373
FXUS62 KRAH 190608
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
107 AM EST SUN JAN 19 2025
SYNOPSIS
AN AREA OF LOW PRESSURE OVER THE DEEP SOUTH WILL LIFT THROUGH THE
AREA ON SUNDAY. ARCTIC HIGH PRESSURE WILL BUILD IN BEHIND A COLD
FRONT LATE SUNDAY AFTERNOON AND BRING BITTER COLD TEMPERATURES INTO
THE REGION THROUGH THE MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 830 PM SATURDAY...
THE EVENING SURFACE ANALYSIS SHOWS A BROAD AREA OF LOW PRESSURE
ACROSS CENTRAL TO SOUTHERN AL, WITH A TRAILING COLD FRONT DRAPED
SOUTHWEST TO NORTHEAST FROM CENTRAL MS INTO THE OH VALLEY. A WARM
FRONT EXTENDED FROM THE SURFACE LOW INTO SOUTHERN GA. IN RESPONSE TO
A TROUGH BECOMING POSITIVELY TILTED AS IT TRACKS INTO THE TN VALLEY
OVERNIGHT, ISENTROPIC ASCENT COMBINED WITH MOIST ADVECTION AND MID-
LEVEL FRONTOGENESIS WILL OVERSPREAD THE REGION. THE SURFACE LOW IS
FORECAST TO REACH NORTH-CENTRAL SC BY MORNING, WHILE THE LOW-LEVEL
CENTER TRACKS ALONG WESTERN NC. LIFT FROM THE COMBINED FACTORS WILL
MAXIMIZE AFTER MIDNIGHT AND ESPECIALLY TOWARD THE EARLY MORNING
HOURS OF SUN. THE GREATEST LIFT APPEARS ORIENTED FROM THE SANDHILLS
INTO THE COASTAL PLAIN. ALL OF THIS WILL SUPPORT RAIN OVERSPREADING
MUCH OF THE AREA OVERNIGHT.
CURRENT OBSERVATIONAL TRENDS SHOW A MIXTURE OF LOW CLOUDS STARTING
TO BUILD IN FROM THE WEST AHEAD OF THE 925 MB LOW. WHERE SKIES
REMAIN CLEAR, SOME PATCHY FOG HAS DEVELOPED, MAINLY FROM THE EASTERN
SANDHILLS TO THE COASTAL PLAIN. WE WILL CONTINUE TO MONITOR THESE
VISIBILITY TRENDS AND ISSUE AN ADVISORY/STATEMENT IF NEEDED.
VISIBILITIES ARE EXPECTED TO DROP MORESO AFTER MIDNIGHT AS
SATURATION OCCURS AHEAD OF AND WITH THE ONSET OF RAIN.
THE MAIN CHANGE IN THIS FORECAST UPDATE WAS TO INCREASE RAIN CHANCES
ALONG/EAST OF US-1 DUE TO THE AFOREMENTIONED LIFT AND MOISTURE. WE
ALSO INCREASED QPF AMOUNTS. THE HREF SUGGESTS UP TO A QUARTER INCH
OR MORE IS POSSIBLE BY DAYBREAK OVER THE SANDHILLS AND CENTRAL
COASTAL PLAIN. FURTHER NORTH AND WEST, A TENTH OF AN INCH OR LESS IS
EXPECTED. LOWS TONIGHT ARE EXPECTED TO BE IN THE UPPER 30S TO MID
40S, COOLEST IN THE NE. THESE LOW WILL LIKELY BE FELT EARLY TONIGHT,
GRADUALLY RISING OVERNIGHT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
AS OF 250 PM SATURDAY...
