574
FXUS62 KRAH 182040
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
340 PM EST TUE FEB 18 2025
SYNOPSIS
CONTINENTAL POLAR HIGH PRESSURE WILL BUILD ACROSS THE MIDDLE
ATLANTIC AND CAROLINAS THROUGH TONIGHT. LOW PRESSURE WILL TRACK
ACROSS THE GULF AND SOUTH ATLANTIC COASTS WEDNESDAY AND WEDNESDAY
NIGHT. ARCTIC HIGH PRESSURE WILL FOLLOW AND MIGRATE FROM THE
NORTHERN PLAINS TO THE MIDDLE ATLANTIC, WHILE WEAKENING AND
MODIFYING, THROUGH NEXT WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 215 PM TUESDAY...
THE AFTERNOON SURFACE ANALYSIS REVEALS A COLD FRONT STRETCHING FROM
NORTHERN MS/AL INTO FAR EASTERN PORTIONS OF TN. ANOTHER BRANCH OF
THE FRONT EXTENDS ACROSS FAR EASTERN WV AND NORTHERN VA, WITH SINGLE
DIGIT DEWPOINTS ON THE NORTH SIDE OF THE FRONT. ALOFT, WATER VAPOR
SHOWS A TROUGH NEAR THE FOUR CORNERS THAT WILL BECOME AN OPEN WAVE
AS IT REACHES THE TN VALLEY AND SE US OVERNIGHT INTO TOMORROW
MORNING. THIS WAVE WILL BE AIDED BY ANOTHER SHORTWAVE TROUGH DIGGING
OUT OF MT INTO THE CENTRAL PLAINS. WITH TIME, GUIDANCE SHOWS THE
FRONT OVER VA SLIDING SOUTHWESTWARD IN A BACKDOOR FASHION OVERNIGHT
AS WEAK RIDGING SETS UP OVER THE MID-ATLANTIC. GUIDANCE APPEARS A
LITTLE FASTER WITH THE BACKDOOR FRONT, SUGGESTING LOWS IN THE MID
20S IN THE NORTH AND LOW 30S IN THE SOUTH. HOWEVER, GUIDANCE
SOMETIMES STRUGGLES WITH THE COLD AIR, BRINGING IT IN TOO FAST
ACROSS THE MOUNTAINS OF VA. WITH THAT, WE DID NOT GO AS LOW AS THE
MET WOULD SUGGEST, BUT HAVE LOWS MID/UPPER 20S IN THE NORTH AND
LOWER 30S IN THE FAR SOUTH. MOST OF THE WINTRY PRECIPITATION SHOULD
HOLD OFF UNTIL AFTER DAYBREAK WED, BUT INCREASING LOW-LEVEL WAA
AHEAD OF THE DEVELOPING SURFACE LOW COULD WARRANT LOW-END SNOW
CHANCES IN THE FAR NORTHWEST NEAR 12Z WED.
SHORT TERM /WEDNESDAY THROUGH THURSDAY/
AS OF 335 PM TUESDAY...
* NO CHANGE IN THE WINTER STORM WARNING AND ADVISORY AREAS FOR
WEDNESDAY INTO THURSDAY MORNING WITH THE AFTERNOON FORECAST UPDATE
DUE TO LOWER THAN NORMAL FORECAST CONFIDENCE.
* GREATEST TRAVEL IMPACTS AND POTENTIAL POWER OUTAGES WILL MOST
LIKELY OCCUR WEDNESDAY AFTERNOON INTO THE EARLY OVERNIGHT PERIOD.
* LINGERING SNOW SHOWERS THURSDAY MORNING WILL MOVE EAST AHEAD OF A
COLD FRONT WITH BREEZY WIND GUSTS OF 25 TO 35 MPH IN ITS WAKE.
THE OVERALL PATTERN CONSISTS OF A BACKDOOR COLD FRONT AND RESURGENCE
OF COLD/DRY ARCTIC AIR AHEAD THE ONSET OF WINTRY PRECIPITATION WED.
LIGHT PRECIPITATION WILL LIKELY BEGIN TO FALL AROUND 10 AM TOWARDS
THE SC/NC BORDER AND WILL RAPIDLY FILL ACROSS THE AREA INTO THE
EARLY AFTERNOON AS MID/UPPER FORCING FROM THE STRENGTHENING JET
STREAK MOVES OVERHEAD. THE BEST OVERLAP OF SYNOPTIC FORCING AND
INCREASING PRECIPITATION RATES WILL BE OVER THE EASTERN PIEDMONT AND
COASTAL PLAIN WED AFTERNOON TO AROUND 10 PM.
