734
FXUS62 KRAH 160525
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1225 AM EST THU JAN 16 2025
SYNOPSIS
ARCTIC HIGH PRESSURE WILL BUILD ACROSS NC TONIGHT. A DRY FRONTAL
ZONE WILL THEN WAVER OVER THE CAROLINAS THURSDAY THROUGH FRIDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 755 PM WEDNESDAY...
NOT MUCH CHANGE TO THE GOING FORECAST THROUGH TONIGHT. SURFACE
ANALYSIS REVEALS GENERALLY CALM WINDS ACROSS THE REGION AS THE HIGH
BUILDS IN FROM THE WEST AND NORTHWEST. A FEW HIGH CLOUDS WERE
STREAMING ACROSS FROM THE WEST AND SOUTHWEST TIED TO A SHORTWAVE
DIGGING INTO THE SOUTHEASTERN US. THESE CLOUDS WILL BE FEW AND FAR
BETWEEN AS THE SYSTEM REMAINS LARGELY TO OUR SOUTH. ANOTHER
SHORTWAVE OVER THE UPPER MS VALLEY DIGS INTO THE GREAT LAKES AND OH
VALLEY AND THIS HAS SOME MORE MID AND HIGH CLOUDS ASSOCIATED WITH
IT. THIS COULD BRING IN SOME PATCHY MID/HIGH CLOUDS TOWARD DAYBREAK,
BUT MOST OF THIS IS EXPECTED TO BE ACROSS OUR NORTH IN VA.
TEMPERATURES HAVE COOLED A FEW DEGREES BELOW OUR HOURLY VALUES. WITH
EXCELLENT RADIATIONAL COOLING, LOWERED LOWS A DEGREE OR TWO MORE FOR
TONIGHT. THAT STILL PUTS OUR LOWS IN THE UPPER TEENS TO AROUND 20,
WITH THE COLDEST LOCATIONS PERHAPS IN THE MID TEENS ACROSS THE
PIEDMONT.
SHORT TERM /THURSDAY AND THURSDAY NIGHT/
AS OF 350 PM WEDNESDAY...
A NRN STREAM TROUGH WILL PIVOT ACROSS AND OFFSHORE THE MIDDLE
ATLANTIC THIS PERIOD, WITH GLANCING, 30-60 METER MID-LEVEL HEIGHT
FALLS AND LIFT MAXIMIZED OVER CNTL NC LATE MORNING THROUGH MID-
AFTERNOON. AN ACCOMPANYING BAND OF BRIEFLY BROKEN ALTOCUMULUS AND
VIRGA WILL SWEEP ACROSS THE NRN PIEDMONT AND NRN COASTAL PLAIN
BETWEEN 15-20Z.
AT THE SURFACE, A QUASI-STATIONARY FRONT NOW INVOF THE SAVANNAH
BASIN WILL RETREAT NEWD AND ACROSS CNTL NC THROUGH THE AFTERNOON.
TEMPERATURES WITH THE PASSAGE OF THE FRONT WILL MODERATE TO AROUND
AVERAGE IN THE UPR 40S OVER THE FAR NE PIEDMONT/NRN COASTAL PLAIN TO
LWR-MID 50S ELSEWHERE - AN INCREASE OF 2-5 F FROM THE PREVIOUS
FORECAST BUT SUPPORTED BY THE WARM SECTOR 50S EVIDENT THIS AFTERNOON
OVER GA/SRN SC. IT WILL ALSO BECOME QUITE BREEZY TO WINDY IN THE
STRENGTHENING SWLY FLOW BEHIND THE PASSING WARM FRONT, WITH
AFTERNOON GUSTS UP TO 25-30 KTS, LOCALLY HIGHER AROUND MEB/FAY AND
INT/GSO. A SEGMENT OF THE FRONTAL ZONE WILL COLLAPSE BACK SEWD
ACROSS CNTL NC THU NIGHT, AS A FRONTAL WAVE DEVELOPS AND DEEPENS OFF
THE MIDDLE ATLANTIC COAST. CAA AND NWLY STIRRING WILL FAVOR NEAR
AVERAGE LOW TEMPERATURES OF MOSTLY 26-31 F.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
AS OF 315 PM WEDNESDAY...
HIGHLIGHTS:
-THERE ARE TWO POTENTIAL WEATHER SYSTEMS THAT COULD
CREATE WINTRY WEATHER BETWEEN FRIDAY AND THE MIDDLE TO LATE NEXT
WEEK, WITH AN ARCTIC BLAST IN BETWEEN.
