Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 130050 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 845 PM EDT FRI SEP 12 2014 .SYNOPSIS...A FRONTAL ZONE MEANDERING OVER THE REGION WILL BRING UNSETTLED WEATHER TO CENTRAL NC THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 845 PM FRIDAY.. INCREASED HEAVY RAIN AND POSSIBLY FLASH FLOOD THREAT IN THE SOUTHERN PIEDMONT... SANDHILLS... AND SE COASTAL PLAIN... A FLASH FLOOD WATCH IS BEING CONSIDERED FROM STANLY AND ANSON COUNTIES EAST TO CUMBERLAND COUNTY OVERNIGHT INTO SATURDAY. THE MAIN FRONT EXTENDED ACROSS SOUTHERN SECTIONS OF NC AT MID- EVENING. THE FRONT EXTENDED ACROSS SOUTHERN STANLY COUNTY EAST ACROSS NORTHERN CUMBERLAND AND SAMPSON COUNTIES. IT IS ALONG THIS BOUNDARY THAT THE POTENTIAL FOR FLASH FLOODING WILL BE THE MAIN WEATHER HAZARD. ANTECEDENT CONDITIONS WERE ALREADY VERY WET FROM ALBEMARLE TO RALEIGH TO WARRENTON AND POINTS SOUTHWARD INTO NE SOUTH CAROLINA... ROUGHLY NEAR THE CURRENT FRONTAL POSITION. THIS WSS BEST ILLUSTRATED BY THE LATEST SOIL MOISTURE PROFILE INFORMATION. IN ADDITION... LOCALLY VERY HEAVY RAINFALL FELL THIS AFTERNOON AND EARLY EVENING ALONG AND SOUTH OF ALBEMARLE TO TROY TO FAYETTEVILLE. SOME LOCAL 2-3 INCH TOTALS WERE REPORTED IN AN HOUR PRODUCING MINOR FLOODING IN ANSON... RICHMOND... CUMBERLAND AND SAMPSON COUNTIES. ALSO... RAINFALL REPORTS IN THE PAST 3... 7... 14... AND 30 DAYS INDICATE A GOOD PORTION OF THIS SAME REGION HAS RECEIVED 150 TO 250 PERCENT OF NORMAL RAINFALL. FOR THE OVERNIGHT... AS THE CONVECTION WANES ALONG THE COAST WHERE SEA BREEZE INTERACTION SET OFF THE CONVECTION EARLIER... THE FOCUS WILL RETURN BACK TO THE LOW LEVEL BOUNDARY OVER SOUTHERN NC FOR ISOLATED EXCESSIVE RAINFALL... AS THE LOW LEVEL WINDS BACK SLOWLY TO THE SE-S (IN SOME CASES JUST ABOVE THE FRONTAL ZONE). ALTHOUGH THE SURFACE TO H85 WINDS ARE RELATIVELY WEAK... THE UPPER DIVERGENCE BECOMES FAVORABLE FOR INCREASING LARGE SCALE LIFT OVERNIGHT. THE PRECIPITABLE WATER VALUES ARE ALSO POOLED ALONG THE FRONT WITH PRECIPITABLE WATER VALUES OF 2 INCHES OR MORE. WHEN COMBINED WITH A LIGHT STEERING FLOW... THE SHOWERS AND THUNDERSTORMS THAT FORM WILL CONTINUE TO BE VERY SLOW MOVERS ENHANCING THE EXCESSIVE RAINFALL THREAT. AS PREVIOUSLY MENTIONED... THE FOCUS SHOULD BEGIN IN THE WESTERN AREAS WHERE THE APPROACH OF THE SHORT WAVE AND ASSOCIATED STRONG MID/UPPER LEVEL VORTICITY MAXIMUM WILL OCCUR FIRST. SHOWERS AND SCATTERED THUNDERSTORMS HAVE ALREADY BEGUN DEVELOPING OVER THE MOUNTAINS IN RESPONSE TO THE APPROACH OF THE UPPER LEVEL FEATURE ALONG WITH THE CONVERGENCE AND LIFT WITH THE BOUNDARY OVER THE MOUNTAINS AND THE UPSLOPE EASTERLY FLOW. WIDESPREAD SHOWERS ARE