Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 011935
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
335 PM EDT SUN MAY 1 2016

.SYNOPSIS...
A SERIES OF UPPER LEVEL DISTURBANCES WILL INTERACT WITH A MOIST AND
UNSTABLE AIR MASS OVER CENTRAL NC TO TRIGGER SCATTERED CONVECTION
THROUGH WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 335 PM SUNDAY...

SUBSIDENCE BEHIND AN EXITING MCV HAS SUPPRESSED ADDITIONAL AFTERNOON
CONVECTION THUS FAR ACROSS CENTRAL NC. STILL EXPECT SCATTERED
CONVECTION TO DEVELOP OVER THE PIEDMONT AND SANDHILLS WITHIN THE 21Z-
00Z TIME FRAME AS WEAK VORTICES ALOFT INTERACT WITH AVAILABLE
MOISTURE AND INSTABILITY. EXPECT BULK OF STORMS TO REMAIN BELOW
SEVERE CRITERIA THOUGH AN ISOLATED STRONG/DAMAGING WIND GUSTS CANNOT
BE RULED OUT. A SHEAR AXIS PROJECTED TO DROP SEWD OUT OF THE CENTRAL
APPALACHIANS AND CROSS VA OVERNIGHT MAY TRIGGER A FEW SHOWERS ACROSS
THE NORTHERN PIEDMONT OVERNIGHT. OTHERWISE EXPECT LOW CLOUDS TO
REDEVELOP OVER MOST OF CENTRAL NC OVERNIGHT. MIN TEMPS LOW-MID 60S.


&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 335 PM SUNDAY...

ANOTHER MCV ASSOCIATED WITH THE CONVECTION NOW OCCURRING OVER
SECTIONS OF THE LOWER MS VALLEY THIS AFTERNOON HAS THE POTENTIAL TO
ENHANCE OUR CONVECTIVE PROBABILITIES ACROSS CENTRAL NC MONDAY AND
MONDAY NIGHT. A LOW LEVEL JET ON THE ORDER OF 30-35KTS EXPECTED TO
DEVELOP LATE IN THE DAY WHILE MID LEVEL LAPSE RATES WILL BE ON THE
ORDER OF 6-7 DEG C/KM. IN ADDITION...CENTRAL NC SEE INCREASING
DIVERGENCE ALOFT MONDAY AS WE BECOME UNDERNEATH THE RIGHT ENTRANCE
REGION OF A 110+KT JET. THESE DYNAMICS SHOULD PROVIDE PLENTY OF LIFT
OF A VERY MOIST AIR MASS (PRECIP WATER VALUES 1.5-1.7 INCHES OF >200
PERCENT OF NORMAL). THUS... SHOULD SEE SCATTERED TO NUMEROUS SHOWERS
AND STORMS ERUPT...MAINLY DURING THE AFTERNOON AND CONTINUING WELL
INTO MONDAY NIGHT. WHILE SEVERE PARAMETERS ARE MARGINAL...POTENTIAL
WILL EXIST FOR LOCALIZED DAMAGING WIND GUSTS AND HAIL TO THE SIZE OF
QUARTERS.  MAIN CONCERN IS A HEAVY RAIN/FLASH FLOOD THREAT AS
TRAINING CELLS OVER URBAN LOCATIONS COULD QUICKLY LEAD TO FLOODING
OF STREETS AS WELL AS CREEKS/STREAMS. DO NOT BELIEVE THAT AREAL
COVERAGE WILL BE ENOUGH TO WARRANT A FLASH FLOOD WATCH THOUGH COULD
SEE THE NEEDED FOR A FEW URBAN/SMALL STREAM STATEMENTS AND POSSIBLY
A FFW OR TWO.

IF THE MCV RESPONSIBLE FOR THE DEEP SOUTH CONVECTION ARRIVES PRIOR
TO 15Z...INITIATING SCATTERED CONVECTION SOONER THAN EXPECTED...THEN
SEVERE WEATHER THREAT WILL BE GREATLY DIMINISHED BUT COULD SEE AN
INCREASE THREAT FOR FLASH FLOODING.

HIGH TEMPS MONDAY DEPENDENT ON PARTIAL SUN OCCURRING IN THE EARLY-
MID AFTERNOON HOURS. IF CLOUDS SLOW TO DEPART OR SCATTERED
CONVECTION COMMENCES SOONER THAN 20Z...THEN HIGH TEMPS MAY END UP
BEING 3-4 DEGREES COOLER. MAX TEMPS 80-85. MIN TEMPS MONDAY NIGHT
LOW-MID 60S.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 258 PM SUNDAY...

