Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 280139
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
939 PM EDT MON JUL 27 2015

.SYNOPSIS...A SERIES OF PERTURBATIONS ALOFT INTERACTING WITH A MOIST
AND UNSTABLE AIR MASS WILL TRIGGER SCATTERED THUNDERSTORMS...MAINLY
DURING THE AFTERNOON AND EVENING HOURS...THROUGH THE REMAINDER OF
THE WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 925 PM MONDAY...

DIURNALLY INDUCED CONVECTION IS BEGINNING TO DISSIPATE WITH THE
EXCEPTION OF AN AREA OF PERSISTENT RAINFALL IN THE SOUTHWEST
PIEDMONT COINCIDENT WITH TWO CONVERGING SURFACE BOUNDARIES...AIDED
BY SOME DIVERGENCE ALOFT...AS SEEN CLEARLY IN THE WATER VAPOR
IMAGERY. WHILE THIS ACTIVITY COULD PERSIST FOR A LITTLE
WHILE...GENERALLY EXPECT IT TO WEAKEN OVER THE NEXT COUPLE OF HOURS.
WHILE CENTRAL NC REMAINS ON THE BACK/FRONT SIDE OF AN UPPER LEVEL
TROUGH/RIDGE...WATER VAPOR SHOWS ANOTHER SURGE OF DRY AIR ALOFT
MAKING A SOUTHWARD PROGRESSION THROUGH VA AT THIS TIME. TO THE WEST
OF THIS HOWEVER...A STEADY STREAM OF MOISTURE SHOULD CONTINUE TO
FEED INTO THE WESTERN COUNTIES OF THE CWA. HIGH RESOLUTION MODELS
WEAKEN CONVECTION THROUGH THE OVERNIGHT HOURS BUT THE HRRR HOLDS
ONTO SOME RAINFALL IN THE SW PIEDMONT FOR LONGER THAN THE WRF
SIMULATIONS WHICH IS NOT OUT OF THE QUESTION AT THIS POINT. WILL
START TO SEE POCKETS OF FOG AND LOW STRATUS IN RAIN MOISTENED AREAS
AS WELL AS POSSIBLY IN THE EASTERN COUNTIES CLOSER TO SUNRISE. LOW
TEMPERATURES TONIGHT IN THE LOW TO MIDDLE 70S...COOLEST IN THE NE
COUNTIES WHERE UPPER LEVEL CLOUDINESS MAY CEASE ONCE/IF DRY AIR
ALOFT ARRIVES.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 325 PM MONDAY...

A WEAK SFC TROUGH WILL REMAIN STALLED IN VICINITY OF THE WESTERN
PIEDMONT. ALOFT...AN UPPER RIDGE CENTERED OVER THE SOUTHERN PLAINS
BRIEFLY AMPLIFIES INTO THE WESTERN LAKES...VEERING FLOW ALOFT OVER
CENTRAL NC TO A NWLY DIRECTION. WEAK PERTURBATIONS EMBEDDED IN THIS
FLOW ALOFT INTERACTING WITH THE STALLED SFC TROUGH AND AVAILABLE
MOISTURE/INSTABILITY SHOULD TRIGGER SCATTERED CONVECTION...MAINLY IN
THE AFTERNOON AND EVENING HOURS. PROBABILITY OF SCATTERED CONVECTION
APPEARS BEST IN VICINITY OF THE STALLED SFC TROUGH IN THE WESTERN
PIEDMONT...AND IN VICINITY WHERE THE PERTURBATIONS ALOFT TRACK
THROUGH THE REGION. THUS...POPS WILL VARY FROM SOLID
CHANCE(SCATTERED) ACROSS THE NORTHERN PIEDMONT-NORTHERN COASTAL
PLAIN TO SLIGHT CHANCE(ISOLATED)OVER THE FAR SOUTHERN COUNTIES.

BULK OF CONVECTION WILL DIMINISH WITH LOSS OF HEATING TUESDAY
EVENING THOUGH A FEW SHOWERS MAY OCCUR WELL INTO THE NIGHT DUE TO
PERTURBATIONS IN THE NW FLOW ALOFT INTERACTING WITH THE MOISTURE
RICH AIR MASS OVER OUR REGION.

WHILE A STRONG OR SEVERE STORM CANNOT BE RULED OUT TUESDAY
AFTERNOON...BULK OF CONVECTIVE PARAMETERS POINT TOWARD MOST OF THE
STORMS REMAINING BELOW SEVERE CRITERIA.

MAX TEMPS TUESDAY HIGHLY DEPENDENT ON EXTENT OF EARLY MORNING CLOUDS
AND TIMING OF AFTERNOON CONVECTION. FAVORING PARTIAL SUN TO OCCUR
FOR MOST OF THE LATE MORNING-EARLY AFTERNOON...BOOSTING TEMPS WELL
INTO THE 80S-AROUND 90. IF LOW CLOUDS LINGER PAST NOON OR CONVECTION
DEVELOP BY NOON-2 PM...THAN MAX TEMPS MAY END UP BEING 3-5 DEGREES
COOLER THAN FORECAST. MIN TEMPS TUESDAY NIGHT 70-74.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 245 PM MONDAY...

MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT IN SHOWING A MID LEVEL
RIDGE CENTERED ACROSS THE CENTRAL/SOUTHERN PLAINS AND LOWER MS RIVER
VALLEY TO START THE PERIOD (WEDNESDAY)... THEN RETROGRADING IT
WESTWARD ACROSS THE WESTERN U.S. BY LATE WEEK. THE MID LEVEL RIDGE
IS FORECAST TO BUILD NORTH/NORTHWESTWARD AS IT RETROGRADES...
HELPING TO AMPLIFY THE MID/UPPER LEVEL FLOW PATTERN ACROSS THE
CONUS. THIS SHOULD YIELD BROAD MID LEVEL TROUGHING FOR CENTRAL NC
LATE WEEK INTO EARLY NEXT WEEK... WITH A SURFACE COLD FRONT PUSHING
INTO THE AREA FROM THE NORTH AND WEST LATE THURSDAY INTO FRIDAY.
HOWEVER... THE STRONGER FLOW ALOFT WILL REMAIN TO THE NORTH OF
CENTRAL NC... YIELDING GENERALLY WEAK DEEP LAYER SHEAR. QUESTIONS
STILL REMAIN IF THE FRONT WILL PUSH THROUGH THE AREA OR SETTLE
ACROSS SOUTHEASTERN PORTIONS OF CENTRAL NC... AND RESULTANT HOW LONG
PRECIP CHANCES WILL CONTINUE ACROSS CENTRAL NC. FOR NOW WILL TO
TREND THE FORECAST TOWARDS AN UNSETTLED PATTERN FOR LATE THURSDAY
THROUGH SUNDAY... WITH THE POTENTIAL FOR HIGH MOISTURE CONTENT AIR
TO ADVECT INTO THE FROM THE NORTHEASTERN GULF OF MEXICO ALONG WITH
POTENTIALLY A FEW WEAK DISTURBANCES LIFTING NORTH-NORTHEASTWARD AND
ACROSS SOUTH/EASTERN PORTIONS OF THE FA. HOWEVER... DEPENDING ON HOW
FAR SOUTH AND EAST THE BOUNDARY MAKES IT WILL DETERMINE HOW MUCH OF
THE AREA SEE A GOOD CHANCE FOR SHOWERS AND STORMS OVER THE
WEEKEND... ALONG WITH THE POTENTIAL FOR HEAVY RAIN. THUS... WILL
LIMIT POPS TO CHANCE FOR NOW BUT RAISE THEM A BIT... WITH THE
HIGHEST POPS SOUTH/SOUTHEAST THIS WEEKEND.

HIGH TEMPS AHEAD OF THE FRONT ON WEDNESDAY AND THURSDAY ARE EXPECTED
TO BE NEAR NORMAL... GENERALLY AROUND 90 TO THE LOWER TO MID 90S.
HIGH BEHIND THE FRONT WILL GENERALLY BE IN THE MID TO UPPER 80S...
WITH A FEW LOCATIONS TOUCHING THE LOWER 90S... DEPENDING ON THE
PRECIP. LOWS AHEAD OF THE FRONT AREA EXPECTED TO BE IN THE LOWER TO
MID 70S.

&&


.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AS OF 815 PM MONDAY...

LATEST RADAR TRENDS INDICATE BULK OF SHOWER ACTIVITY REMAINS ACROSS
WESTERN NC...INVOF KGSO AND KINT...WITH HI-RES NWP MODELS INDICATING
THE STORMS DIMINISHING BY 03Z.

PER FCST SOUNDINGS AND STATISTICAL GUIDANCE...SOUTHEASTERN AREAS
WILL SEE THE BEST CHANCE OF MORNING LOW CLOUDS/STRATUS...WITH
CEILINGS AT KFAY EXPECTED TO LOWER TO IFR/LIFR. ADDITIONALLY...ANY
AREAS THAT SEE HEAVY RAINFALL THIS EVENING COULD SEE LOCALLY DENSE
FOG.

ANY STRATUS/FOG SHOULD LIFT INTO A BROKEN FLAT CU LAYER BY MID-LATE
MORNING. EXPECT MAINLY DIURNAL SCATTERED SHOWERS AND STORMS AGAIN
TUESDAY AFTERNOON...WITH THE PIEDMONT AIRPORTS(KGSO/KINT/KRDU)ONCE
AGAIN THE FAVORED AREAS.

OUTLOOK: THE PROBABILITY FOR EARLY MORNING FOG AND STRATUS WILL
REMAIN RELATIVELY HIGH THROUGH THE REMAINDER OF THE WEEK. ISOLATED
TO SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE EACH
AFTERNOON/EARLY EVENING...WITH HIGHEST CHANCE POPS IN THE WEST
THROUGH THURSDAY. THE BETTER RAIN CHANCES WILL SHIFT TO EASTERN
AREAS ON FRIDAY AND INTO SATURDAY AS A WEAK SURFACE FRONT COULD
POTENTIALLY STALL NEAR THE COAST.

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...ELLIS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...CBL


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