Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 281748 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 148 PM EDT FRI AUG 28 2015 .SYNOPSIS...A FRONTAL ZONE WILL HOLD JUST OFF THE NORTH CAROLINA COAST THROUGH THE WEEKEND... WHILE HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. && .NEAR TERM /THROUGH TONIGHT/... AS OF 957 AM FRIDAY... AREA IS UNDER A QUASI-ZONAL FLOW ALOFT... WHILE A WEAK UPPER LEVEL LOW HAS DEVELOPED OVER THE NORTHERN GULF. AT THE SURFACE... HIGH PRESSURE OVER THE MIDATLANTIC IS EXTENDING IN TO THE AREA. EXPECT A DRY AND MOSTLY SUNNY DAY WITH A DRY AIRMASS... PW UNDER AN INCH... ACROSS THE AREA. DRY ADIABATIC MIXING YIELDS HIGHS IN THE MID TO UPPER 80S. LOWS TONIGHT IN THE LOWER 60S. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 305 AM FRIDAY... DRY WEATHER LOOKS LIKELY TO CONTINUE... ALTHOUGH WE SHOULD SEE THICKENING CLOUD COVER ESPECIALLY SAT NIGHT WITH A SLIGHT RECOVERY IN HUMIDITY. THE SURFACE HIGH TO OUR NORTH WILL SLIP EASTWARD OFF THE MIDATLANTIC COAST AND WEAKEN... ALTHOUGH A WEAK MODIFIED SOUTHERN PORTION OF THIS RIDGE WILL BREAK OFF AND SETTLE OVER THE SRN APPALACHIANS AND ADJACENT PIEDMONT THROUGH SAT NIGHT... KEEPING THE LOW LEVELS FAIRLY DRY. PW VALUES ARE PROJECTED TO STAY AOB 1 INCH INTO SAT EVENING... ALTHOUGH SW SECTIONS OF THE CWA WILL SEE PW HEAD BACK UP TOWARD 1.25-1.5 INCHES AS MOISTURE SURGES BACK INLAND ACROSS GA AND SC INTO AL AND SW NC. THIS WILL OCCUR AHEAD OF A WEAK MID LEVEL LOW THAT WILL LIFT NORTHWARD FROM THE NORTH CENTRAL GULF THROUGH MS/AL... DRAWING INCREASED DPVA ACROSS GA INTO THE WRN/CENTRAL CAROLINAS. BUT MUCH OF CENTRAL NC WILL HOLD WITHIN A FAIRLY DRY AIR MASS WITH NO TRIGGER TO FORCE ASCENT... AND DESPITE THE GRADUAL INCREASE IN CLOUDS ESPECIALLY OVER THE SOUTH AND WEST LATE SAT INTO SAT NIGHT... WILL KEEP PRECIP CHANCES OUT OF THE FORECAST. HIGHS ONCE AGAIN SHOULD BE IN THE MID 80S TO NEAR 90... PERHAPS A COUPLE OF DEGREES ABOVE TODAY`S HIGHS AS THICKNESSES RISE WHILE STAYING JUST SLIGHTLY BELOW NORMAL. LOWS 63-68 SAT NIGHT WITH A TREND TO PARTLY TO MOSTLY CLOUDY SKIES. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 355 AM FRIDAY... THE MODELS INDICATE THAT A CLOSED LOW CENTERED NEAR THE CENTRAL GULF COAST THIS MORNING WILL EJECT NORTHEASTWARD AS A SHORTWAVE TROUGH THROUGH THE SOUTHERN AND CENTRAL APPALACHIANS SUN-SUN NIGHT...WITH THE PAST COUPLE OF RUNS OF THE ECMWF OUT-PACING THE PREFERRED AMERICAN MODELS BY 6-12 HOURS WITH THE TIMING OF THIS FEATURE. THE ASSOCIATED FORCING FOR ASCENT WILL OVERSPREAD THE WESTERN CAROLINAS DURING PEAK HEATING...OR SHORTLY THEREAFTER WITH NORTHEASTERN EXTENT INTO THE NC SOUTHERN AND WESTERN NC PIEDMONT...WHICH IN CONJUNCTION WITH BOTH GRADUALLY INCREASING DEEP MOISTURE IN SW FLOW AND A WEAKENING CAP ALOFT...SHOULD PROVE SUPPORTIVE OF SCATTERED SHOWERS AND STORMS INVOF THE YADKIN RIVER AND ESPECIALLY WEST/IN THE MOUNTAINS...WHERE LOWER LEVEL FORCING/DIFFERENTIAL HEATING WILL BE MORE LIKELY TO COMPENSATE FOR A STILL RELATIVELY DRY BOUNDARY LAYER CHARACTERIZED BY SFC DEWPOINTS IN THE LOW-MID 60S. SOME OF THIS ACTIVITY COULD LINGER OVERNIGHT OVER THE PIEDMONT...AS THE S/W TROUGH TRACKS INTO WESTERN NC. NEAR CLIMO TEMPERATURES IN THE MID-UPPER 80S AND MID-UPPER 60S. THE MODELS CONTINUE TO SUGGEST ADDITIONAL SHORTWAVE ENERGY WILL AMPLIFY INTO THE SOUTHERN PLAINS TO LOWER-MID MS VALLEY AND EFFECTIVELY CAUSE THE PATTERN ALOFT TO RETROGRADE (DISCONTINUOUSLY)...AND CONSEQUENTLY ALLOW THE SUB-TROPICAL RIDGE BULGE WESTWARD ALONG THE SOUTHEAST US COAST. AT THE SAME TIME...A SEPARATE RIDGE ALOFT IS FORECAST TO BUILD ACROSS THE OH VALLEY AND GREAT LAKES...AND THE RESULT IN RECENT MODEL RUNS IS A SLOWER AND MORE WEST AND SOUTHWARD SUPPRESSED TRACK OF ERIKA. ANY ASSOCIATED TROPICAL MOISTURE OR AFFECTS ON CENTRAL NC WOULD LIKELY NOT OCCUR UNTIL MID-WEEK...AND EVEN THAT WILL BE CONDITIONAL ON 1) ERIKA NOT DISSIPATING ENTIRELY AS IT TRACKS WEST OR NORTHWEST THROUGH A HOSTILE ENVIRONMENT DURING THE NEXT DAY OR TWO...AND 2) THE AFOREMENTIONED BUILDING RIDGE NOT COMPLETELY SUPPRESSING THE SYSTEM --OR WHAT IS LEFT OF IT-- SOUTH AND WEST OF OUR REGION THROUGHOUT THE FORECAST PERIOD. GIVEN THE UNCERTAINTY AND POSSIBLE MINIMAL AFFECT FROM ERIKA...HAVE TRENDED THE FORECAST TOWARD CLIMO FOR THE UPCOMING WEEK...WITH SLIGHT-CHANCE DIURNAL POP AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVG. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 145 PM FRIDAY... 24 HOUR PERIOD: VFR CONDITIONS WILL PREVAIL AS HIGH PRESSURE EXTENDS IN TO THE REGION FROM THE MIDATLANTIC. OUTLOOK: VFR CONDITIONS REMAIN LIKELY. MAINLY DIURNAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE SUNDAY THROUGH MIDWEEK AS MOISTURE INCREASES ACROSS THE AREA.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...30 SHORT TERM...HARTFIELD LONG TERM...26 AVIATION...30

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