE
OVERHEAD SAT NIGHT AND COULD PRODUCE SOME OROGRAPHIC CIRRUS. THE GFS
ACTUALLY SHOWS SOME DECENT HIGH-LEVEL MOISTURE VIA FORECAST
SOUNDINGS, WHICH COULD LIMIT RADIATIONAL COOLING SOMEWHAT.
THE ARCTIC AIR WILL BE WELL ENTRENCHED SUN AND MON, WITH HIGHS SOME
12-18 DEGREES BELOW IN THE UPPER 30S TO LOW 40S, COLDEST ON SUN.
EXCELLENT RADIATIONAL COOLING SUN NIGHT WITH THE SURFACE HIGH TO OUR
NORTH WILL MAKE FOR OUR COLDEST NIGHT IN THE MID TEENS TO LOW 20S.
AS WE HEAD INTO THE EARLY TO MIDDLE OF NEXT WEEK, RIDGING WILL BUILD
ALOFT MON AND TRANSITION TO QUASI-ZONAL FLOW COME TUE. IT LOOKS LIKE
WE WILL BE IN A SPLIT FLOW, WITH THE NORTHERN JET STREAM OVER THE
GREAT LAKES AND THE SUBTROPICAL JET OVER THE GULF. A SYSTEM WILL
SKIRT TO OUR NORTH MON AND TUE. ENSEMBLES THEN SHOW A POTENTIAL
SHORTWAVE IN THE PERTURBED FLOW PERHAPS REACHING OUR AREA COME
CHRISTMAS DAY. ALTHOUGH PW'S INCREASE TO THE 75TH PERCENTILE FOR
LATE DECEMBER, SOLUTIONS VARY ON THE HOW THE SYSTEM EVOLVES AS IT
TRACKS EASTWARD, AS WELL AS THE DEGREE OF RIDGING OFF THE SE COAST.
AS A RESULT, CONFIDENCE IS LOW ON SPECIFICS SO KEPT RAIN CHANCES IN
THE 20-30 PERCENT RANGE. EITHER WAY, THE AIRMASS IS WELL ABOVE
FREEZING SO ANY PRECIPITATION THAT DOES FALL WOULD BE ALL LIQUID.
HIGHS MON-WED SHOULD SEE A WARMING TREND FROM THE UPPER 40S TO LOW
50S TUE TO THE LOW TO UPPER 50S ON CHRISTMAS.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
AS OF 1250 PM THURSDAY...
A FEW MVFR CEILINGS ARE HANGING ON THIS AFTERNOON, BUT GENERALLY
THINK ALL TERMINALS SHOULD LIFT TO VFR THROUGH THIS EVENING (SANS
KFAY WHICH MAY STAY LOCKED IN). THE LOWER LEVELS ARE STILL EXPECTED
TO REMAIN SATURATED TONIGHT, AS ALL SITES ARE EXPECTED TO SOCK BACK
IN WITH LIKELY MVFR STRATUS. PATCHY DRIZZLE/LIGHT RAIN MAY BE
POSSIBLE AT KFAY/KRWI BETWEEN ~07 TO 15Z. ADDITIONAL SCATTERED
LIGHT RAIN/SHOWERS LOOK POSSIBLE FRIDAY AFTERNOON AS AN ARCTIC COLD
FRONT PUSHES THROUGH. ANY LINGERING GUSTS THIS AFTERNOON SHOULD
SUBSIDE TONIGHT.
LOOKING BEYOND 18Z FRI, AN APPROACHING ARCTIC COLD FRONT WILL BRING
A FEW SHOWERS WITH POSSIBLE SUB-VFR CONDITIONS FRI. A PERIOD OF
GUSTY WINDS IS POSSIBLE FRI INTO SAT. VFR CONDITIONS ARE EXPECTED
FRI NIGHT THROUGH MON AS A COLD AIR MASS ARRIVES. -GIH
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...HARTFIELD
NEAR TERM...LUCHETTI
SHORT TERM...HARTFIELD
LONG TERM...KREN
AVIATION...HARTFIELD
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