AS THE SURFACE LOW TREKS UP THE MID-ATLANTIC COAST SUNDAY MORNING
MULTIPLE ROUNDS OF RAIN ARE EXPECTED ACROSS CENTRAL NC. WHILE THE
EXACT TRACK OF THE LOW IS STILL A LITTLE UNCERTAIN WEATHER IT WILL
TREK UP THE MID-ATLANTIC INLAND OR JUST OFFSHORE, A WARM FRONT
ASSOCIATED WITH IT WILL RESULT IN ALL RAIN FOR THIS SYSTEM. BY
SUNDAY AFTERNOON THE LOW IS EXPECTED TO BE TO TO THE NORTHEAST OF
THE AREA AND PRECIP WILL BE EXITING THE AREA WEST TO EAST. DRYING
ALOFT WILL SIGNIFICANTLY DECREASE CHANCES OF ICE IN THE CLOUD TO
SUPPORT A CHANGE-OVER TO SNOW ACROSS THE NORTHERN COUNTIES DURING
THE LAST LITTLE PUSH OF PRECIP ACROSS THE NORTHERN PIEDMONT LATE
AFTERNOON/EARLY EVENING AS THE COLD DRY ARCTIC AIR POURS INTO THE
AREA. THUS NO SNOW IS EXPECTED TO OCCUR DURING THIS SUNDAY SYSTEM.
WINDS WILL PICK UP IN THE LATE MORNING THROUGH THE AFTERNOON AS THE
COLD FRONT MOVES ACROSS THE REGION WITH 25-30 MPH GUSTS FROM THE
WEST OR NORTHWEST. TEMPERATURES SUNDAY MORNING WILL BE IN THE LOW
40S ACROSS THE NORTHERN PIEDMONT AND UPPER 40S ACROSS THE SANDHILLS.
HIGHS WILL REACH THE MID 40S NORTH, AND UPPER 50S SOUTH WITH
POSSIBILITY OF SOME LOWER 60S CLOSER TO THE COAST.
SUNDAY NIGHT AS COLD ARCTIC HIGH CONTINUES TO PUSH SOUTH ACROSS THE
MS VALLEY, TEMPERATURES WILL QUICKLY DROP AS SKIES CLEAR OVERNIGHT.
LOWS SUNDAY NIGHT INTO MONDAY MORNING WILL BE IN THE MID TO UPPER
TEENS IN THE NORTH TO LOW TO MID 20S ELSEWHERE.
MONDAY WILL BE DRY, AND FRIGID WITH MORNING WIND CHILL TEMPERATURES
IN THE SINGLE DIGITS FOR THE NW PIEDMONT, AND MID UPPER TEENS TO LOW
20S ELSEWHERE. HIGHS WILL BE IN THE MID 20S NW TO LOW/MID 30S SE.
TEMPERATURES WILL CRASH AGAIN MONDAY NIGHT WITH LOWS IN THE TEENS
ACROSS ALL OF CENTRAL NC. LOWS WILLS WILL BE IN THE LOW TEENS IN THE
NW, TO UPPER TEENS IN THE SE. WIND CHILLS WILL RANGE FROM SINGLE
DIGITS TO LOW TEENS ACROSS THE AREAS ONCE AGAIN TUESDAY MORNING.
LONG TERM /TUESDAY THROUGH SATURDAY/
AS OF 455 PM SATURDAY...
* FORECAST CONFIDENCE REMAINS HIGH FOR A CONTINUATION OF WELL BELOW
AVERAGE TEMPERATURES THIS PERIOD, MAXIMIZED WITH DEPARTURES FROM
NORMAL OF 15-25 F MID-WEEK.
* FORECAST CONFIDENCE IS LOW REGARDING THE NORTHERN EXTENT OF
(WINTRY) PRECIPITATION ACROSS CNTL-ERN NC, AS GENERALLY
FLAT/SUPPRESSED/WEAK LOW PRESSURE TRACKS FROM THE GULF OF MEXICO TO
WELL OFFSHORE THE SOUTH AND SOUTHERN MIDDLE ATLANTIC COASTS TUE-
EARLY WED.
