National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 201338
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
937 AM EDT MON MAY 20 2013

.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON
TUESDAY REDUCING THE THREAT OF LOCALLY HEAVY RAIN.

&&

.NEAR TERM /TODAY AND TONIGHT/...
-- Changed Discussion --
AS OF 930 AM MONDAY...

...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...

AN UPPER LEVEL MESO-LOW AND ASSOCIATED 500 MB TROUGH WILL LINGER
OVER THE SOUTHEASTERN COASTAL STATES TODAY...WHILE AT THE
SURFACE...RETURN FLOW AROUND A HIGH OF THE MID-ATLANTIC COAST WILL
KEEP LIGHT GRADUAL UPSLOPE FLOW OVER CENTRAL NORTH CAROLINA. CURRENT
RUN OF THE NAM SHOWS GOOD MOISTURE TRANSPORT AND CONVERGENCE OVER
THE CENTRAL AND EASTERN PORTIONS OF THE STATE. CURRENT SPC
MESO-ANALYSIS SHOWS PW VALUES BETWEEN 1.6 AND 1.8 INCHES ACROSS THE
CWA. THIS PATTERN SHOULD HOLD FOR MUCH OF THE DAY AS CURRENT AXIS OF
PRECIPITATION OVER THE CENTRAL PORTION OF THE CWA GRADUALLY MOVES
EASTWARD INTO THE I-95 CORRIDOR. FURTHER TO THE WEST A SHORTWAVE
TROUGH IS EXPECTED TO SWING THROUGH THE WESTERN HALF OF THE STATE
PROVIDING A LITTLE MORE FORCING FOR AFTERNOON SHOWERS AND
THUNDERSTORMS. HRRR MODEL INDICATES THAT SOME HEAVIER SHOWERS WILL
DEVELOP AND MOVE INTO SOUTHWESTERN COUNTIES THIS AFTERNOON. MUCH OF
THE CENTRAL PORTION OF THE CWA HAS RECEIVED SIGNIFICANT RAINFALL
OVER THE PAST 24 HOURS BUT RAINFALL RATES HAVE BEEN LOW ENOUGH THAT
ANY FLOODING PROBLEMS HAVE BEEN NON-EXISTENT AT THIS TIME. WE WILL
CONTINUE TO MONITOR URBAN AREAS AND SMALL STREAMS FOR FLOODING
ACTIVITY WITH CONTINUED RAINFALL THIS AFTERNOON.

AT THIS HOUR MUCH OF THE AREA IS OVERCAST...BUT SOME BREAKS IN THE
CLOUDS COULD PROVIDE SOME DIFFERENTIAL HEATING BOUNDARIES THIS
AFTERNOON. WHILE SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL BE
PROBABLE THIS AFTERNOON...THE LIKELIHOOD THAT ANY OF THESE STORMS
BECOMES SEVERE IS RELATIVELY LOW. WHILE THERE IS SOME
INSTABILITY...EFFECTIVE SHEAR IS VIRTUALLY NON-EXISTENT AND LAPSE
RATES ARE MODEST AT BEST. NO DCAPE TO WORK WITH MAKES SEVERE WINDS
VERY UNLIKELY. EXPECT LOWER CEILINGS TO CONTINUE TO PREVAIL THROUGH
THE MORNING AND INTO THE AFTERNOON ALSO HINDERING INSTABILITY.
DESPITE THIS...HIGHS SHOULD STILL REACH NEAR THE 80 DEGREE MARK THIS
AFTERNOON AS SOUTHWESTERLY FLOW AND WARM AIR ADVECTION HELP ELEVATE
HIGHS TODAY. -ELLIS

SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE. -BADGETT
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 250 AM MONDAY...

A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.

&&


.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 AM MONDAY...

UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.

UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.


&&

.AVIATION /12Z MONDAY THROUGH THURSDAY/...
AS OF 736 AM MONDAY...

MOSTLY MVFR CEILINGS WILL PREVAIL FOR THE NEXT SEVERAL HOURS WITH
SOME HEAVIER SHOWERS EXPECTED...ESPECIALLY AT CENTRAL AND EASTERN
TERMINALS WITH SOME IFR/LIFR CEILINGS POSSIBLE IN HEAVIER SHOWERS.
HEAVY SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL MOVE THROUGH
KRDU...KFAY AND IN A COUPLE OF HOURS...KRWI. FOR NOW TRIAD SITES
KINT AND KGSO SHOULD REMAIN DRY FOR THE NEXT SEVERAL HOURS ALTHOUGH
SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE AS THE NEXT SHORTWAVE
PULSE MOVES THROUGH THE WESTERN PART OF THE STATE. AS THE AFTERNOON
PROGRESSES...CONDITIONS SHOULD BEGIN TO IMPROVE AS FAR AS CEILINGS
TO AS LOWER LEVELS OF THE ATMOSPHERE GRADUALLY DRY OUT. STILL PLENTY
OF MOISTURE TO MAINTAIN SHOWERS AND THUNDERSTORMS WELL INTO THE
AFTERNOON AND EVENING HOURS. WINDS TODAY SHOULD REMAIN LIGHT AND
FROM A SOUTHWESTERLY OR SOUTH SOUTHWESTERLY DIRECTION -ELLIS

IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.

LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.

&&

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

&&

$$

SYNOPSIS...BADGETT
NEAR TERM...ELLIS/BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...ELLIS/BADGETT