EXPECTED TO OVERSPREAD THE WESTERN AND SOUTHERN SECTIONS AGAIN LATER TONIGHT. DUE TO THE CONDITIONS MENTIONED ABOVE... LOCALLY HEAVY RAIN AND POSSIBLY FLASH FLOODING WILL BE POSSIBLE AS 2-3 INCHES OF RAIN IN 3 HOURS AND/OR 3+ INCHES MAY OCCUR LATER TONIGHT INTO SATURDAY. POPS TO THE NORTH AND EAST OF GSO AND RDU SHOULD BE LOWER GIVEN THE LOW LEVEL STABILITY AND SLIGHTLY (EMPHASIS ON SLIGHTLY) DRIER LOW LEVEL AIR COURTESY OF THE SURFACE HIGH BUILDING INTO THIS REGION FROM THE NE.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 305 PM FRIDAY... EXPECT SOME PRECIP TO BE ONGOING OVER THE WESTERN CWA SATURDAY MORNING IN RESPONSE TO A WEAK WAVE MOVING ALONG THE STALLED FRONTAL ZONE DRAPED ACROSS NC. THE PORTION OF THE FRONT STALLED TO OUR SOUTH SHOULD LIFT BACK NORTH INTO OUR AREA...WITH BETTER MODEL AGREEMENT TODAY ON THE FRONT MOVING BACK AT LEAST HALFWAY THROUGH THE AREA...LYING SOUTHWEST TO NORTHEAST ACROSS THE AREA BY MIDDAY SATURDAY. OVERNIGHT RAIN AND STABILIZATION IN THE NORTHWEST PIEDMONT MAY PREVENT IT FROM MOVING FURTHER WEST. MEANWHILE... THE COLD FRONT WEST OF THE MOUNTAINS WILL MOVING INTO THE AREA FROM THE WEST DURING THE AFTERNOON...WITH THE ENTIRE SYSTEM EXPECTED TO SINK BACK SOUTH THROUGH THE AREA SATURDAY NIGHT AS STRONGER HIGH PRESSURE NOSES IN FROM THE NORTH. SCATTERED TO POTENTIALLY NUMEROUS SHOWERS AND STORMS SHOULD DEVELOP BY SATURDAY AFTERNOON ALONG FRONT(S)...WITH MODELS SHOWING 1000-1500 J/KG AND PW OVER 2 INCHES AGAIN IN THE WARM SECTOR. IF CONVECTION IS FAIRLY WIDESPREAD...COULD SEE ANOTHER HALF TO ONE INCH OF RAINFALL WITH LOCALLY HIGHER AMOUNTS OF UP TO A COUPLE INCHES. HIGHS SHOULD RANGE FROM THE LOW/MID 70S WEST TO LOW/MID 80S EAST...THOUGH GUIDANCE SUGGESTS SOME BREAKS IN CLOUD COVER BEHIND THE COLD FRONT COULD BRIEFLY ALLOW TEMPS IN THE WEST TO REACH THE UPPER 70S. THE FRONT AND ASSOCIATED PRECIP WILL SHIFT SOUTH SATURDAY NIGHT...WITH DRIER AIR AGAIN MOVING IN FROM THE NORTH AND HIGH PRESSURE RIDGING SOUTH BEHIND THE FRONT. LOWS IN THE LOWER 60S NORTHWEST TO UPPER 60S SOUTHEAST. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS OF 245 PM FRIDAY... VERY LOW CONFIDENCE FORECAST FOR THE LONG TERM AS DISCREPANCIES REMAIN IN THE MODELS ON WHERE THE FRONT WILL STALL OUT OVER THE WEEKEND MAKING BOTH PRECIPITATION AND TEMPERATURE FORECASTS VERY DIFFICULT AT THIS TIME. FOR SUNDAY THE FRONT IS PROGGED TO MOVE THROUGH NORTH CAROLINA...STALLING SOMEWHERE SOUTH OF THE AREA AS A HIGH PRESSURE SYSTEM OVER THE NORTHEAST SETS UP A POTENTIAL WEDGE BOUNDARY SOMEWHERE ACROSS THE CWA. THE TRANSIENT NATURE AND RELATIVE WEAKNESS OF THE HIGH LEAVE DOUBTS ABOUT HOW STRONG THE WEDGE MAY BE. WHILE MOST CONVECTIVE PRECIP SHOULD