GIVEN THE LACK OF A FAVORABLE AND ANCHORED SURFACE HIGH LOCATION,
THE PREEXISTING ENVIRONMENT DEPOSITED BY THE BACKDOOR FRONT WILL
LIKELY DRIVE THE INITIAL ONSET P-TYPE DISTRIBUTION. CURRENT FORECAST
HIGHLIGHTS A VERY BROAD TRANSITION ZONE CENTERED AROUND US-64 WHERE
SNOW, SLEET, FREEZING RAIN/OR RAIN, WITH PREDOMINANTLY SNOW NORTH OF
THIS ZONE AND INITIALLY LIGHT RAIN TO ITS SOUTH. AS PRECIP RATES
INCREASE THROUGH THE AFTERNOON, SURFACE TEMPERATURES ARE EXPECTED TO
DROP BELOW FREEZING TOWARDS THE SURFACE WETBULB AND RESULT IN AN
EXPANDING AREA OF FREEZING RAIN OVER THE SANDHILLS AND INTO THE
SOUTHERN/CENTRAL COASTAL PLAIN. AT THE SAME TIME, STRENGTHENING
SOUTHERLY WAA ALOFT WILL BEGIN TO LIFT THIS TRANSITION ZONE FARTHER
NORTH, BUT WHERE ITS STALLS IS VERY UNCERTAIN. LATEST FORECAST
TRENDED TOWARDS WARMER/STRONGER WAA SOLUTIONS THAT TYPICALLY VERIFY
CLOSER WELL IN THESE SCENARIOS. THIS BRINGS THE SNOW/SLEET LINE TO
AROUND THE I-85 CORRIDOR INTO THE NORTHERN COASTAL PLAIN BEFORE
COLLAPSING BACK SOUTH OVERNIGHT.
OVERALL PRECIP DISTRIBUTION WILL BEGIN TO SPREAD EASTWARD AND
DECREASE IN INTENSITY AS DRY AIR ALOFT BEGINS TO SPREAD OVERHEAD
LATE WED INTO EARLY THURS. VERY LIGHT FREEZING DRIZZLE AND SPORADIC
SLEET WILL LIKELY BE THE PREDOMINANT P-TYPES DURING THIS TIME AS WE
LOSE SATURATION IN THE DGZ. SNOW ACCUMULATIONS WILL LIKELY BE
GREATEST NORTH OF US-64 AND RANGE FROM 1 TO 5 INCHES, LOCALLY HIGHER
AMOUNTS POSSIBLE TOWARDS THE VA/NC BORDER. ICE ACCUMULATIONS WILL BE
GREATEST SOUTH OF US-64 IN THE COASTAL PLAIN WITH TOTALS RANGING
FROM 0.05" TO AROUND 0.25". A COMBINATION OF SNOW, SLEET, AND
FREEZING RAIN IN THE ADVISORY AREAS MAY RESULT IN MINOR IMPACTS TO
TRAVEL AND WARRANT THE CONTINUATION OF THE ADVISORY AT THIS TIME.
A BRIEF LULL EARLY THURS MORNING WILL FILL BACK IN TOWARDS SUNRISE
AS A POTENT UPPER LOW AND STRONG FORCING OVERSPREADS THE AREA
THROUGH EARLY AFTERNOON. POINT SOUNDINGS SUGGEST STEEPENING LAPSE
RATES AND SATURATION RETURNING TO THE DGZ TO RESULT IN THE POTENTIAL
FOR SCATTERED SNOW SHOWERS. OVERALL ACCUMULATIONS ARE LIGHT AND
MINIMAL TO NO ACCUMULATIONS ARE EXPECTED. THURS AFTERNOON A STRONG
COLD FRONT WILL BEGIN TO MOVE ACROSS THE REGION FROM WEST TO EAST
AND RESULT IN STRONG WIND GUSTS OF 25 TO 35 MPH BEFORE DIMINISHING A
FEW HOURS AFTER SUNSET, ALTHOUGH CONTINUED CAA MAY CONTINUE SOME
GUSTINESS THROUGH THE EVENING.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
AS OF 330 PM TUESDAY...
- VERY COLD CONDITIONS THURSDAY AND FRIDAY NIGHTS FOLLOWED BY DRY
WEATHER AND A WARMING TREND INTO NEXT WEEK.
