Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 210256 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1056 PM EDT MON APR 20 2015 .SYNOPSIS...
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A COLD FRONT WILL TRACK EAST ACROSS NC TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST LATE TONIGHT THROUGH TUESDAY... THEN SHIFT OFF THE COAST TUESDAY NIGHT INTO WEDNESDAY. A COLD FRONT WILL APPROACH FROM THE NORTH WEDNESDAY NIGHT.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1055 PM MONDAY... ALTHOUGH SEVERE THUNDERSTORM WATCH #89 HAS BEEN ALLOWED TO EXPIRE... THERE REMAINS A CONDITIONAL RISK OF ISOLATED SEVERE THUNDERSTORMS THROUGH AROUND 2 AM. STRONG Q-VECTOR CONVERGENCE ASSOCIATED WITH A NEGATIVELY-TILTED TROUGH ALOFT -ONE WHICH WV IMAGERY INDICATES INCLUDES AN IMPULSE OVER NE GA AND A MORE SUBSTANTIAL SHORTWAVE TROUGH OVER THE TN VALLEY...WITH MARKED DRYING IMMEDIATELY BEHIND THE LATTER- WILL CONTINUE TO PIVOT NE ACROSS CENTRAL NC THROUGH 04Z IN THE SOUTHERN AND WESTERN PIEDMONT TO 08Z OVER THE NE PIEDMONT AND COASTAL PLAIN. IN ADDITION...OBJECTIVE ANALYSIS DATA INDICATE A PLUME OF STEEP MID LEVEL LAPSE RATES BETWEEN 7 AND 7.5 C/KM SAMPLED BY THE BMX 00Z RAOB HAS FINALLY ADVECTED INTO CENTRAL NC...SUPPORTIVE OF AN UPTICK IN MLCAPE TO BETWEEN 500-1000 J/KG...DESPITE BOTH NOCTURNAL AND DIABATIC OUTFLOW COOLING. LASTLY...THE SURFACE COLD FRONT WAS ANALYZED AT 02Z OVER THE FOOTHILLS OF THE CAROLINAS...WITH A PRE- FRONTAL TROUGH IMMEDIATELY AHEAD OF THE FRONT; AND THESE FEATURES ARE FORECAST TO MOVE EAST ACROSS CENTRAL NC WITH SIMILAR TIMING AS THE AFOREMENTIONED UPPER FORCING. THE MAIN LIMITING FACTOR WITH ANY APPRECIABLE CONVECTIVE REDEVELOPMENT WILL BE DEEP MOISTURE...WITH OBSERVED PRECIPITABLE WATER VALUES OF ONLY AROUND THREE QUARTERS OF AN INCH AT GSO AND MHX. FURTHERMORE...SURFACE DEWPOINTS REMAIN RELATIVELY MODEST EVEN AHEAD OF THE FRONT OVER THE WESTERN PIEDMONT AND FOOTHILLS...WHERE SURFACE DEWPOINTS AT 02Z WERE ONLY IN THE MID-UPPER 50S. RELATIVELY RICHER LOW LEVEL MOISTURE...CHARACTERIZED BY SURFACE DEWPOINTS IN THE LOWER TO MIDDLE 60S...WAS OBSERVED OVER THE REMAINDER OF CENTRAL NC. DESPITE THE LIMITED MOISTURE...THERE HAS ALREADY BEEN REDEVELOPMENT OF A RELATIVELY STRONG LINE OF STORMS FROM NEAR TDF TO BUY; AND THIS ACTIVITY...AS WELL AS NEW ISOLATED TO WIDELY SCATTERED DEVELOPMENT ALTOGETHER...WILL REMAIN POSSIBLE UNTIL THE AFOREMENTIONED FRONT AND UPPER FORCING CLEAR CENTRAL NC. BOTH LOW AND DEEP LAYER SHEAR...THE LATTER OF WHICH IS CHARACTERIZED STILL BY LONG AND STRAIGHT HODOGRAPHS FROM OBSERVED PROXIMITY RAOB DATA...ARE MORE THAN SUPPORTIVE OF ORGANIZED STORM MODES...INCLUDING SUPERCELLS AND/OR BOWS WITHIN MULTI-CELL LINE SEGMENTS. POST-FRONTAL LOW TEMPS...ACCOMPANIED BY MUCH LOWER RELATIVE HUMIDITY VALUES BY DAYBREAK...SHOULD RANGE FROM AROUND 50 DEGREES NW TO AROUND 60 SE.