STAY SOUTH OF THE AREA...THE GFS LEAVES THE DOOR OPEN FOR SOME OVERRUNNING PRECIP SUNDAY AFTERNOON. REGARDLESS OF PRECIPIATION...ABUNDANT CLOUD COVER SHOULD KEEP TEMPERATURES DOWN ON SUNDAY WITH HIGHS GENERALLY IN THE LOWER 70S WITH LOWS IN THE LOWER 60S. ON MONDAY THE FRONT IS EXPECTED TO RETROGRADE BACK NORTH OF THE AREA AND EVENTUALLY COMBINE WITH A SECOND FRONT MOVING IN FROM THE NW... WHICH WILL INCREASE CONVECTIVE PRECIPITATION CHANCES AND LIFT TEMPERATURES BACK INTO THE UPPER 70S. AN INCREASE IN MOISTURE WILL HELP CLOUDY SKIES TO PREVAIL WITH RAIN CHANCES THROUGH THE DAY. LOWS WILL MODERATE INTO THE MID TO UPPER 60S WITH A CONTINUED CHANCE FOR RAIN OR A POSSIBLE THUNDERSHOWER OVERNIGHT MONDAY NIGHT. THIS PATTERN WILL REMAIN INTACT THROUGH TUESDAY AFTERNOON...PRODUCING SIMILAR TEMPERATURES WITH HIGHS IN THE UPPER 70S. SURFACE HIGH PRESSURE OVER THE OHIO VALLEY WILL BEGIN TO PUSH EASTWARD TUESDAY EVENING...USHERING THE FRONT BACK SOUTH OF THE AREA BY TUESDAY NIGHT. THE RATHER AGGRESSIVE MOVEMENT OF THE HIGH SHOULD DRY THINGS OUT TUESDAY NIGHT AND HELP TO DROP THE LOWS CONSIDERABLY...WITH TEMPERATURES IN THE UPPER 50S NW TO LOW 60S SE. THE LATTER HALF OF THE WEEK LOOKS MUCH DRIER AS HIGH PRESSURE BEGINS TO DOMINATE THE PATTERN. NORTHEASTERLY FLOW WILL STILL BRING A FAIR AMOUNT OF CLOUD COVER. THIS COUPLED WITH SOME FAIRLY DECENT COLD AIR ADVECTION SHOULD KEEP HIGH TEMPERATURES DOWN IN THE LOW TO MID 70S. THERE ARE SOME DISCREPANCIES IN REGARDS TO SHORTWAVE ENERGY MOVING OUT OF THE GULF OF MEXICO UP ALONG THE FRONT AND SPREADING PRECIP BACK OVER THE AREA...BUT CONFIDENCE IN THIS IS LOW AT THIS TIME AND ONLY SLIGHT CHANCE POPS WILL BE CARRIED FOR WEDNESDAY AND THURSDAY. LOWS IN THE UPPER 50S TO LOWER 60S. && .AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 845 PM FRIDAY... OVERNIGHT...A WAVE IS FORECAST TO MOVE ALONG THE STATIONARY FRONT OVER SOUTHERN NC. THIS WILL CAUSE SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP ACROSS WESTERN AND SOUTHERN NC OVERNIGHT. THEY WILL LIKELY IMPACT KGSO/KINT/FAY AS CEILINGS FALL TO IFR AND/LIFR OVER MUCH OF CENTRAL NC. MEANWHILE...THE WAVE AND FRONT WILL AFFECT MUCH OF SOUTHERN AND EASTERN NC SATURDAY WITH SHOWERS AND STORMS ON SATURDAY...MAINLY FROM KRDU TO THE SOUTH AND EAST. CEILINGS MAY SEE SOME IMPROVEMENT DURING THE DAY BEFORE FALLING BACK TO IFR OR LOWER ON SATURDAY NIGHT. OUTLOOK...THE STALLED FRONT SHOULD FINALLY SHIFT SE SUNDAY NIGHT AND MONDAY... WITH ADVERSE AVIATION CONDITIONS BREAKING SOMEWHAT OVER CENTRAL NC.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...PWB SHORT TERM...BLS LONG TERM...ELLIS AVIATION...BSD

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