208
FXUS62 KRAH 221132
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
635 AM EST SUN DEC 22 2024
SYNOPSIS
ARCTIC HIGH PRESSURE CENTERED OVER SOUTHERN ONTARIO WILL EXTEND
SOUTHWARD INTO NORTH CAROLINA AS IT DRIFTS OVER THE NORTHEAST AND
MID ATLANTIC STATES THROUGH EARLY MONDAY. THE HIGH WILL WEAKEN AND
PUSH OFFSHORE LATE MONDAY, ALLOWING FOR GRADUALLY WARMING
TEMPERATURES THROUGH MID WEEK.
NEAR TERM /TODAY AND TONIGHT/
AS OF 150 AM SUNDAY...
TODAY STILL APPEARS TO BE THE COLDEST DAY AND NIGHT OF THIS STRETCH,
AS THE SURFACE HIGH PRESSURE AND THERMAL TROUGH CENTERED TO OUR N
PASSES OVER LK ONTARIO AND EXTENDS DOWN THROUGH CENTRAL NC. HI-RES
AND LARGE SCALE MODELS AND ENSEMBLE SYSTEMS CONTINUE TO FAVOR
PLENTIFUL SUNSHINE TODAY, WITH A DRY/STABLE COLUMN, NO LOW LEVEL
MOISTURE ADVECTION INTO THE AREA, AND A FAST DRY NW FLOW ALOFT.
EXPECT NO MORE THAN A FEW PASSING HIGH THIN CLOUDS WITH PWS UNDER A
QUARTER INCH, LESS THAN 25% OF NORMAL. LOW LEVEL THICKNESSES ARE
EXPECTED TO BE 45-50 M BELOW NORMAL THIS MORNING, WITH FAIRLY
SHALLOW MIXING, FAVORING MUCH BELOW NORMAL HIGHS OF 36-43. CLEAR
SKIES THROUGH TONIGHT ALONG WITH VERY LIGHT TO CALM WIND WILL RESULT
IN EXCELLENT RADIATIONAL COOLING CONDITIONS, AS OVERNIGHT
THICKNESSES WILL STILL BE 30 M BELOW NORMAL. THIS WILL SUPPORT VERY
CHILLY LOWS IN THE MID TEENS TO LOWER 20S. -GIH
SHORT TERM /MONDAY/
AS OF 325 AM SUNDAY...
ANOTHER QUIET AND CHILLY DAY WITH LOTS OF SUNSHINE. THE SURFACE
HIGH'S CENTER WILL BE SHIFTING OFF THE NORTHEAST COAST MON, WHILE
CONTINUING TO EXTEND DOWN THROUGH CENTRAL NC. SURFACE FLOW FROM THE
NE OR ENE WILL REMAIN LIGHT, BUT FALLING SURFACE PRESSURES AND
INVERTED TROUGH DEVELOPMENT JUST OFF THE GA/SC COAST WILL KEEP NE
WINDS UP A BIT IN OUR SE. THE LOW-MID LEVEL FLOW (850-500 MB) WILL
BACK FROM NW TO SW, BUT THE DRY TRAJECTORY WILL CONTINUE WITH STABLE
AND WARM AIR ALOFT IMMEDIATELY UPSTREAM, SO SKIES WILL REMAIN MOSTLY
CLEAR. TEMPS WILL BE A BIT LESS CHILLY WITH SLOW AIR MASS
MODIFICATION, SO EXPECT HIGHS GENERALLY IN THE LOW-MID 40S. -GIH
LONG TERM /MONDAY THROUGH SATURDAY/
AS OF 410 AM SUNDAY...
* GUIDANCE IS QUICKLY EVOLVING WITH A STORM SYSTEM DEVELOPING ALONG
A COASTAL FRONT MONDAY NIGHT AND TUESDAY THAT PRODUCES SOME RAIN
NEAR THE COAST THAT EXTENDS INLAND WHICH COULD PRODUCE SOME BRIEF
FREEZING RAIN AROUND AND BEFORE DAYBREAK TUESDAY.
FORECAST CONFIDENCE IS LOWER THAN TYPICAL FOR MONDAY NIGHT THROUGH
TUESDAY NIGHT AS NWP GUIDANCE INDICATES A WEAK AREA OF LOW PRESSURE
JUST EAST OF SAVANNAH GA ON MONDAY EVENING. THIS STORM SYSTEM WILL
TRACK NORTHEAST ALONG AN INTENSIFYING COASTAL FRONT THAT SEPARATES A
COLD AND DRY AIRMASS ACROSS THE CAROLINA PIEDMONT WITH A RATHER WARM
AND MOIST AIRMASS OVER THE COASTAL WATERS. NWP GUIDANCE VARIES
CONSIDERABLY AND HAS RAPIDLY EVOLVED OVER THE PAST 12-24 HOURS WITH
THE AMOUNT AND NORTHWESTWARD EXTENT OF PRECIPITATION ACROSS CENTRAL
NC. THE 22/00Z GFS DEVELOPS VERY STRONG ISENTROPIC LIFT IN THE 290-
295K LAYER THAT PRODUCES NEARLY 1.2 INCHES OF QPF AT KFAY. NOTE THAT
THE 21/18Z GFS RUN HAD JUST 0.5 INCHES AND 21/12Z HAD 0.08 INCHES
HIGHLIGHTING THE RAPID CHANGE IN GUIDANCE. THE GFS IS AN OUTLIER IN
THE AMOUNT OF PRECIPITATION ACROSS NC WITH VARIOUS GEFS AND GEPS
MEMBERS PRODUCING MAINLY LIGHT PRECIPITATION WITH ENSEMBLE MEAN FOR
KFAY AROUND A 0.10 INCHES. THE 22/00Z NAM GENERATED ABOUT 0.17
INCHES AT KFAY, THE NEW 22/06Z HAS A TRACE AND THE VARIOUS EC EPS
MEMBERS PRODUCE VERY LIGHT PRECIPITATION AMOUNTS. FEEL THAT THE
LIGHTER PRECIPITATION AMOUNTS ARE MUCH MORE LIKELY AND THE INLAND
ARC OF MORE THAN AN INCH OF QPF IN THE GFS FROM KFAY UP TO KGSB IS
WAY OVERDONE. THESE HIGHER AMOUNTS ARE LIKELY PUSHING MODEL BLENDS
TO MUCH HIGHER AMOUNTS AND POPS AS WELL.
