293
FXUS62 KRAH 170531 RRA
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1230 AM EST SUN, NOV 17 2024
SYNOPSIS
HIGH PRESSURE WILL BUILD ACROSS THE MIDDLE AND SOUTH ATLANTIC STATES
THROUGH MONDAY, THEN MOVE OFFSHORE MONDAY NIGHT. A STRONG COLD FRONT
WILL MOVE THROUGH THE REGION MID-WEEK.
NEAR TERM /TONIGHT/
AS OF 905 PM SATURDAY...
* FROST ADVISORY EXPANDED ACROSS THE REST OF THE (CLIMATOLOGICALLY-
FAVORED) PIEDMONT AND INTO THE NORTHWESTERN SANDHILLS AND CENTRAL
COASTAL PLAIN
IN THE MID/UPPER-LEVELS, A HIGH AMPLITUDE RIDGE EVIDENT IN 00Z UPPER
AIR CHARTS FROM THE CNTL GULF OF MEXICO TO ERN ON WILL PROGRESS
SLOWLY EWD ACROSS THE SOUTHEAST AND MIDDLE ATLANTIC TONIGHT. DEEP
SUBSIDENCE WILL RESULT WITHIN AN ALREADY DEEPLY DRY PROFILE DEPICTED
IN THE 00Z-OBSERVED GSO AND RNK SOUNDINGS, WHERE PWS OF AROUND A
QUARTER INCH WERE MEASURED. FARTHER UPSTREAM, MAINLY THIN, HIGH-
LEVEL MOISTURE EVIDENT IN BOTH SATELLITE AND OBSERVED SOUNDING DATA
OVER THE OH VALLEY AND UPR MIDWEST WILL STREAM SEWD AND ACROSS CNTL
NC SUNDAY MORNING.
AT THE SURFACE, A RIDGE, SURROUNDING PACIFIC HIGH PRESSURE NOW
CENTERED AT 1023 MB OVER THE LWR GREAT LAKES AND EXTENDING
THROUGHOUT THE SOUTHEAST AND NRN GULF OF MEXICO, WILL BECOME
CENTERED OVER THE MIDDLE AND SOUTH ATLANTIC (FROM PA TO NC) BY
SUNDAY MORNING. ASSOCIATED CALM HAS ALREADY BECOME ESTABLISHED
ACROSS CNTL NC THIS EVENING AND WILL CONTINUE THROUGHOUT THE NIGHT
AND EARLY TO MID-MORNING SUNDAY.
THE COMBINATION OF CALM AND CLEAR, ASIDE FROM THE AFOREMENTIONED
HIGH CLOUDS SUNDAY MORNING, WILL FAVOR EXCELLENT RADIATIONAL COOLING.
GIVEN THAT TEMPERATURES AWAY FROM URBAN AREAS REACHED THE 30S THIS
PAST (SAT) MORNING OVER ALL BUT PARTS OF THE COASTAL PLAIN AND
SANDHILLS (SEE THE LATEST PUBLIC INFORMATION STATEMENT - PNSRAH),
TEMPERATURES WITH MORE-PROLONGED AND IDEAL RADIATIONAL COOLING
TONIGHT SHOULD BE EVEN LOWER AND SUPPORTIVE OF FROST IN MOST ALL OF
RURAL, CNTL NC. THE FROST ADVISORY WAS CONSEQUENTLY EXPANDED TO
INCLUDE ALL BUT THE SRN COASTAL PLAIN AND ERN SANDHILLS. EVEN THE
TYPICALLY COLDER LOCATIONS OF THE LATTER COUNTIES MAY EXPERIENCE
PATCHY FROST SUNDAY MORNING.
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 /06Z SUNDAY THROUGH THURSDAY/
AS OF 1230 AM SUNDAY...
VFR CONDITIONS EXPECTED AT ALL SITES THROUGH THE PERIOD. HIGH
PRESSURE OVERHEAD WILL ALLOW FOR CALM (OR NEARLY CALM) WINDS THROUGH
THE OVERNIGHT HOURS. A LIGHT SW SURFACE FLOW UNDER 10KT IS EXPECTED
SUNDAY AFTERNOON.
OUTLOOK: VFR WEATHER EXPECTED SUNDAY NIGHT THROUGH MONDAY. A STRONG
COLD FRONT MOVING THROUGH THE REGION ON TUESDAY AND TUESDAY NIGHT
WITH A PERIOD OF SUB-VFR CONDITIONS WITH SHOWERS/GUSTY WINDS.
RAH WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 4 AM TO 8 AM EST SUNDAY FOR NCZ007>011-021>028-
038>043-073>078-083-084.
SYNOPSIS...BADGETT/MWS
NEAR TERM...MWS
SHORT TERM...KC
LONG TERM...LUCHETTI
AVIATION...BADGETT
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