000
FXUS62 KRAH 201821
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
221 PM EDT MON MAY 20 2013

.SYNOPSIS...
A SHORTWAVE TROUGH WILL CONTINUE TO WORK THROUGH THE AREA THIS
AFTERNOON BRINGING UNSETTLED WEATHER THROUGH THIS EVENING. THE
TROUGH WILL MEANDER NORTHEASTWARD TUESDAY BEFORE MORE SETTLED
WEATHER RETURNS FOR WEDNESDAY.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 215 PM MONDAY...

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

TODAY: WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE BROKEN OUT IN A
SERIES OF LINES ACROSS THE CWA THIS AFTERNOON IN ASSOCIATION WITH A
SHORTWAVE IMPULSE PASSING THROUGH SOUTHERN VA. FOR THE MOST
PART...THUNDER HAS BEEN LIMITED TO A SELECT FEW CELLS WITH HEAVY
SHOWERS BEING THE PRIMARY MODE OF CONVECTION. THERE ARE SEVERAL WEAK
BOUNDARIES THAT HAVE SET UP THIS AFTERNOON. THE FIRST HAS LIFTED
NORTHEAST OF THE CWA...A SECOND ALONG THE HIGHWAY 1 CORRIDOR AND A
THIRD THROUGH THE TRIAD JUST EAST OF THE I-85 CORRIDOR. THESE TWO
LINES WILL GRADUALLY PUSH EASTWARD THIS AFTERNOON BRINGING MORE
HEAVY RAIN TO AN AREA ALREADY RECEIVING 2-3 INCHES OF RAIN IN SOME
LOCATIONS. THAT BEING SAID...RAIN RATES HAVE BEEN LOW ENOUGH AND
ENOUGH TIME HAS PASSED SINCE THE LAST RAINFALL THAT FLOODING SHOULD
NOT BE A WIDESPREAD PROBLEM THIS AFTERNOON. MORE LOCALIZED FLOODING
IS POSSIBLE WITH HEAVIER SHOWERS ESPECIALLY IN URBAN AREAS AND IN
THE NORMALLY FLASHY SMALLER CREEKS. RAINFALL TOTALS THIS AFTERNOON
WILL RANGE FROM A TENTH TO A QUARTER OF AN INCH OR SO WITH LOCALLY
HEAVIER AMOUNTS IN STRONGER STORMS. TRAINING OF STORMS SHOULD NOT BE
AS BIG OF A PROBLEM THIS AFTERNOON AND EVENING AS IT WAS EARLIER
THIS MORNING.

DESPITE THE SHORTWAVE ENERGY SEVERE POTENTIAL THIS AFTERNOON STILL
LOOKS EXTREMELY LIMITED. BOTH LOW AND MID-LEVEL LAPSE RATES ARE VERY
WEAK...AS IS THE EFFECTIVE SHEAR WHICH IS LESS THAN 15 KNOTS IN ALL
LOCATIONS. ML CAPE VALUES REMAIN BETWEEN 500-1000...LIMITED BY THE
CONTINUED BROKEN TO OVERCAST SKIES THIS AFTERNOON. THAT BEING SAID A
FEW CELL MERGERS HAVE ALLOWED SOME SHOWERS TO GROW TO A LEVEL
SUPPORTIVE OF VERY SMALL HAIL AND LIGHTNING. OTHERWISE HEAVY RAIN
AND MINOR FLOODING WILL CONTINUE TO BE THE MAIN THREAT OF THE DAY.

EXPECT WINDS THIS AFTERNOON TO GENERALLY BE SOUTHWESTERLY AT 5-10
KNOTS WITH THE OCCASIONAL GUST TO 15-20 KNOTS IN SHOWERS. HIGH
TEMPERATURES TODAY WILL MOST LIKELY VARY DEPENDING ON LOCATION WITH
A FEW BREAKS IN THE CLOUDS SUPPORTIVE OF HIGHS NEAR 80 WITH THOSE
LOCATIONS MAINTAINING OVERCAST SKIES TO TOP OUT IN THE MID TO UPPER
70S.

