Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 191948 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 345 PM EDT SUN APR 19 2015 .SYNOPSIS...A WARM FRONT OVER SOUTH CAROLINA WILL LIFT NORTHEAST ACROSS NORTH CAROLINA THIS EVENING AS AN AREA OF LOW PRESSURE MOVES NORTHEAST INTO THE EASTERN GREAT LAKES ON MONDAY. A COLD FRONT WILL MOVE INTO THE MOUNTAINS FROM THE WEST MONDAY AFTERNOON AND THEN TRACK EAST TO THE CAROLINA COAST LATE MONDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION FOR TUESDAY AND WEDNESDAY. && .NEAR TERM /TONIGHT/... AS OF 345 PM SUNDAY... COMPLICATED FORECAST FOR THIS EVENING AND OVERNIGHT WITH A THREAT OF HEAVY RAIN AND FLOODING ISSUES AND A SMALL THREAT OF SEVERE WEATHER ACROSS THE SOUTH. WIDESPREAD AREA OF MAINLY LIGHT TO MODERATE RAIN SHIFTING ACROSS CENTRAL NC THIS AFTERNOON IS LARGELY ASSOCIATED WITH A NORTHWARD ADVANCING WARM FRONT IN A VEERING WIND PROFILE. BOUNDARY LAYER DEW POINTS CONTINUE TO RISE WITH DEW POINTS IN THE UPPER 60S ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS. ANOTHER REGION OF CONVECTION EXTENDS FROM SOUTHWESTERN NC SOUTHWARD TO COASTAL GA. THIS AREA OF CONVECTION IS BEING SUPPORTED BY A MID LEVEL SHORT WAVE APPROACHING A REGION OF MODERATE INSTABILITY. THIS AREA HAS SHOWN AN INCREASING TREND IN TERMS OF COVERAGE AND INTENSITY AS IT MOVES EAST AND NORTHEAST. CONVECTION ALLOWING MODELS BRING THIS AREA OF CONVECTION NORTHEAST INTO CENTRAL NC THIS EVENING THROUGH A LITTLE AFTER MIDNIGHT. MOST OF THE PRECIPITATION SHOULD HAVE CLEARED CENTRAL NC BY AROUND 200 AM. A LOW-END SEVERE WEATHER THREAT...MAINLY IN THE FORM OF A DAMAGING WIND GUST OR BRIEF TORNADO IS POSSIBLE BETWEEN 22-06Z...MAINLY ACROSS THE SOUTHERN PORTION OF THE CWA. A TORNADO WATCH IS CURRENTLY IN EFFECT THROUGH 800 PM JUST TO THE SOUTHWEST OF THE RAH CWA. IN ADDITION TO THE LIMITED BUT NON-ZERO TORNADO THREAT...A TRANSITORY AREA OF HEAVY RAIN IS EXPECTED TO MOVE NORTHEAST ACROSS CENTRAL NC THIS EVENING INTO THE EARLY OVERNIGHT HOURS WITH A ONE OR TWO HOUR PERIOD OF HEAVY RAIN. WHILE WIDESPREAD FLASH FLOODING IS NOT EXPECTED...URBAN AREAS AND TYPICALLY SUSCEPTIBLE AREAS IN THE WESTERN PIEDMONT AND YADKIN VALLEY AREAS ARE MOST AT RISK. TEMPERATURES WILL SHOW A LIMITED DIURNAL TREND TONIGHT WITH THE CLOUD COVER...PRECIPITATION AND SOUTHEAST BREEZE AT 10-15 MPH THAT BECOMES SOUTHWESTERLY OVERNIGHT. LOWS WILL RANGE IN THE LOWER TO MID 60S. -BLAES && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 400 AM SUNDAY... EXPECT A CLEARING TREND MONDAY MORNING THROUGH EARLY AFTERNOON AS LINGERING LOW STRATUS LIFTS AND BECOMES CU/TCU WITH BASES OF 3-4 KFT BY EARLY AFTERNOON. A MODIFIED ELEVATED MIXED LAYER CHARACTERIZED BY H7-H5 LAPSE RATES ON THE ORDER OF 7 C/KM IS PROGGED TO ADVECT INTO THE REGION LATE TONIGHT...MAINTAINED BY WSW/SW FLOW ALOFT DURING THE DAY MONDAY. LOW-LEVEL MOISTURE (SFC DWPT UPPER 50S TO LOWER 60S) WILL PERSIST THROUGHOUT THE DAY...WITHIN AN INCREASINGLY WELL-MIXED WARM SECTOR DOWNSTREAM OF A COLD FRONT APPROACHING THE MOUNTAINS FROM THE WEST DURING THE LATE AFT/EVE. GIVEN STRONG DIURNAL HEATING AND STEEP MID-LEVEL LAPSE RATES ATOP SEASONABLY IMPRESSIVE LOW-LEVEL MOISTURE...MODERATE DESTABILIZATION IS EXPECTED WITH MLCAPE VALUES SOLIDLY IN THE 1500-2500 J/KG RANGE. THOUGH LITTLE IN THE WAY OF A CAP IS PRESENT MON AFTERNOON PER THE LATEST GUIDANCE/FORECAST SOUNDINGS...CONVECTION IS UNLIKELY TO DEVELOP BEYOND THE `TURKEY TOWER` STAGE THROUGH MID AFTERNOON (~21Z) GIVEN SUCH A DRY AIRMASS ALOFT...AN INSUFFICIENT FOCUS...AND AN OVERAL LACK OF DEEPER ASCENT. BY LATE AFTERNOON (~21Z)...MODERATE/UNTAPPED INSTABILITY AND AN ABSENCE OF CONVECTIVE INHIBITION ARE EXPECTED TO ALLOW RAPID CONVECTIVE DEVELOPMENT ALONG THE COLD FRONT /PRE-FRONTAL