A SERIES OF DISTURBANCES IN THE SW FLOW ALOFT WILL MOVE ACROSS THE
CAROLINAS EARLY ON TUESDAY...WITH THE SFC COLD FRONT NOW PROGGED TO
MOVE ACROSS OUR AREA AROUND MID-DAY. UNTIL FROPA...LOOK FOR RAIN
CHANCES TO CONTINUE...THUS AREAS FROM THE TRIANGLE EASTWARD...AND
PARTICULARLY DURING THE FIRST HALF OF THE DAY...SHOULD HAVE THE BEST
CHANCE OF SEEING SHOWERS AND TSTMS. IN THE WAKE OF THE FRONT...LOOK
FOR DRIER NW FLOW TO OVERSPREAD OUR CWA...RESULTING IN DRY WEATHER
FOR THE SECOND HALF OF THE DAY.  FAIR WEATHER WILL THEN CONTINUE
TUESDAY NIGHT AND WEDNESDAY...UNTIL A FAIRLY DEEP CLOSED LOW...
DROPPING SOUTH ACROSS THE GREAT LAKES...PUSHES ANOTHER COLD FRONT
ACROSS OUR AREA WEDNESDAY NIGHT. WORTH NOTING THOUGH...THIS
FRONT...AND THE AIRMASS JUST AHEAD OF IT...APPEARS TO HAVE LIMITED
MOISTURE...RIGHT NOW WE`RE EXPECTING VERY MODEST RAINFALL AMOUNTS
WITH THIS SYSTEM.

IN THE WAKE OF THE FRONT...COOL NW FLOW WILL SET UP OVER OUR AREA
WITH THE UPPER LOW NOW PROGGED TO TRANSIT VA AND NC.  GIVEN THE THE
ASSOC INSTABILITY...SCATTERED SHOWERS AND PERHAPS A TSTM OR TWO WILL
REMAIN POSSIBLE THURSDAY AND FRIDAY. AS IT APPEARS RIGHT NOW...THE
UPPER LOW IS PROGGED TO EXIT TO OUR EAST LATE FRIDAY...WITH
SUBSIDENCE IN THE WAKE OF THIS FEATURE PROVIDING FAIR WEATHER FOR
THE WEEKEND.

TEMPS WILL BE WITHIN A FEW DEG OF NORMAL THROUGH THE WEEK...WITH THE
EXCEPTION OF THURSDAY AND FRIDAY...WHEN TEMPS WILL RUN ABOUT 5-10
DEG BELOW NORMAL.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 200 PM SUNDAY...

CEILINGS WILL CONTINUE TO GRADUALLY LIFT THROUGH THE REMAINDER OF
THE AFTERNOON WITH MOST SITES EITHER HIGH END MVFR OR VFR CONDITIONS
BY 21Z-22. AREAS OF SHOWERS WITH EMBEDDED THUNDERSTORMS WILL EXIT
OUR COASTAL PLAIN COUNTIES BY 19Z. AFTER 20Z...COULD SEE RANDOM
SHOWERS AND ISOLATED T-STORMS DEVELOP OVER THE PIEDMONT THOUGH
COVERAGE EXPECTED TO BE LIMITED. BEST PROSPECTS ARE IN VICINITY OF
THE TRIAD TERMINALS SO WILL HAVE A TEMPO FOR CONVECTION AT THOSE
SITES.

LATER TONIGHT...WIDESPREAD IFR/LIFR CEILINGS WILL DEVELOP AND
PERSIST INTO MONDAY MORNING. POTENTIAL FOR A FEW SHOWERS TO SKIRT
NEAR OR NORTH OF THE TRIAD TERMINALS AS WELL AS KRDU AND KRWI.

LOW CLOUDS EXPECT TO LIFT BY MID DAY. WITH INCREASING
SUNSHINE...ATMOSPHERE WILL DESTABILIZE...LEADING TO THE DEVELOPMENT
OF SCATTERED-NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. A FEW
STORMS MAY BE STRONG-SEVERE BETWEEN 21Z-04Z. IN ADDITION...BLINDING
HEAVY RAIN EXPECTED WITH THE HEAVIER SHOWERS/STORMS.

AN UNSETTLED WEATHER PATTERN TUESDAY THROUGH THURSDAY IS EXPECTED TO
RESULT IN VARIABLE AVIATION CONDITIONS. IT IS HIGHLY PROBABLE THAT
PERIODS OF MVFR/IFR PARAMETERS WILL OCCUR DUE TO CEILINGS...IN
ADDITION TO SCATTERED CONVECTION. IMPROVING AVIATION CONDITIONS
EXPECTED BY LATE IN THE WORK WEEK.

&&

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

&&

$$
SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...RAH
AVIATION...WSS


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