327
FXUS62 KRAH 162323
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
623 PM EST SAT NOV 16 2024
SYNOPSIS
HIGH PRESSURE WILL BUILD ACROSS THE MIDDLE AND SOUTH ATLANTIC STATES
THROUGH THE WEEKEND INTO MONDAY, THEN MOVE OFFSHORE MONDAY NIGHT.
NEAR TERM /THROUGH TONIGHT/
AS OF 216 PM SATURDAY...
...RISK OF FROST ACROSS THE NORTHERN PORTIONS OF THE PIEDMONT AND
COASTAL PLAIN AND IN OUTLYING/RURAL AREAS...
UNDERNEATH INCREASING HEIGHTS/SUBSIDENCE ALOFT, SFC HIGH PRESSURE
THAT EXTENDS FROM THE GREAT LAKES SOUTH TO THE GULF COAST WILL SHIFT
EAST OVER THE REGION TONIGHT AND SUNDAY.
EXCELLENT RADIATIONAL COOLING IS EXPECTED THIS EVENING AND FOR MUCH
OF OVERNIGHT HOURS WITH WINDS BECOMING DEAD CALM AS THE SFC RIDGE
AXIS SHIFTS OVERHEAD. WHILE MODELS DO SHOW AN INCREASE IN CIRRUS
LATE, FCST SOUNDINGS SUGGEST THE HIGH CLOUDS WILL EITHER ARRIVE TOO
LATE OR TOO THIN/WISPY TO SIGNIFICANTLY NEGATIVELY IMPACT LOWS
TONIGHT. EXPECT LOWS TO BOTTOM OUT IN THE MID TO UPPER 30S, WITH
SOME LOWER 30S POSSIBLE IN THE COLDER OUTLYING/RURAL AREAS. THESE
TEMPS COMBINED WITH THE WET SOILS FROM THURSDAY'S WIDESPREAD PRECIP
EVENT OF 1-2" ARE EXPECTED TO LEAD TO AREAS OF FROST. AS SUCH HAVE
ISSUED A FROST ADVISORY FOR NORTHERN PORTIONS OF THE PIEDMONT AND
COASTAL PLAIN.
SHORT TERM /SUNDAY AND SUNDAY NIGHT/
AS OF 205 PM SATURDAY...
ALOFT, THE SUB-TROPICAL RIDGE WILL SIT OVER THE SOUTHEAST US THROUGH
SUN NIGHT. A S/W WILL MOVE EWD THROUGH THE OH VALLEY AND NORTHEAST
US SUN NIGHT, CLIPPING THE MID-ATLANTIC/NC ALONG THE WAY. AT THE
SURFACE, HIGH PRESSURE WILL DRIFT SEWD THROUGH THE CAROLINAS TO OVER
THE SOUTHEAST US COAST MON, WITH SURFACE WINDS BECOMING MORE SWLY
OVER CENTRAL NC. AS THE HIGH MOVES OFF THE SOUTHEAST US COAST SUN
NIGHT, A LEE TROUGH WILL SET UP OVER CENTRAL NC AND SURFACE WINDS
COULD BECOME MORE WLY, OR EVEN NWLY THROUGH THE NIGHT, ESPECIALLY
ACROSS THE NORTHWEST. THE WEATHER SHOULD REMAIN DRY THROUGH SUN
NIGHT, WITH SOME INCREASING HIGH CLOUDS AS THE S/W PASSES TO THE
NORTH. AS FOR TEMPERATURES, HIGHS SHOULD RANGE FROM LOW 60S NE TO
UPPER 60S SW. LOWS COULD BE A BIT TRICKIER. LOW-LEVEL THICKNESSES
ARE FORECAST TO BE IN THE 1360-1370 METER RANGE BY 12Z MON AND WINDS
SHOULD GRADUALLY TAPER OFF THROUGH THE NIGHT, BECOMING LIGHT (0-4
KTS) BY 12Z MON. THE POTENTIAL FOR INCREASING HIGH CLOUDS COULD BE
THE LIMITING FACTOR FOR RADIATIONAL COOLING, HOWEVER IF THEY ARE
THINNER OR OF LESS COVERAGE THAN EXPECTED FORECAST LOWS MAY BE TOO
HIGH. ALL THAT SAID, FOR NOW HAVE LOWS FORECAST IN THE LOW TO MID
40S.
LONG TERM /MONDAY THROUGH SATURDAY/
AS OF 146 PM SATURDAY...
NWLY FLOW ALOFT WILL CONTINUE MONDAY AS MID-LEVEL RIDGING AMPLIFIES
OVER THE OHIO VALLEY. FLOW ALOFT WILL TURN MORE ZONAL LATE MONDAY AS
A STRONG UPPER TROUGH BEGINS TO LIFT THROUGH THE CENTRAL US. FLOW
FINALLY TURNS MORE SWLY TUESDAY INTO THURSDAY AS THE UPPER TROUGH
LIFTS ACROSS THE EASTERN SEABOARD. A RE-ENFORCING STRONG UPPER LOW
WILL DIVE INTO THE SOUTHEAST FRIDAY INTO SATURDAY. BEHIND THIS
FEATURE, STRONG NWLY FLOW ALOFT RETURNS THROUGH THE WEEKEND.