A HIGHLY AMPLIFIED MID/UPR-LEVEL PATTERN WILL BE CHARACTERIZED BY A
RIDGE OVER THE ERN PACIFIC AND MEAN TROUGHS THAT WILL PIVOT ACROSS
THE CNTL-ERN US. THE FIRST OF THOSE TROUGHS, AND MOST INFLUENTIAL
FOR THE THREAT OF WINTRY PRECIPITATION (SNOW) INTO CNTL NC, WILL BE
A POSITIVELY-TILTED AND AT LEAST PARTIALLY PHASED TROUGH THAT WILL
EXTEND FROM THE UPR GREAT LAKES TO THE SOUTHWEST AT 12Z TUE AND
PIVOT ACROSS AND OFFSHORE THE SOUTH AND SRN MIDDLE ATLANTIC THROUGH
WED. IT SHOULD BE NOTED THAT THE MOST-BASAL OF THOSE SHORTWAVE
PERTURBATIONS JUST ENTERED THE NORTH AMERICAN RAOB NETWORK NEAR
ANNETTE ISLAND AND YAKUTAT, ALASKA THIS MORNING. FURTHER SAMPLING OF
THIS FEATURE ACROSS WRN BRITISH COLUMBIA AND THE PACIFIC NORTHWEST
THROUGH 12Z SUNDAY MAY BETTER RESOLVE ITS PRESENCE AND DOWNSTREAM
SYNOPTIC INFLUENCE AND ULTIMATELY DECREASE ABOVE AVERAGE MODEL
SPREAD IN SOLUTIONS OF ITS IMPACT TO SRN US WINTRY WEATHER TUE-TUE
NIGHT. THE OTHER SHORTWAVE PERTURBATIONS FORECAST TO COMPRISE THE
POSITIVE-TILT TROUGH SHOULD ALSO BECOME BETTER-RESOLVED FOR MODEL
INITIAL CONDITIONS, AS THEY DIG SHARPLY SSEWD FROM THE NORTHWEST
TERRITORIES AND YUKON TO THE CNTL CANADIAN PRAIRIES. LOW AMPLITUDE
SHORTWAVE RIDGING WILL THEN PROGRESS ACROSS AND OFFSHORE THE MIDDLE
AND SOUTH ATLANTIC LATER WED-WED NIGHT, DOWNSTREAM OF A TROUGH THAT
WILL RELOAD AND PIVOT FROM THE GREAT PLAINS AND MS VALLEY TO THE
EAST COAST THROUGH SAT.
AT THE SURFACE, ARCTIC HIGH PRESSURE WILL INITIALLY SPRAWL FROM THE
CNTL GREAT BASIN TO THE MIDDLE ATLANTIC, THEN GRADUALLY WEAKEN AS IT
MIGRATES EWD AND BECOMES CENTERED OVER THE MIDDLE ATLANTIC THROUGH
THE END OF THE WEEK. A FRONTAL ZONE WILL BE SUPPRESSED WELL-
SOUTHWARD ACROSS THE SUB-TROPICS, FROM THE GULF OF MEXICO TO THE
SWRN N. ATLANTIC, ALONG THE SRN/EQUATORWARD DRAPE OF THE EXPANSIVE
ARCTIC HIGH AND AIRMASS THROUGH MID-WEEK; AND MODEL AGREEMENT IS
RELATIVELY HIGH REGARDING ONLY WEAK/FLAT FRONTAL WAVE DEVELOPMENT
ALONG THAT FRONTAL ZONE FROM THE GULF OF MEXICO TO OFFSHORE THE
SOUTH ATLANTIC COAST TUE-TUE NIGHT. WHILE SOME MODELS DEPICT MORE
SUBSTANTIAL DEEPENING OF THE LOW AS IT TRACKS BETWEEN CAPE HATTERAS
AND BERMUDA, ANY SUCH DEVELOPMENT AND DEEPENING WOULD BE TOO LATE
AND INCONSEQUENTIAL FOR SIGNIFICANT IMPACTS TO CNTL NC. THE
AFOREMENTIONED RE-LOADING OF THE TROUGH ALOFT INITIALLY INTO THE
CNTL US MAY ALLOW THE SURFACE FRONTAL ZONE AND SUBSEQUENT
CYCLOGENESIS TO BUCKLE POLEWARD AND NEARER THE MIDDLE ATLANTIC AND
SRN NEW ENGLAND COASTS LATER IN THE WEEK, WITH POSSIBLE ADDITIONAL,
LOW CONFIDENCE PRECIPITATION IMPACTS INTO CNTL NC.