-THE FIRST WEATHER SYSTEM COMES ON SATURDAY WITH A HIGH PROBABILITY
OF RAIN, FOLLOWED BY THE POTENTIAL FOR ANOTHER PERIOD OF LIGHTER
RAIN THAT COULD MIX WITH SOME SNOW, ESPECIALLY ACROSS NORTHERN AREAS
ON SUNDAY.
-BEHIND THIS SYSTEM WILL BE AN ARCTIC BLAST THAT MAY RIVAL
TEMPERATURES IN LATE DECEMBER 2022 WHEN LOW TEMPERATURES REACHED THE
SINGLE DIGITS AND HIGHS WERE IN THE 20S.
-THE NEXT WEATHER SYSTEM HAS THE POTENTIAL TO BE A COASTAL LOW WITH
WINTRY PRECIPITATION ACROSS INTERIOR NORTH CAROLINA MID TO LATE
WEEK. HOWEVER, CONFIDENCE IS VERY LOW AT THIS POINT DUE TO
SIGNIFICANT DIFFERENCES IN MODEL RUNS REGARDING HOW FAR EAST OR WEST
THE LOW TRACKS
MORE DETAILS:
THE OVERALL WEATHER PATTERN WILL FEATURE A BRIEF PERIOD OF SHORTWAVE
RIDGING ON FRIDAY AHEAD OF THE REESTABLISHMENT OF A VERY DEEP AND
COLD LONGWAVE TROUGH OVER THE EASTERN US THAT PERSISTS THROUGH NEXT
WEEK. ON THE FRONT END, A LEAD SOUTHERN STREAM SHORTWAVE IS
FORECAST TO RACE ACROSS THE DEEP SOUTH ON FRIDAY AND BRING
WIDESPREAD RAIN TO THE REGION SATURDAY. MODELS HAVE BEEN CONSISTENT
AND INDICATING THAT THE HEAVIER QPF WILL SPREAD ACROSS GEORGIA AND
SOUTH CAROLINA, MORE ASSOCIATED WITH A WAVE OF LOW PRESSURE TRACKING
ACROSS A SLOWLY NORTHWARD RETREATING POLAR FRONT AND EVENTUALLY
DEVELOPING INTO A SURFACE LOW OFF THE CAROLINA COAST SATURDAY NIGHT,
WHILE THERE IS A DRYING TREND AS THE PRECIPITATION REACHES NORTH
CAROLINA INTO VIRGINIA. OVERALL QPF IS FORECAST TO BE IN THE 0.25-
0.5 RANGE ON SATURDAY.
BEHIND THIS AREA OF RAIN THE ARCTIC FRONT IS FORECAST TO CROSS
CENTRAL NORTH CAROLINA ON SUNDAY. MODELS HAVE BEEN FAIRLY CONSISTENT
IN SHOWING A WAVE OF LOW PRESSURE DEVELOPING ALONG THE FRONT IN
RESPONSE TO THE DEEP UPPER LEVEL TROUGH, WHICH CONSEQUENTLY CAUSES
PRECIPITATION TO BREAK OUT OVER THE PIEDMONT SUNDAY OR SUNDAY NIGHT.
THIS IS TYPICALLY A SCENARIO WHERE THE ARRIVAL OF COLD AIR THAT
COULD CAUSE A CHANGE OVER TO SNOW IS TOO LATE, BUT GIVEN THE
POTENTIAL FOR A WAVE OF LOW PRESSURE AND STRONG DEEP LAYER LIFT, IT
SEEMS MORE PLAUSIBLE THAT A MIX OF RAIN AND SNOW COULD DEVELOP,
ESPECIALLY ACROSS COUNTIES CLOSER TO VIRGINIA. THE GFS EVEN
INDICATES SOME LOCALLY HIGHER QPF NEAR A QUARTER OF AN INCH ACROSS
NORTHEAST NORTH CAROLINA, SO THERE ARE DETAILS THAT WILL BE WORTH
WATCHING OVER THE NEXT SEVERAL MODEL RUNS.