AT THE SFC, HIGH PRESSURE WILL LARGELY DOMINATE OVER THE SOUTHEAST
MONDAY BEFORE MOVING OFFSHORE TUESDAY. SLY SFC FLOW WILL GRADUALLY
BECOME MORE ORGANIZED AHEAD OF A COLD FRONT TUESDAY/WEDNESDAY
PROMOTING A WARMING TREND THROUGH EARLY NEXT WEEK. TEMPS WILL
GRADUALLY WARM INTO THE UPPER 60S/LOWER 70S THROUGH MIDDLE OF NEXT
WEEK. CONDITIONS SHOULD REMAIN DRY THROUGH MONDAY. HOWEVER,
ANOMALOUS PWAT WILL TRANSPORT INTO THE AREA TUESDAY, INCREASING RAIN
CHANCES MID-WEEK AHEAD OF THE APPROACHING COLD FRONT.
ENSEMBLES ARE IN A BIT BETTER AGREEMENT WITH THIS SYSTEM COMPARED TO
RECENT DAYS AS FAR AS RAINFALL POTENTIAL. IT STILL APPEARS THAT A
SFC LOW WILL DEVELOP SOMEWHERE TO OUR WEST AND NORTH, PROMOTING
HIGHER RAIN TOTALS IN THESE AREAS. FURTHER SOUTH, MOISTURE
ASSOCIATED WITH THE REMNANTS OF TC SARA WILL LIKELY PLUME UP INTO
THE SOUTHEAST. HOWEVER, GUIDANCE CONTINUES TO PUMP OUT MORE
PRECIPITATION TO OUR SOUTH (WHERE CONVECTION IS MORE LIKELY). THE
EPS IS A BIT MORE BULLISH BRINGING DEEPER MOISTURE INTO OUR AREA,
BUT IT'S LOOKING MORE LIKE AN OUTLIER (THE GEPS IS TRENDING MORE
TOWARDS THE GEFS AS FAR AS SUGGESTING LESS AVAILABLE MOISTURE IN OUR
AREA.) STILL A BIT EARLY TO DISCUSS RAINFALL TOTALS WITH THIS
SYSTEM, BUT IT'S WORTH NOTING THAT EVEN THE 95TH PERCENTILE AMONGST
ENSEMBLE GUIDANCE IS ONLY PUMPING OUT UPWARD OF A HALF INCH OF RAIN
AT THIS TIME. FOR NOW, WILL MAINTAIN MEDIUM TO HIGH CHANCE POPS
PEAKING IN THE TUESDAY NIGHT TO WEDNESDAY NIGHT PERIOD.
RAIN CHANCES SHOULD DIMINISH THURSDAY NIGHT WITH A DRYING TREND
FRIDAY THROUGH THE WEEKEND. ONE CAVEAT TO THIS, HOWEVER, IS THAT
WITH THE PASSAGE OF THE STRONG UPPER LOW/VORT MAX EARLY FRIDAY
THROUGH SATURDAY, MODELS ARE SUGGESTING THE POTENTIAL FOR STRONG MID-
LEVEL LAPSE RATES. FORECAST SOUNDINGS DURING THIS TIME INDICATE SOME
LINGERING LOWER TO MID LEVEL MOISTURE (SOME SATURATION IN THE ICE
GROWTH ZONE), AND LOW FREEZING LEVELS. AS SUCH, WOULD NOT BE
SURPRISED IF THERE ARE ISOLATED REPORTS OF GRAUPEL ESPECIALLY FRIDAY
AFTERNOON.
THE POST-FRONTAL AIR MASS MAY BE QUITE COLD, WITH THE NBM ALREADY
SUGGESTING LOWER TO MID 50S HIGH TEMPERATURES MAY BE POSSIBLE
THURSDAY AND FRIDAY. ADDITIONALLY, ENSEMBLES/FORECAST SOUNDINGS
INDICATE POST-FRONTAL WINDS COULD GET QUITE GUSTY THURSDAY AND
FRIDAY, WITH GUSTS OF UP TO 20 TO 30 MPH POSSIBLE. OVERNIGHT LOWS
LATE THIS WEEK MAY DIP INTO THE MID TO UPPER 30S AS WELL.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
AS OF 623 PM SATURDAY...
VFR CONDITIONS EXPECTED AT ALL SITES THROUGH THE PERIOD. HIGH
PRESSURE OVERHEAD WILL ALLOW FOR CALM (OR NEARLY CALM) WINDS THROUGH
THE OVERNIGHT HOURS, WITH ONLY A FEW KTS EXPECTED OUT OF THE
SOUTHWEST AFTER DAYBREAK SUNDAY. FEW-SCT HIGH CLOUDS WILL OVERSPREAD
THE AREA ON SUNDAY BUT SHOULD BE OF MINIMAL IMPACT.
OUTLOOK: VFR WEATHER EXPECTED SUNDAY NIGHT THROUGH MONDAY. A STRONG
COLD FRONT MOVING THROUGH THE REGION WILL BRING WIDESPREAD RAIN AND
ASSOCIATED SUB-VFR RESTRICTIONS TO THE AREA TUESDAY AND TUESDAY
NIGHT. THE PRECIPITATION WILL MOVE OFFSHORE BETWEEN WED 12-18Z, WITH
A RETURN VFR CONDITIONS DURING THE AFTERNOON. A DEEPENING AREA OF
LOW PRESSURE INVOF THE GREAT LAKES WILL YIELD FREQUENT GUSTS OF 20
TO 25 KTS TO CLOSE OUT THE WEEK.
RAH WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 4 AM TO 8 AM EST SUNDAY FOR NCZ007>011-
023>028.
SYNOPSIS...BADGETT/MWS
NEAR TERM...CBL
SHORT TERM...KC
LONG TERM...LUCHETTI
AVIATION...LEINS/CBL
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