TONIGHT: HIGH RESOLUTION CONVECTIVE ALLOWING MODELS SUPPORT SHOWER
AND THUNDERSTORM ACTIVITY ENDING IN THE WEST AFTER 00Z AND
CONTINUING THROUGH 3Z IN THE EAST. THE ACCURACY OF THESE
MODELS...ESPECIALLY THE HRRR WAS BETTER EARLIER IN THE DAY THAN IT
IS NOW BUT THE SOLUTION STILL SEEMS REASONABLE GIVEN THE LOCATION OF
THE SHORTWAVE TO THE NORTH. AFTER CONVECTION ENDS EXPECT ISSUES WITH
FOG/LOW CEILINGS AND SUB-VFR VISIBILITIES AT ALL SITES OVERNIGHT.
THIS WILL CONTINUE THROUGH SUNRISE TUESDAY. LOWS WILL BE IN THE
LOWER TO MID 60S NW TO SE.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...

TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.

MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.

TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.

&&


.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 /18Z MONDAY THROUGH FRIDAY/...
AS OF 115 PM MONDAY...

24 HOUR TAF PERIOD:

WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL PREVAIL THIS
AFTERNOON ACROSS THE CWA AT ALL TERMINALS. CURRENTLY RADAR SHOWS
SHORTWAVE CURRENTLY MOVING ACROSS THE TRIAD WITH STRONGER CELLS ON
THE EASTERN SIDE WITH LINGERING SHOWERS TO THE WEST. FOR THE TRIAD
STRONGEST SHOWERS AND THUNDERSTORMS MOST LIKELY MOVING THROUGH NOW
THROUGH THE NEXT COUPLE OF HOURS AND DOWN TRENDING TO MOSTLY LIGHT
SHOWERS THEREAFTER. FURTHER TO THE EAST CONDITIONS SHOULD REMAIN
MORE FAVORABLE FOR HEAVIER SHOWERS AND THUNDERSTORMS THROUGH EARLY
EVENING. EXPECT CEILINGS TO BOUNCE BETWEEN VFR AND MVFR AND SINKING
OCCASIONALLY TO IFR IN THE STRONGER CELLS. WILL COVER THIS WITH A
TEMPO GROUP IN THE TAFS WITH VFR/MVFR PREVAILING. WINDS WILL REMAIN
GENERALLY SOUTHWESTERLY AT 5-10 KNOTS WITH OCCASIONAL GUSTS OF 15-20
IN HEAVY SHOWERS.

AFTER PRECIPITATION WINDS DOWN TONIGHT EXPECT SOME LOW
CEILINGS/VISIBILITIES...GENERALLY AFTER 3Z. EXPECT SOME FOG IN THE
WEST WITH MORE OF A LOW STRATUS SITUATION FURTHER TO THE EAST.
CONDITIONS SHOULD REMAIN SUB VFR EVERYWHERE UNTIL 15Z WHEN VFR
CEILINGS AND VISIBILITIES SHOULD RETURN. ALTHOUGH CONDITIONS WILL BE
IMPROVING AND GENERALLY DRYING...THE MESO-LOW WILL LINGER OVERHEAD
KEEPING THE CHANCE FOR SHOWERS ALIVE THROUGH THE END OF THE TAF
PERIOD.

LONG TERM:

LOW STRATUS AND FOG ARE EXPECTED TO RETURN TUESDAY NIGHT INTO
WEDNESDAY. WEDNESDAY WILL BE THE DRIEST DAY BUT WILL STILL HAVE THE
CHANCE FOR DIURNAL SHOWERS AND STORMS. THURSDAY AND THURSDAY NIGHT
WILL FEATURE THE PASSAGE OF A COLD FRONT AND A RETURN TO SUB-VFR
CONDITIONS. VFR CONDITIONS WILL GRADUALLY RETURN TO THE AREA ON
FRIDAY.

&&

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

&&

$$

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