418
FXUS62 KRAH 171816
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
115 PM EST SUN NOV 17 2024
SYNOPSIS
HIGH PRESSURE WILL REMAIN 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 930 AM SUNDAY...
..MILD AND MAINLY SUNNY THIS AFTERNOON
TODAY: AFTER A CHILLY START, THE ONSET OF LIGHT SOUTHERLY FLOW LATER
THIS AFTERNOON WILL RESULT IN MODEST 2-4 DEGREE OF WARMTH FROM
YESTERDAY. WE'LL SEE INTERVALS OF MOSTLY THIN CIRRUS OVERSPILLING
THE RIDGE WITH MOSTLY SUNNY SKIES PREVAILING. AFTER HIGHS RANGING
FROM MID 60S NORTH TO UPPER 60S/NEAR 70 SOUTH.
TONIGHT: THE FORECAST PROBLEM OF THE DAY IS WHETHER OR NOT FOG
DEVELOPS TONIGHT/EARLY MONDAY MORNING. EMPLOYING THE CROSSOVER
TEMPERATURE TECHNIQUE WOULD SUGGEST AREAS OF FOG ARE POSSIBLE ACROSS
THE AREA, WITH HREF AND SREF ENSEMBLE PROBABILITIES MAXIMIZED ACROSS
THE SW PIEDMONT. OTHERWISE, IT WON'T BE AS CHILLY, WITH LOWS
GENERALLY IN THE 40S.
SHORT TERM /MONDAY AND MONDAY NIGHT/
AS OF 212 AM SUNDAY...
ABOVE NORMAL TEMPERATURES RETURN MONDAY AND MONDAY NIGHT (TEMPS 5-10
DEGREES ABOVE NORMAL).
SURFACE HIGH PRESSURE WILL SLIDE JUST TO OUR SOUTH ON MONDAY. THE H5
RIDGE AXIS WILL REMAIN JUST WEST OF OUR REGION INTO MONDAY NIGHT.
ONLY A FEW HIGH CLOUDS ARE EXPECTED TO TOP THE RIDGE AXIS AT TIMES.
WITH RIDGING REMAINING OVERHEAD, EXPECT LIGHT AND VARIABLE WINDS
WITH PARTLY TO MOSTLY SUNNY SKIES. HIGHS WILL MODERATE INTO THE
LOWER 70S REGION WIDE. SKIES SHOULD BE PARTLY CLOUDY MONDAY NIGHT
WITH LOWS IN THE 43-48 RANGE.
LONG TERM /TUESDAY THROUGH SATURDAY/
AS OF 238 AM SUNDAY...
RIDGING OVER THE AREA TUE AND WED AHEAD OF A STRONG TROUGH TRACKING
INTO THE OH VALLEY WILL SPELL OUT MILD HIGHS TO START THE EXTENDED.
HIGHS ON TUE AND WED ARE STILL PROGGED TO BE IN THE UPPER 60S TO LOW
70S, ABOUT 8-10 DEGREES ABOVE NORMAL.
WE CONTINUE TO WATCH FOR THE CHANCE OF PRECIPITATION IN THE LATE TUE
THROUGH WED TIME FRAME. MOST DETERMINISTIC AND ENSEMBLE GUIDANCE
SHOWS LIGHT BUT MEASURABLE RAINFALL TUE NIGHT AS DEEP MOISTURE FROM
REMNANT TC SARA ADVECTS INTO THE SE US. PW'S REACH OVER 250-PERCENT
OF NORMAL AROUND 1.5 INCHES DURING THIS TIME. LIFT IS NOT OVERLY
IMPRESSIVE, DRIVEN LARGELY BY SOME WEAK ISENTROPIC ASCENT IN THE 700-
500 MB LAYER. THE PRIOR GEFS WAS A DRIER OUTLIER COMPARED TO THE 12Z
EPS/GEPS, BUT APPEARS A SMIDGE WETTER IN LINE WITH THE LATEST 00Z
GUIDANCE. EVEN WITH THAT, AMOUNTS ARE ABOUT A TENTH OF AN INCH OR
LESS.
