Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 281046 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 645 AM 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 /TODAY AND TONIGHT/... AS OF 300 AM FRIDAY... HIGH PROBABILITY OF A DRY DAY WITH GENERALLY MOSTLY SUNNY SKIES FOR CENTRAL NC. THE LATEST SURFACE ANALYSIS SHOWS THE FRONTAL ZONE WELL TO OUR SOUTH AND SE... AND THE SURFACE HIGH CENTERED OVER WRN NY/PA NOSING SOUTHWARD INTO CENTRAL NC. THIS CONFIGURATION WILL PERSIST TODAY WITH DEEPLY DRY AIR FILTERING IN... INCLUDING FALLING SURFACE DEWPOINTS DOWN THROUGH THE 50S... AND MUCH BELOW NORMAL PW VALUES. WITH MID LEVEL RIDGING NOSING IN FROM THE SE AND THE LACK OF BOTH FORECAST CAPE AND DEEP LAYER SHEAR... WILL KEEP A DRY FORECAST. HIGH THIN CLOUDS WILL CONTINUE TO STREAM IN ON THE EAST SIDE OF THE WEAK SHEAR AXIS TO OUR WEST... PARTICULARLY EAST OF HIGHWAY 1... BUT MOST AREAS ESPECIALLY WEST SHOULD SEE CONSIDERABLE SUNSHINE TODAY. THICKNESSES AND STATISTICAL GUIDANCE SUPPORT HIGHS IN THE MID-UPPER 80S... VERY CLOSE TO SEASONAL NORMALS. EXPECT FAIR SKIES TONIGHT WITH BELOW-NORMAL LOWS AROUND 60-65. -GIH && .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 /12Z FRIDAY THROUGH TUESDAY/...
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AS OF 645 AM FRIDAY... HIGH CONFIDENCE IN VFR CONDITIONS FOR THE NEXT 24 HOURS AT ALL CENTRAL NC TERMINALS. THE FRONTAL ZONE HAS PUSHED ESE OF THE AREA AS HIGH PRESSURE CENTERED OVER PA/NY BUILDS SOUTHWARD... NOSING INTO CENTRAL NC AND BRINGING LOW LEVEL DRY AIR THAT WILL INHIBIT FORMATION OF ANY FOG/STRATUS THIS MORNING. THE MID LEVEL TROUGH AXIS JUST TO OUR WEST AND THE RESULTING FLOW ALOFT FROM THE S AND SW WILL ALLOW CONSIDERABLE HIGH THIN CLOUDINESS TODAY/TONIGHT... WITH VFR CIGS AOA 20 KFT... ALTHOUGH CIGS WILL START TO LOWER TO AROUND 12-15 KFT TOWARD THE END OF THE TAF VALID PERIOD TONIGHT... AS A WEAK LOW OVER THE NORTH CENTRAL GULF OF MEXICO LIFTS NORTHWARD THROUGH MS/AL INTO TN... BRINGING WEAK DISTURBANCES NORTHWARD INTO NC. LOOKING BEYOND 12Z SAT MORNING: HIGH CONFIDENCE THAT CIGS WILL LOWER BELOW 10 KFT BUT REMAIN VFR THROUGH AT LEAST SUNDAY. AS THE SURFACE HIGH MOVES OFFSHORE... INCREASING MOISTURE MAY BRING A RETURN TO SCATTERED AFTERNOON SHOWERS OR STORMS TUE... BUT OVERALL EXPECT VFR CONDITIONS TO PERSIST INTO MIDWEEK. -GIH
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...26 AVIATION...HARTFIELD

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