Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 180348
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1048 PM EST WED DEC 17 2014

.SYNOPSIS...HIGH PRESSURE OVER THE CENTRAL MISSISSIPPI RIVER VALLEY
WILL EXTEND SOUTHEASTWARD INTO THE MID ATLANTIC AND CAROLINAS ON
THURSDAY AND FRIDAY. A LOW PRESSURE SYSTEM WILL DEVELOP ALONG THE
TEXAS COAST ON FRIDAY AND TRACK EAST ALONG THE GULF COAST ON
SATURDAY...THEN MOVE OFFSHORE THE SOUTHEAST COAST SATURDAY NIGHT
INTO SUNDAY.


&&

.NEAR TERM /OVERNIGHT/...
AS OF 1045 PM WEDNESDAY...

THE LATEST SATELLITE IMAGERY AND RAPID REFRESH MODEL DATA INDICATE
THAT SMALL AMPLITUDE WAVES EMBEDDED IN WESTERLY FLOW ALOFT (IN
CENTRAL/WESTERN TN AT 02Z) WILL TRAVERSE THE REGION OVERNIGHT.
MEANWHILE...A SFC-925 MB TROUGH EXTENDING SOUTHWESTWARD FROM THE MID-
ATLANTIC INTO THE CAROLINAS THIS EVENING WILL SHIFT OFFSHORE THE
SOUTHEAST COAST BY 12Z THU AS 1028 MB HIGH PRESSURE (CENTERED OVER
IL AT 02Z) EXTENDS EAST/SE THROUGH THE OH VALLEY INTO VA/NC. THOUGH
THE LOWER LEVELS WILL REMAIN DRY...MID/UPPER LEVEL MOISTENING (AS
EVIDENCED BY 12/00Z GSO RAOB DATA) WILL PERSIST OVERNIGHT AS
MOISTURE ADVECTS DOWNSTREAM OF PRECIP ASSOC/W A SHORTWAVE TRACKING
EASTWARD FROM THE CENTRAL PLAINS TO THE CENTRAL MS RIVER VALLEY.
THIS WILL DO LITTLE TO ALTER THE DRY/STABLE AIRMASS CURRENTLY IN
PLACE ACROSS THE CAROLINAS...HOWEVER...GIVEN THE DRY ANTECEDENT
AIRMASS CURRENTLY IN PLACE AND THE ABSENCE OF LOW-LEVEL WARM
ADVECTION.

WITH THE ABOVE IN MIND...EXPECT CONTINUED DRY CONDITIONS AND
ABSOLUTELY NO CHANCE FOR PRECIPITATION. GIVEN THE ONGOING/ CONTINUED
INFLUX OF CIRRUS (CEILINGS ~25 KFT) FROM THE WEST...THE PRIMARY
FORECAST CONCERN WILL BE THE `DEGREE` TO WHICH UPPER LEVEL CEILINGS
ATTENUATE RADIATIONAL COOLING...AND THE IMPACT THEREOF ON LOW
TEMPERATURES. WITH TEMPS RANGING FROM THE MID 30S TO LOWER 40S PER
02-03Z OBSERVATIONS...EXPECT OVERNIGHT LOWS IN THE 30S EVERYWHERE...
LOWER 30S WHERE CIRRUS IS LESS OPAQUE/THINNER AND MID 30S WHERE
CIRRUS IS THICKER. CIRRUS...LATIN FOR `CURL`...ARE HIGH ALTITUDE
CLOUDS COMPOSED ENTIRELY OF ICE CRYSTALS WHICH...WHEN PRESENT AT
NIGHT UNDER MOONLIGHT (OPTIMALLY A FULL MOON)...PLAY A KEY ROLE IN
THE FORMATION OF AN OPTICAL PHENOMENON KNOWN AS THE 22 DEGREE HALO
OR `MOON HALO`. MOON HALO ENTHUSIASTS MAY ULTIMATELY BE
DISAPPOINTED...HOWEVER...DUE TO AN ILL-FATED JUXTAPOSITION WITH THE
WANING CRESCENT PHASE IN WHICH <20% OF MOON LIGHT WILL BE PRESENT IN
COMPARISON WITH THAT OF A FULL MOON (CITATION NEEDED). -VINCENT

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 215 PM WEDNESDAY...