A SECOND CHANCE OF PRECIPITATION, IN THE FORM OF SHOWERS, WILL THEN
BE POSSIBLE WED INTO LATE WED NIGHT, AS A STRONG TROUGH OVER THE MS
VALLEY TRACKS INTO THE OH VALLEY. A STRONG COLD FRONT WILL ACCOMPANY
THIS SYSTEM, MOVING THROUGH LATE WED NIGHT. SOME MORNING LIGHT RAIN
IS POSSIBLE WITH LINGERING ISENTROPIC ASCENT. A SECOND BATCH OF
SHOWERS ARE THEN POSSIBLE WED AFTN INTO THE LATE EVENING AS GUIDANCE
SHOWS PERHAPS AN AREA OF LOW PRESSURE TRACKING ALONG THE FRONT.
THERE ARE SOME SUBTLE DIFFERENCES IN THE LOCATION OF THE TROUGH,
WITH THE ECMWF/CMC WETTER AND FURTHER SOUTH THAN THE GFS. THERE
MIGHT BE A VERY SHORT WINDOW WHERE SOME ISOLATED STORMS COULD FORM
AHEAD OF THE FRONT GIVEN STRONG SHEAR, THOUGH INSTABILITY STILL
APPEARS LIMITED. TOTAL PRECIPITATION AMOUNTS ARE ABOUT A QUARTER
INCH, GIVE OR TAKE IN EITHER DIRECTION.
BEHIND THE FRONT, BRISK WSW TO WNW WINDS WILL BE IN PLACE THU
THROUGH SAT AS THE TROUGH OVER THE REGION SLOWLY LIFTS INTO THE NE
US. SUSTAINED WINDS OF 10-15 COULD GUSTS BETWEEN 25-35 MPH. HIGHS
WILL BE MUCH COOLER AND BELOW NORMAL IN THE LOW TO MID/UPPER 50S
THU/FRI, WITH SOME SLIGHT MODERATION IN THE MID 50S TO AROUND 60 BY
SAT. LOWS WILL BE NEAR NORMAL IN THE MID/UPPER 30S DUE TO PERSISTENT
STIRRING. IN REGARDS TO THE UPPER-TROUGH LATE THU THROUGH FRI, THE
ECMWF/CMC SHOW A RATHER IMPRESSIVE VORT MAX ROTATING THROUGH, WHICH
COULD PRODUCE SOME SPRINKLES/CLOUDS WITH THE STEEP LAPSE RATES. THE
GFS/GEFS ARE FURTHER NORTH WITH THIS FEATURE, SO STILL ENOUGH SPREAD
IN THE GUIDANCE TO LEAVE THE FORECAST DRY AT THE MOMENT.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
AS OF 115 PM SUNDAY...
FORECASTER CONFIDENCE IS LOWER THAN NORMAL WRT THE DEVELOPMENT OF
GROUND FOG TONIGHT/MORNING MORNING. LAST NIGHT, FOG WAS LARGELY
LIMITED TO FOG PRONE LOCATIONS LIKE KRWI. HOWEVER, THERE IS A SIGNAL
IN THE MODELS OF HIGH PROBABILITIES FOR SUB-VFR RESTRICTIONS ACROSS
THE WESTERN PIEDMONT. AS SUCH, INTRODUCED A PREVAILING GROUP FOR SUB-
VFR RESTRICTIONS AT KINT, KGSO, AND KRWI(PERSISTENCE). AT KFAY AND
KRDU, WILL COVER THE POTENTIAL FOR FOG WITH TEMPO GROUP.
OUTSIDE OF FOG OVERNIGHT, EXPECTED PREDOMINATELY VFR CONDITIONS WITH
INTERVALS OF CIRRUS STREAMING ACROSS THE AREA. LIGHT SW WINDS WILL
BECOME MORE WESTERLY MONDAY.
OUTLOOK: A STRONG COLD FRONT MOVING THROUGH THE REGION WILL BRING
WIDESPREAD RAIN AND ASSOCIATED SUB-VFR RESTRICTIONS TO THE AREA LATE
TUESDAY AND WILL LINGER INTO THE DAY ON WEDNESDAY. VFR CONDITIONS
ARE EXPECTED TO RETURN LATE WEDNESDAY AFTERNOON. A DEEPENING AREA OF
LOW PRESSURE INVOF THE GREAT LAKES WILL YIELD FREQUENT GUSTS OF 20
TO 30 KTS THURSDAY AND AGAIN ON FRIDAY.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BADGETT/MWS
NEAR TERM...CBL
SHORT TERM...BADGETT
LONG TERM...KREN
AVIATION...CBL
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