859
FXUS62 KRAH 211100
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
600 AM EST SAT DEC 21 2024
SYNOPSIS
ARCTIC HIGH PRESSURE CENTERED OVER ONTARIO CANADA THIS MORNING WILL
EXTEND SOUTHWARD INTO NORTH CAROLINA AS IT DRIFTS SOUTHEASTWARD OVER
THE NORTHEAST AND MID ATLANTIC STATES OVER THE WEEKEND. HIGH
PRESSURE WILL REMAIN IN CONTROL THROUGH EARLY NEXT WEEK, WITH DRY
WEATHER AND GRADUALLY WARMING TEMPERATURES.
NEAR TERM /TODAY AND TONIGHT/
AS OF 210 AM SATURDAY...
EXPECT FAIR AND FRIGID CONDITIONS TO START THE WEEKEND. THE AXIS OF
THE MEAN LONGWAVE TROUGH OVER E NOAM WILL SHIFT TO OUR E THIS
MORNING, AND THE STOUT CYCLONIC NW STEERING FLOW WILL ALLOW THE MUCH
COLDER AIR MASS TO FINALLY SPILL PAST THE HIGHER TERRAIN AND INTO
CENTRAL NC FROM THE NW AND N. THE COLUMN WILL BE GENERALLY QUITE DRY
WITH HIGH MID STABILITY IN THE MID LEVELS, FAVORING PLENTY OF
SUNSHINE, ALTHOUGH WE MAY SEE A FEW MID CLOUDS LATER IN THE DAY AS A
WEAK/SHEARED VORTICITY LOBE DIVES SE INTO THE MEAN TROUGH BASE AND
THROUGH THE CAROLINAS. LOW LEVEL THICKNESSES ARE EXPECTED TO BE
AROUND 20 M BELOW NORMAL THIS MORNING, SO DESPITE GOOD INSOLATION
AND DECENT MIXING, HIGHS SHOULD ONLY BE IN THE 40S TO NEAR 50
AREAWIDE. AFTER A MINOR UPTICK DURING THE DAY, THICKNESSES WILL
PLUMMET TONIGHT TO THEIR EXPECTED LOWEST POINT DURING THIS STRETCH,
AROUND 1265-1275 M BY SUN MORNING. DESPITE A LINGERING LIGHT BREEZE
FROM THE N OVERNIGHT, THE CLEAR SKIES WILL FOSTER DECENT RADIATIONAL
COOLING, SUPPORTING LOWS FROM THE MID TEENS TO MID 20S. -GIH
SHORT TERM /SUNDAY AND SUNDAY NIGHT/
AS OF 250 AM SATURDAY...
THIS WILL BE THE COLDEST DAY AND NIGHT OF THIS STRETCH, AS THE LOW
LEVEL THERMAL TROUGH SETTLES ACROSS CENTRAL NC. DETERMINISTIC MODELS
AND ENSEMBLE SYSTEMS CONTINUE TO FAVOR LOTS OF SUNSHINE SUN, WITH A
DRY AND STABLE COLUMN AND PWS UNDER A QUARTER INCH, LESS THAN 25% OF
NORMAL, NO LOW LEVEL MOISTURE ADVECTION INTO THE AREA, AND A DRY
FAST NW FLOW ALOFT. THE COLD SURFACE HIGH'S CENTER WILL TRACK FROM
NEAR MONTREAL SE OVER THE NORTHEAST STATES WHILE STILL EXTENDING
DOWN THROUGH OUR AREA. WITH THICKNESSES 40-50 M BELOW NORMAL TO
START THE DAY AND MORE SHALLOW MIXING COMPARED TO TODAY, EXPECT
HIGHS IN THE UPPER 30S TO LOWER 40S, PERHAPS SOME MID 40S NEAR THE
SC BORDER. LIGHT TO CALM WIND AND CLEAR SKIES WILL RESULT IN
EXCELLENT RADIATIONAL COOLING CONDITIONS SUN NIGHT, SUGGESTING VERY
CHILLY LOWS IN THE MID TEENS TO LOWER 20S. -GIH
LONG TERM /MONDAY THROUGH FRIDAY/
AS OF 235 AM SATURDAY...
ARCTIC HIGH PRESSURE WILL EXTEND INTO THE AREA FROM THE MID-ATLANTIC
ON MON. THIS SHOULD BE OUR COLDEST DAY OF THE WEEK WITH HIGHS 9-12
DEGREES BELOW NORMAL IN THE LOW TO MID 40S AND LOWS IN THE 20S.