WILL INCLUDE SLIGHT CHANCE TO LOW CHANCE POPS AFTER MIDNIGHT TO 12Z
TUESDAY ACROSS THE SANDHILLS AND SOUTHERN COASTAL PLAIN. POPS WILL
EXPAND NORTHEAST AND NORTH DURING THE MORNING ON CHRISTMAS EVE,
PEAKING AROUND 40% IN THE SOUTHEAST AROUND MIDDAY BEFORE DROPPING TO
10% BY THE EVENING HOURS. EXPECT DRY CONDITIONS IN THE TRIAD AREA.
WITH A COLD ARCTIC AIRMASS IN PLACE ON MONDAY EVENING WITH DEW
POINTS IN THE TEENS, THERE IS SOME CONCERN THAT THE PRECIPITATION
COULD BEGIN AS A BRIEF PERIOD OF FREEZING RAIN. WILL NEED TO MONITOR
THIS AS SOME GUIDANCE SUCH AS THE NAM/RAP DEPICT WET BULB
TEMPERATURES NEAR TO BELOW FREEZING FROM NEAR KRWI TO KFAY AND
NORTHWESTWARD. EXPECT A NON-DIURNAL TEMP PATTERN WITH TEMPS STEADY
OR WARMING OVERNIGHT. FOR NOW IN THE DETERMINISTIC FORECAST WILL
INCLUDE MAINLY RAIN WITH A FEW PIXELS OF SHORT LIVED TRANSIENT
FREEZING RAIN ACROSS THE NORTHERN FRINGE OF THE PRECIPITATION. LOWS
ON TUESDAY MORNING WILL OCCUR JUST AFTER MIDNIGHT AND RANGE IN THE
UPPER 20S TO LOWER 30S. WITH LOTS OF CLOUDS AND A THREAT OF SPOTTY
RAIN HIGHS ON TUESDAY WILL BE CHILLY AND RANGE IN THE UPPER 40S TO
LOWER 50S ALTHOUGH THESE HIGHS COULD BE MUCH COLDER IF THE
PRECIPITATION IS MORE WIDESPREAD THAT CURRENTLY FORECAST.
THE NEXT STORM SYSTEM FEATURES A DEAMPLIFYING MID AND UPPER LEVEL
TROUGH ACROSS THE MS VALLEY ON CHRISTMAS MORNING WITH A SOUTHWEST
FLOW ACROSS THE CAROLINAS. THIS SYSTEM ADVANCE EAST AND WEAKENS AS
IT MOVES ACROSS THE AREA ON CHRISTMAS NIGHT AND EARLY THURSDAY WITH
LIMITED RAIN CHANCES AND SLIGHTLY BELOW AVERAGE TEMPERATURES. MID
AND UPPER LEVEL RIDGING ARRIVES ON FRIDAY AND SHIFTS EAST ON
SATURDAY PROMOTING A SOUTHWESTERLY FLOW OF MILDER AND MORE MOIST
AIR ACROSS THE CAROLINAS. AFTER GENERALLY DRY WEATHER LATE THURSDAY
INTO EARLY FRIDAY, RAIN CHANCES INCREASE A BIT AND TEMPERATURES WARM
TO ABOVE AVERAGE -BLAES
AVIATION /12Z SUNDAY THROUGH THURSDAY/
AS OF 635 AM SUNDAY...
CONFIDENCE IS HIGH THAT VFR CONDITIONS WILL CONTINUE ACROSS CENTRAL
NC TERMINALS FOR THE NEXT 24 HOURS, AS A DRY AND CHILLY AIR MASS
EXTENDS OVER THE REGION. LITTLE MORE THAN A FEW HIGH CLOUDS ARE
EXPECTED. SURFACE WINDS WILL BE FROM THE NE OR ENE UNDER 8 KTS.
LOOKING BEYOND 12Z MON, VFR CONDITIONS WILL HOLD THROUGH MON. THERE
IS A GOOD CHANCE OF SUB-VFR CONDITIONS WITH LIGHT RAIN MON NIGHT
THROUGH TUE AT RDU/FAY/RWI, WITH THE GREATEST CHANCES AT FAY/RWI, AS
WEAK LOW PRESSURE TRACKS NE ALONG THE NC COAST. VFR CONDITIONS
SHOULD THEN DOMINATE FROM TUE NIGHT THROUGH THU, ALTHOUGH A SHORT
PERIOD OF SUB-VFR CIGS IS POSSIBLE WED/WED NIGHT AS AN UPPER LEVEL
DISTURBANCE CROSSES THE REGION. -GIH
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...HARTFIELD
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