MID LEVEL RIDGE AXIS APPROACHES EARLY ON THURSDAY AND GIVES WAY TO A
SOUTHERN STREAM SHORTWAVE TROUGH THAT SLIDES BY ACROSS THE OH VALLEY
AND THE MID ATLANTIC THURSDAY NIGHT. EXPECT FAIR WEATHER DURING THE
PERIOD WITH A FAIRLY THICK VEIL OF HIGH AND ESPECIALLY MID LEVEL
CLOUDINESS. GUIDANCE...ESPECIALLY THE GFS HAS BEEN HINTING AT SOME
LIGHT PRECIP MAKING IT ACROSS THE MOUNTAINS INTO THE WESTERN
PIEDMONT ON THURSDAY. RECENT RUNS HAVE BACKED OFF THIS AND WE EXPECT
A DRY PERIOD AND HAVE LOWERED POPS. WITH A GOOD DEAL OF CLOUD
COVER...HIGHS ON THURSDAY WILL SLOWLY REACH THE 48 TO 55 RANGE. LOOK
FOR LESS VARIABILITY IN LOWS ON THURSDAY NIGHT WITH LINGER MID AND
HIGH CLOUDS...LOWS SHOULD RANGE BETWEEN 32 AND 36 DEGREES. -BLAES
&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 254 PM WEDNESDAY...

SURFACE HIGH PRESSURE ACROSS THE GREAT LAKES WILL EXTEND IN TO THE
AREA... WHILE WE REMAIN UNDER CONFLUENT FLOW ALOFT. A SOUTHERN
STREAM SHORTWAVE OVER THE SOUTHERN PLAINS ON FRIDAY WILL LIFT
NORTHEASTWARD INTO THE OHIO VALLEY ON SATURDAY. SURFACE LOW PRESSURE
WILL DEVELOP ALONG THE NORTHERN GOM LATE FRIDAY.. AND MOVE OFF THE
SOUTHEAST COAST ON SUNDAY. THIS SYSTEM WILL BEGIN TO SPREAD RAIN IN
TO THE REGION BY DAYBREAK SATURDAY... AND RAIN WILL REMAIN ACROSS
THE AREA THROUGH THE EVENING BEFORE TAPERING OFF FROM WEST TO EAST
SUNDAY MORNING. RAIN STILL LOOKS TO BE THE MAIN PRECIP TYPE...
HOWEVER THERE CONTINUES BE THE POSSIBILITY OF FEW WET SNOWFLAKES
MIXING IN ACROSS THE TYPICAL NORTHWEST PIEDMONT AREA. TEMPERATURES
WILL BE BELOW NORMAL ON SATURDAY AND SUNDAY.

WEAK HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE AREA MONDAY...
AND CLOUDS AND BELOW NORMAL TEMPERATURES WILL CONTINUE WITH LOW
LEVEL NORTHEASTERLY FLOW. MODELS BRING A STRONG SHORTWAVE INTO THE
CENTRAL US ON TUESDAY... AND DIG A DEEP TROUGH ACROSS THE PLAINS AS
FLOW BECOMES HIGHLY AMPLIFIED. AS THIS SYSTEM MOVES EASTWARD...
UNSETTLED CONDITIONS LOOK LIKELY MIDWEEK.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 615 PM WEDNESDAY...

24-HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS AND LIGHT
YET VARIABLE WINDS WILL DOMINATE THE 24 HOUR TAF PERIOD AS HIGH
PRESSURE RIDGES IN. SCATTERED TO BROKEN HIGH CLOUDS WILL CONTINUE TO
MOVE OVER THE AREA FROM THE WEST AND REMAIN IN PLACE THROUGH
THURSDAY. -KC

LOOKING AHEAD: VFR CONDITIONS WILL HOLD THROUGH FRI EVENING WITH
PERIODS OF MID AND HIGH CLOUDS AND VFR VSBYS...BUT POOR AVIATION
CONDITIONS ARE EXPECTED FROM SAT THROUGH MON. A STORM SYSTEM WILL
FORM OVER THE TEXAS GULF COAST LATE FRIDAY...WITH LOW PRESSURE
STRENGTHENING AS IT TRACKS EAST ACROSS THE SOUTHERN GULF STATES
SATURDAY...TO ALONG OR JUST OFF THE SOUTHEAST COAST SAT NIGHT AND
SUN. WIDESPREAD RAIN WITH SUB-VFR CONDITIONS APPEAR LIKELY FROM
EARLY SAT MORNING (POTENTIALLY BEFORE DAYBREAK) THROUGH SAT. RAIN
WILL TAPER TO PATCHY LIGHT DRIZZLE FOR SAT NIGHT THROUGH AT LEAST
SUN NIGHT WITH SUB-VFR CONDITIONS PERSISTING. LOW CIGS COULD HOLD
THROUGH MON AS WELL. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BLAES
LONG TERM...SEC
AVIATION...KC/HARTFIELD



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.