FOLLOWING THE ARCTIC FRONT, THE ARCTIC AIR MASS USHERED IN AHEAD OF
A 1050 MB HIGH-PRESSURE OVER THE CENTRAL PLAINS IS FORECAST TO HAVE
THICKNESSES THAT BOTTOM OUT BELOW 1230 M. GUIDANCE IS INDICATING
LOWS WELL INTO THE TEENS IF NOT NOT SINGLE DIGITS IN SOME AREAS BY
TUESDAY AND HIGHS IN THE 20S.
THE NEXT BIG QUESTION IS HOW SHORTWAVES MOVING THROUGH THE LONGWAVE
TROUGH COULD CAUSE CYCLOGENESIS IN THE GULF OF MEXICO OR ALONG THE
SOUTH EAST COAST, AND HOW FAR WEST PRECIPITATION EXTENDS INTO A
SIGNIFICANTLY COLD AIR MASS ACROSS THE CAROLINAS. MODELS HAVE BEEN
BACK-AND-FORTH BETWEEN OFFSHORE PRECIPITATION AND PRECIPITATION
EXTENDING WELL INTO NORTH CAROLINA, WITH ALMOST REGULAR FLIP-
FLOPPING BETWEEN MODEL CYCLES. PROBABILISTIC FORECASTS BASICALLY
SHOW AT LEAST A SLIGHT CHANCE OF SNOW BETWEEN TUESDAY AND THURSDAY,
WHICH HIGHLIGHTS THE UNCERTAINTY, AS IS VERY UNLIKELY TO SNOW FOR
THAT LONG. INSTEAD, THE MODELS ARE HAVING A HARD TIME, FOCUSING ON
ONE SPECIFIC PERIOD OF PRECIPITATION. FOR NOW, WE WILL CONTINUE TO
INDICATE A SLIGHT CHANCE OF SNOW WITH THE CAVEAT THAT THIS WILL
DEFINITELY CHANGE AND THE SYSTEM COULD HAVE ANYWHERE FROM NO IMPACT
TO SIGNIFICANT IMPACT.
AVIATION /06Z THURSDAY THROUGH MONDAY/
AS OF 1225 AM THURSDAY...
24 HOUR TAF PERIOD: HIGH CONFIDENCE VFR CONDITIONS WILL PREVAIL
THROUGH THE TAF PERIOD.
SURFACE HIGH PRESSURE ACROSS THE AREA WILL SINK SOUTH TOWARDS THE
NORTHERN GULF COAST AND DEEP SOUTH, WHICH WILL ALLOW SURFACE WINDS
TO BECOME SWLY AFTER DAYBREAK. WINDS WILL INCREASE AHEAD OF AN
AMPLIFYING NORTHERN STREAM MID-LEVEL TROUGH THAT WILL SWING THROUGH
THE AREA DURING THE AFTERNOON. EXPECT FREQUENT SWLY GUSTS OF 20-
30KTS BEGINNING MIDDAY AND CONTINUING INTO THE MID AFTERNOON BEFORE
DIMINISHING. THE UPPER TROUGH WILL ALSO LEAD TO A FLEETING PERIOD OF
5-10KFT BROKEN CEILINGS ACROSS THE NORTHERN TERMINALS DURING THE
AFTERNOON.
GUSTS WILL SUBSIDE AND SKIES WILL CLEAR OUT IN THE EVENING. A 30-
40KT WLY LLJ AT 2000 FT AGL WILL RESULT IN A CHANCE OF LOW-LEVEL
WIND SHEAR THROUGH AROUND 06Z, BEFORE DIMINISHING.
OUTLOOK: DRY VFR CONDITIONS ARE EXPECTED THROUGH FRIDAY. A COUPLE OF
FRONTAL SYSTEMS AND ACCOMPANYING RAIN, SUB-VFR FLIGHT RESTRICTIONS,
AND MARGINAL LOW-LEVEL WIND SHEAR ACROSS CENTRAL NC THIS WEEKEND.
FIRE WEATHER
AS OF 400 PM WEDNESDAY...
THE PASSAGE OF A WARM FRONT ON THU WILL RESULT IN BOTH MUCH MILDER
CONDITIONS, WITH MIN RH BETWEEN 25-35 PERCENT, AND STRENGTHENING
SWLY SURFACE WINDS INTO THE TEENS MPH AND WITH AFTERNOON GUSTS
BETWEEN 25-35 MPH. INCREASED FIRE DANGER MAY RESULT.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...KREN
SHORT TERM...MWS
LONG TERM...BLS
AVIATION...CBL/MWS
FIRE WEATHER...MWS
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