THE PREVIOUSLY VERY WET SOLUTIONS ON THE EXTREME NWRN EDGE OF THE
GUIDANCE ENVELOPE, LED BY THE GEM AND GEPS, HAVE TRENDED SOUTHWARD
AND DRIER AND NOW FORM A STRONG CONSENSUS CLUSTER OF GUIDANCE WITH
EPS SOLUTIONS OF THE PAST COUPLE OF DAYS. WHILE THIS CLUSTER
APPEARS TO BE A FAVORED AND REASONABLE SOLUTION FOR MEASURABLE SNOW
AND LOW TO MODERATE IMPACTS ACROSS E-CNTL NC, THE MUCH DRIER AND SWD-
SUPPRESSED GFS AND GEFS SOLUTIONS HAVE SUPPORT OF THE EC-AIFS AND
PRODUCE VERY LITTLE SNOW INTO CNTL AND EVEN SERN NC. FORECAST
CONFIDENCE CONSEQUENTLY REMAINS BELOW AVERAGE AT THIS TIME.
VERY COLD CONDITIONS, AND DRY ONES, WED-WED NIGHT WILL THEN
GRADUALLY MODERATE INTO THE UPCOMING WEEKEND, AS THE ARCTIC HIGH AND
AIRMASS GRADUALLY WEAKEN AND LOSE INFLUENCE. AS THE ARCTIC AIR DOES
SO, HOWEVER, SUFFICIENTLY COLD AIR MAY REMAIN IN PLACE TO PRESENT
ADDITIONAL P-TYPE CONCERNS AS MOISTURE IS DRAWN NWWD WITH THE
AFOREMENTIONED OFFSHORE FRONTAL ZONE AND POSSIBLE RENEWED
CYCLOGENESIS NEAR THE MIDDLE ATLANTIC COAST. FOR NOW, AND GIVEN HIGH
UNCERTAINTY, JUST A SLIGHT CHANCE OF MIXED PRECIPITATION WILL BE
ADVERTISED MAINLY OVER THE ERN HALF OF CNTL NC THU INTO FRI.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
AS OF 100 AM SUNDAY...
A DEVELOPING WAVE OF LOW PRESSURE OVER THE CAROLINAS WILL RIDE NE
ALONG A COMPLEX FRONTAL ZONE THAT WILL MOVE THROUGH THE AREA THROUGH
THE AFTERNOON. A MIXTURE OF STRATUS AND FOG HAS DEVELOPED AHEAD OF
THE SYSTEM, WITH FLIGHT RESTRICTIONS EXPECTED TO LOWER TO LIFR AT
ALL TAF SITES OVERNIGHT. RAIN WILL BEGIN TO OVERSPREAD CENTRAL AND
EASTERN NC AS A WARM FRONT LIFTS NORTH INTO THE AREA. THIS AREA OF
RAIN SHOULD MOVE NORTH INTO VA ~ 18Z, FOLLOWED BY ISOLATED TO WIDELY
SCATTERED SHOWERS THROUGH 00Z AS THE ARCTIC COLD FRONT MOVES EAST
THROUGH THE AREA. THE RESULTANT STRONG COLD DRY AIR ADVECTION WILL
SCATTER OUT THE SUB-VFR RESTRICTIONS FROM SW TO NE BETWEEN 18Z-02Z.
ADDITIONALLY, WESTERLY AND NWLY GUSTINESS OF 20-25KTS WILL DEVELOP.
THE GUSTINESS COULD LINGER INTO THE OVERNIGHT HOURS.
OUTLOOK: VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY. FORECAST
UNCERTAINTY IS HIGH, HOWEVER A POTENTIAL WINTER STORM SYSTEM COULD
BRING SUB-VFR RESTRICTIONS IN THE FORM OF SNOW TUESDAY AFTERNOON
THROUGH EARLY WEDNESDAY.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
JANUARY 20:
KGSO: 29/1983
KRDU: 28/1970
JANUARY 21:
KFAY: 31/1983
JANUARY 22:
KGSO: 29/2014
KRDU: 27/1970
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...SWIGGETT/CBL
NEAR TERM...KREN
SHORT TERM...CA
LONG TERM...MWS
AVIATION...CBL
CLIMATE...RAH
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