TROUGH/ PROGRESSING INTO THE FOOTHILLS...GROWING UPSCALE INTO A SQUALL LINE BETWEEN 21-00Z AS ADDITIONAL CONVECTION DEVELOPS ALONG OUTFLOW IN AN ENVIRONMENT CHARACTERIZED BY WESTERLY LOW-LEVEL SHEAR AND MODERATE/ HIGH DCAPE. WILL INDICATE A 50% CHANCE OF SHOWERS/STORMS MOVING WEST- EAST ACROSS CENTRAL NC BETWEEN 21-03Z. SEVERE THREAT: WITH THE ABOVE ENVIRONMENT IN MIND...ANY STORMS THAT DEVELOP COULD BECOME SEVERE...WITH A PRIMARY THREAT OF DAMAGING WINDS. QUARTER TO GOLFBALL SIZE HAIL WOULD BE POSSIBLE IN ASSOC/W ROTATING UPDRAFTS...PARTICULARLY DISCRETE UPDRAFTS (I.E. INITIALLY IN WESTERN PIEDMONT). AN ENHANCED THREAT OF DAMAGING WINDS WILL BE PRESENT ALONG/EAST OF HWY 1 IF UPSCALE GROWTH INTO A MATURE MCS OCCURS WITHIN THE ENVIRONMENT PROGGED BY GUIDANCE. -VINCENT && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 330 PM SUNDAY... TUESDAY THROUGH WEDNESDAY...COLD FRONT WILL HAVE MOVED OFFSHORE BY TUESDAY MORNING WITH DRY CONDITIONS RETURNING TO CENTRAL NC. HIGH PRESSURE WILL SHIFT ACROSS THE SOUTHEAST US TUESDAY INTO TUESDAY NIGHT...BEFORE MOVING OFFSHORE BY WEDNESDAY MORNING/EARLY AFTERNOON. DURING THIS TIME FRAME...DRY CONDITIONS WILL PERSIST WITH TEMPS RUNNING NEAR TO SLIGHTLY BELOW NORMAL. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...ANOTHER COLD FRONT WILL APPROACH THE AREA LATE WEDNESDAY INTO THURSDAY. HOWEVER...LIMITED MOISTURE RETURN AHEAD OF THIS SYSTEM WILL KEEP PRECIP CHANCES ON THE LOW END. NEVERTHELESS...WILL KEEP A SLIGHT CHANCE POP IN THE FORECAST FOR EARLY THURSDAY...BUT MAINLY CONFINED TO THE SOUTHEAST HALF OF THE FORECAST AREA. HIGHS ON THURSDAY WILL RANGE FROM THE UPPER 60S ACROSS THE NORTH (EARLIER FRONTAL PASSAGE) TO THE MID/UPPER 70S FURTHER SOUTH. FRIDAY THROUGH SUNDAY...THERE IS FAIRLY HIGH UNCERTAINTY WITH REGARD TO THE END OF THE WEEK AND ESPECIALLY INTO NEXT 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 FOR EARLY IN THE WEEKEND WITH (AS OF NOW AT LEAST) DRIER CONDITIONS BY SUNDAY. TEMPS WILL GENERALLY BE NEAR TO SLIGHTLY BELOW NORMAL. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/... AS OF 245 PM SUNDAY... 24 HOUR PERIOD...MULTIPLE ROUNDS OF SHOWERS AND POSSIBLY EMBEDDED THUNDERSTORMS ACROSS THE SOUTH WILL MOVE ACROSS CENTRAL NC THIS AFTERNOON AND EVENING RESULTING IN WIDESPREAD ADVERSE AVIATION CONDITIONS WITH CEILINGS DROPPING TO IFR AND LIFR LEVELS AT TIMES AND MVFR VSBYS BECOMING IFR IN HEAVY RAIN. A LULL IN PRECIPITATION AND A BRIEF RELAXING OF CIGS/VSBYS WILL MOVE FROM SOUTHWEST TO NORTHEAST LATE THIS AFTERNOON AND EVENING BEFORE THE SECOND ROUND OF LIKELY. HEAVIER PRECIPITATION IMPACTS THE AREA ROUGHLY BETWEEN 22Z AND 05Z. GENERALLY LIGHT RAIN SHOWERS ARE EXPECTED AFTER 06Z...MOST COMMONLY ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN WITH DRY WEATHER EXPECTED FROM THE PRE DAWN HOURS ON MONDAY THROUGH EARLY MONDAY AFTERNOON. LOW CLOUDS WILL PERSIST OVERNIGHT WITH CIGS GENERALLY BELOW 1KFT AND FREQUENTLY LESS THAN 500 FT. CIGS WILL IMPROVE ON MONDAY MORNING WITH VFR CONDITIONS EXPECTED BY LATE MORNING WITH A SCT-BKN CUMULUS LAYER DEVELOPING AND RANGING BETWEEN 3-4KFT. LOOKING FURTHER AHEAD...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP MONDAY AFTERNOON ACROSS THE FOOTHILLS AND SPREAD EAST INTO THE WESTERN PIEDMONT VERY LATE IN THE AFTERNOON AND THEN MOVE ACROSS CENTRAL NC DURING THE EVENING HOURS. ADVERSE AVIATION CONDITIONS INCLUDING GUSTY WINDS AHEAD OF THE FRONT AND ACCOMPANYING CONVECTION WITH AREAS OF MVFR/IFR CIGS AND VBSYS ARE EXPECTED. A RETURN TO VFR CONDITIONS ARE EXPECTED MONDAY NIGHT THROUGH THURSDAY AS HIGH PRESSURE BUILDS IN. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...VINCENT LONG TERM...KRD AVIATION...BLAES

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