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 330 PM MONDAY... THE COLD FRONT WILL HAVE PUSHED JUST SE OF THE FORECAST AREA BY DAYBREAK TUE... WITH HIGH PRESSURE BUILDING IN FROM THE GULF STATES... THEN DRIFTING ACROSS GA/SRN SC. FORECAST SOUNDINGS SHOW A STABLE AND DRY COLUMN WITH JUST A FEW FLAT CU NEAR THE TOP OF THE MIXED LAYER IN THE AFTERNOON. A PASSING WEAK VORTICITY MAX COULD ALSO BRING A STREAM OF MID/HIGH CLOUDS IN THE EVENING. HIGHS BELOW NORMAL AT 68-74 WITH PARTLY TO MOSTLY SUNNY SKIES. MOSTLY CLEAR TUE NIGHT WITH THE HIGH SHIFTING OFF THE COAST. LOWS 44-50. -GIH && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 300 PM MONDAY... WEDNESDAY THROUGH THURSDAY NIGHT...DRY CONDITIONS WILL PERSIST ON WEDNESDAY AS HIGH PRESSURE ACROSS THE SOUTHEAST US GRADUALLY SLIPS OFFSHORE WEDNESDAY MORNING/EARLY AFTERNOON. ANOTHER COLD FRONT WILL APPROACH THE AREA LATE WEDNESDAY INTO THURSDAY. HOWEVER...LIMITED MOISTURE RETURN AHEAD OF THIS SYSTEM WILL KEEP PRECIP CHANCES MINIMAL. NEVERTHELESS...WILL KEEP A SLIGHT CHANCE POP IN THE FORECAST FOR WEDNESDAY NIGHT/EARLY THURSDAY...BUT MOST PLACES WILL LIKELY STAY DRY AND THOSE THAT SEE PRECIP WILL HAVE MEAGER AMOUNTS. HIGHS ON WEDNESDAY WILL RISE INTO THE MID/UPPER 70S...WHILE ON THURSDAY HIGHS WILL RANGE FROM THE UPPER 60S ACROSS THE NORTH (EARLIER FRONTAL PASSAGE) TO THE MID 70S FURTHER SOUTH. OVERNIGHT LOWS WILL GENERALLY BE IN THE MID/UPPER 40S TO LOWER 50S (COOLEST THURSDAY NIGHT BEHIND THE FRONT). FRIDAY THROUGH MONDAY...UNCERTAINTY REMAINS FAIRLY HIGH WITH RESPECT TO THE END OF THE WEEK AND ESPECIALLY INTO THE WEEKEND. THE OVERALL PATTERN INDICATES THE AFOREMENTIONED COLD FRONT WILL STALL JUST SOUTH OF THE REGION FOR THE END OF THE WEEK. THEN...AS A SOUTHERN STREAM SYSTEM APPROACHES...MULTIPLE WAVES OF LOW PRESSURE WILL RIDE ALONG THIS BOUNDARY...SPREADING PRECIP BACK INTO THE AREA. HOWEVER...AS CAN BE EXPECTED THIS FAR OUT...DETAILS HAVE YET TO BE WORKED OUT. REGARDLESS...WILL SHOW POPS EARLY IN THE WEEKEND WITH... AS OF NOW AT LEAST...DRIER CONDITIONS BY SUNDAY. MONDAY ALSO LOOKS TO BE DRY...BUT ANOTHER SYSTEM IS PROGGED TO BE ON OUR DOORSTEP BY LATE MONDAY/MONDAY NIGHT. TEMPS WILL GENERALLY BE NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE TIME FRAME. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 735 PM MONDAY... SCATTERED STORMS WILL CONTINUE TO AFFECT PORTIONS OF CENTRAL NC WITH BRIEF PERIODS OF SUB-VFR CONDITIONS. ONE BAND OF SCATTERED STORMS WILL AFFECT RDU THROUGH 03Z... AND WILL POTENTIALLY REACH RWI AFFECTING THAT SITE 02Z-05Z. AT THIS TIME... IT APPEARS THAT THE STORMS WILL HOLD LARGELY TO THE NORTHEAST OF FAY. A SECOND BAND OF STORMS OVER THE NRN FOOTHILLS AND NRN MOUNTAINS OF NC MAY SKIRT NEAR INT BUT IS ALSO EXPECTED TO STAY MAINLY NW OF THE TRIAD. BRIEF MVFR TO IFR CONDITIONS ARE POSSIBLE IN AND NEAR STORMS... AS WELL AS PEA TO QUARTER SIZE HAIL. OTHERWISE... VFR CONDITIONS WILL DOMINATE THROUGH TONIGHT. WINDS FROM THE SW AT 10-15 KTS GUSTING TO 20-25 KTS WILL PERSIST... VEERING AROUND TO WESTERLY WITH DIMINISHING GUSTS AFTER PASSAGE OF A COLD FRONT AFTER 04Z. A SHORT PERIOD OF MVFR CIGS ARE POSSIBLE WITH FRONTAL PASSAGE... BUT GENERALLY WE EXPECT VFR CONDITIONS LATE TONIGHT THROUGH THE END OF THE TAF VALID PERIOD WITH MOSTLY CLEAR SKIES. LOOKING BEYOND 00Z WED... VFR CONDITIONS SHOULD HOLD THROUGH WED AS HIGH PRESSURE BUILDS OVER THE REGION. A FEW HOURS OF SUB-VFR CIGS/VSBYS WITH A FEW SHOWERS ARE POSSIBLE WED EVENING/NIGHT INTO EARLY THU AS A DISTURBANCE MOVES QUICKLY ACROSS THE DEEP SOUTH AND SOUTHEAST STATES. VFR CONDITIONS AND COOLER WEATHER WILL FOLLOW FOR LATE THU INTO SAT. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...RAH SHORT TERM...HARTFIELD LONG TERM...KRD AVIATION...HARTFIELD

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