IN THE WAKE OF THE DEPARTING THE SNOWSTORM COLD ADVECTION WILL
CONTINUE INTO THURSDAY NIGHT. THICKNESSES ARE FORECAST TO DROP TO
NEAR 1260M BY FRIDAY MORNING. OVERNIGHT LOWS DROPPING INTO THE UPPER
TEENS TO LOWER 20S, ALONG WITH A STEADY 10 MPH WIND, WILL CAUSE WIND
CHILLS IN THE LOWER TEENS AND PERHAPS SOME SINGLE DIGITS. A CHILLY
BUT QUIET DAY IS EXPECTED ON FRIDAY, FOLLOWED BY CALM CONDITIONS
FRIDAY NIGHT. THIS WOULD NORMALLY RESULT IN COLDER OVERNIGHT LOWS
FRIDAY NIGHT GIVEN THE AIR MASS CHANGE, BUT MODELS SUGGEST SOME
CIRRUS OVERNIGHT IN RESPONSE TO A SHORTWAVE DIVING THROUGH THE MID
SOUTH, WHICH LOWERS CONFIDENCE IN COLDER OVERNIGHT LOWS.
NONETHELESS, IT SHOULD BE NOTED THAT THERE WILL BE A COUPLE FRIGID
NIGHTS.
A MODERATING TREND THEN BEGINS THROUGH THE WEEKEND INTO EARLY NEXT
WEEK, DESPITE CONTINUED BROAD MEAN TROUGHING ACROSS THE EASTERN US.
A COUPLE OF LOW AMPLITUDE SHORT WAVES ARE FORECAST TO MOVE THROUGH
THE TROUGH AND CROSS NC, AND SOME INDIVIDUAL GUIDANCE SUGGESTING
ENOUGH FORCING FOR SOME LIGHT PRECIP SATURDAY NIGHT AND AGAIN
TUE/TUE NIGHT. THIS IS NOT SUPPORTED BY A MAJORITY OF ENSEMBLE
MEMBERS AND SO WE WILL KEEP THE FORECAST DRY FOR NOW. HIGH
TEMPERATURES CLIMB EACH DAY AND REACH NEAR TO SLIGHTLY ABOVE NORMAL
BY THE MIDDLE OF NEXT WEEK.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AS OF 1215 PM TUESDAY...
THERE IS HIGH CONFIDENCE THAT VFR CONDITIONS WILL START THE TAF
PERIOD. ONLY BROKEN TO OVERCAST MID/HIGH CLOUDS ARE EXPECTED INTO
THE EARLY MORNING HOURS OF WED. GUIDANCE IS IN FAIRLY GOOD AGREEMENT
ON WINTRY PRECIPITATION SPREADING ACROSS THE TERMINALS WED MORNING,
ROUGHLY BETWEEN 13 AND 15Z, EARLIEST AT FAY. AS FOR PRECIPITATION
TYPES, FORECAST SOUNDINGS FROM A SUITE OF MODEL DATA SUGGESTS MAINLY
SNOW AT GSO/INT, A MIXTURE OF SNOW AND SLEET AT RDU/RWI, AND MAINLY
LIGHT RAIN TRANSITIONING TO FZRA AT FAY. MVFR CONDITIONS ARE
EXPECTED IN THIS WINTRY WEATHER, WITH A GOOD PROBABILITY OF IFR
TOWARDS THE TAIL END OF THE TAF PERIOD. NORTHEASTERLY WINDS WILL
GUST AT TIMES TO 18-22 KT WED MORNING INTO THE AFTERNOON AS THE
PRESSURE GRADIENT TIGHTENS.
OUTLOOK: IFR CONDITIONS IN A WINTRY MIX OF SNOW, SLEET, AND FREEZING
RAIN IS EXPECTED ACROSS THE TERMINALS WED INTO THU. LIGHT SNOW IS
MOST FAVORED AT GSO/INT, WITH A MIXTURE OF SNOW AND SLEET AT
RDU/RWI, AND MAINLY FZRA AT FAY. A SHORT PERIOD OF LIGHT SNOW IS
POSSIBLE ACROSS ALL TERMINALS THU MORNING BEFORE PRECIPITATION ENDS
MIDDAY THU. VFR RETURNS THU AFTERNOON AND CONTINUES THROUGH THE
REMAINDER OF THE PERIOD.
RAH WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 10 AM EST THURSDAY FOR
NCZ007>011-026>028-043-078.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 10 AM EST THURSDAY
FOR NCZ021>025-038>042-073>077-083>086-088-089.
SYNOPSIS...KREN/MWS
NEAR TERM...KREN
SHORT TERM...SWIGGETT
LONG TERM...BLS
AVIATION...KREN
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