RIDGING ALOFT OVER THE TN VALLEY WILL FLATTEN AND BECOME QUASI-ZONAL
INTO TUE. AS THIS HAPPENS, THE ARCTIC HIGH WILL RETREAT OFF THE NE
US COAST AND SHOULD ALLOW THE CLASSICAL CAD WEDGE TO WEAKEN. THIS
ALONG WITH RISING LOW-LEVEL THICKNESSES SHOULD SUPPORT HIGHS NEAR
NORMAL IN THE LOW TO MID 50S.
MODELS AND THEIR RESPECTIVE ENSEMBLES CONTINUE TO SHOW A SHORTWAVE
OVER THE CENTRAL TO SOUTHERN PLAINS MOVING EAST OVER THE CAROLINAS
LATE WED INTO THU. THESE SOLUTIONS STILL DIFFER ON ITS STRENGTH,
HOWEVER, WITH SOME SHOWING THE SHORTWAVE WEAKENING IN THE EMBEDDED
RIDGING OVER THE AREA. COUPLED TO THIS, AT THE SURFACE, GUIDANCE
SHOWS A DEVELOPING OFFSHORE INVERTED TROUGH AND WEAK LOW PRESSURE
MOVING NORTH OFF THE NC COAST. SOME SOLUTIONS INDICATE THE OFFSHORE
TROUGH COULD LINGER INTO FRI. MEANWHILE, A SYSTEM TO OUR NORTH LATE
TUE SHOULD BRING A BACKDOOR FRONT THROUGH THE REGION EARLY WED. A
1032+ MB HIGH PRESSURE IN SOUTHERN QUEBEC IS FAVORED IN THE ENSEMBLE
DATA TO THEN EXTEND INTO OUR AREA THROUGH FRI.
AS FOR SPECIFICS, HIGHS DURING THIS TIME COULD BE TRICKY BUT SHOULD
BE SLIGHTLY BELOW NORMAL UNDER A HYBRID OR EVEN IN-SITU CAD SETUP.
THE OFFSHORE TROUGH AND UPPER-LEVEL SYSTEM COULD FAVOR ISENTROPIC
ASCENT ATOP THE CAD WEDGE AND KEEP HIGHS IN THE UPPER 40S N AND W TO
LOW TO MID 50S IN THE S AND SE. THE CMC/GEPS ARE THE EARLIEST AND
WETTEST FOR RAIN CHANCES TIED TO THE OFFSHORE LOW/TROUGH, BRINGING
RAIN IN TUE NIGHT, WHILE THE EPS/ECMWF/GFS/GEFS ARE DRIER AND
SUPPRESS MORE OF THE OFFSHORE SYSTEM DUE TO STRONGER RIDGING FROM
THE SURFACE HIGH. PREDICTABILITY REMAINS LOW AS A RESULT. OUR
FORECAST TRENDS TOWARD THE ENSEMBLE SOLUTIONS, WHICH STILL FAVOR
LATE WED INTO THU FOR THE HIGHEST RAIN CHANCES. ANOTHER LATE-WEEK
SYSTEM COULD APPROACH LATE FRI INTO SAT FROM THE MID MS VALLEY,
THOUGH HIGHER SPREAD EXISTS WITH THIS STORM. FOR NOW, HIGHEST RAIN
CHANCES WITH THIS WOULD BE OVER THE WESTERN PIEDMONT PER ENSEMBLE
PROBABILITIES.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
AS OF 600 AM SATURDAY...
VFR CONDITIONS ARE EXPECTED ACROSS CENTRAL NC THROUGH THE TAF
PERIOD. THE ARCTIC COLD FRONT HAS PUSHED WELL EAST OF THE AREA THIS
MORNING, LEAVING FAIR SKIES AND DRY CONDITIONS AS COLDER HIGH
PRESSURE BEGINS TO MOVE IN. CLOUDS WILL CONSIST OF A FEW HIGH-BASED
STRATOCU AND PATCHY MID AND HIGH CLOUDS AT MOST THROUGH TONIGHT.
SURFACE WINDS WILL STAY OUT OF THE NNW OR N, MOSTLY UNDER 10 KTS
EARLY THIS MORNING AND TONIGHT, AND AROUND 10-15 KTS WITH GUSTS
AROUND 20 KTS TODAY FROM ABOUT 14Z TO 22Z.
LOOKING BEYOND 12Z SAT, VFR CONDITIONS WILL LARGELY PREVAIL THROUGH
WED UNDER COLD HIGH PRESSURE. A BRIEF PERIOD OF LIGHT SHOWERS AND
SUB-VFR CIGS MAY OCCUR LATE TUE INTO EARLY WED, MAINLY IN THE SE,
BUT CONFIDENCE IS LOW. -GIH
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...KREN
AVIATION...HARTFIELD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page