Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 052036 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 436 PM EDT THU MAY 5 2016 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SWING ACROSS NORTH CAROLINA TONIGHT AND MOVE TO NEAR DELAWARE BY MIDDAY FRIDAY. THE UPPER LOW WILL WOBBLE ACROSS THE MID ATLANTIC ON SATURDAY BEFORE MOVING OFFSHORE SATURDAY NIGHT. A COLD FRONT WILL DROP SOUTH INTO THE MID ATLANTIC ON SUNDAY AND THEN LINGER ACROSS THE CAROLINAS AND VIRGINIA ON MONDAY AND TUESDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 405 PM THURSDAY... AN ANOMALOUSLY STRONG 546DM CLOSED UPPER LEVEL LOW PRESSURE SYSTEM WAS LOCATED ACROSS SOUTHWESTERN NC AT 18Z. THE H5 LOW WAS NOTED TO BE BETWEEN 4 AND 5 STANDARD DEVIATIONS FROM NORMAL WITH A ROBUST 60-70KT JET EXTENDING FROM THE SAVANNAH RIVER VALLEY NORTHEAST AND OFF THE COAST. AN ARC OF DEEP MOISTURE WAS NOTED ACROSS TO THE NORTHEAST AND NORTHWEST OF THE UPPER LOW IN NORTHEAST NC AND SOUTHERN VA. A REGION OF WEAK INSTABILITY NOTED IN THE SPC ANALYSIS LATE THIS MORNING ACROSS THE EASTERN PIEDMONT AND SANDHILLS. THIS INSTABILITY HAS BEEN DAMPENED BY COOLING FROM THE RAIN TODAY AND A TRANSPORT OF SLIGHTLY DRIER DEW POINTS. ONLY VERY WEAK IN STABILITY WAS NOTED AT 18Z...RANGING BELOW 250 J/KG ACROSS THE SOUTHERN PIEDMONT TO THE SANDHILLS AND SOUTHERN COASTAL PLAIN...LARGELY IN THE REGION OUTSIDE OF THE STEADY RAIN. LATEST SPC ANALYSIS OF DEEP LAYER SHEAR SHOWS THE STRONGEST SHEAR IS SHIFTING EAST AND AWAY FROM CENTRAL NC WITH SHEAR VALUES NOW ONLY RANGING BETWEEN 30 TO 40 KTS ACROSS THE COASTAL PLAIN. NWP GUIDANCE INCLUDING HIGH RES CONVECTION ALLOWING MODELS ARE CONSISTENT IN BRINGING THE UPPER LOW EAST ACROSS THE NC/SC BORDER TONIGHT TO FAR NE NC BY DAYBREAK. WHILE THE AXIS OF HEAVIEST RAIN IS SHIFTING NORTHEAST INTO THE NORTHERN COASTAL PLAIN THIS AFTERNOON...ANOTHER SURGE OF PRECIPITATION WILL DROP SOUTH FROM VIRGINIA INTO THE WESTERN PIEDMONT THIS AFTERNOON AND EVENING BEFORE ROTATING EAST ACROSS MUCH OF CENTRAL NC OVERNIGHT. THE GREATEST PRECIPITATION COVERAGE WILL BE ACROSS THE NORTHERN HALF OF THE AREA TONIGHT WITH RAINFALL AMOUNTS RANGING BETWEEN 0.5 AND 1.0 INCHES IN MOST LOCATIONS WITH A FEW HIGHER AMOUNTS APPROACHING 1.5 INCHES. THE RAIN MAY BE HEAVY AT TIMES AND COULD RESULT IN SOME LOCALIZED URBAN AND SMALL STREAM FLOODING. THE PRECIPITATION AMOUNTS AND DURATION SHOULD BE LOW ENOUGH TO PRECLUDE THE NEED FOR A FLOOD WATCH WITH 3 HOUR FLASH FLOOD GUIDANCE RANGING BETWEEN 2 AND 3 INCHES. WIDESPREAD CLOUDINESS AND A COOL LOW LEVEL NORTHWEST FLOW WILL RESULT IN A CHILLY AND DAMP NIGHT. LOWS WILL RANGE IN THE UPPER 40S ACROSS THE WESTERN PIEDMONT AND TRIAD AREA AND IN THE LOWER 50S ELSEWHERE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 435 PM THURSDAY... THE UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE FROM NORTHEASTERN NC AT DAYBREAK FRIDAY TO THE WASHINGTON DC AREA ON FRIDAY AFTERNOON AND FRIDAY NIGHT. THE UPPER LOW WILL WOBBLE A BIT LATE IN THE PERIOD BUT LIKELY LINGER IN THE DC-PHILADELPHIA REGION BY SATURDAY MORNING. WHILE THE FORCING FOR ASCENT GRADUALLY WEAKENS ACROSS CENTRAL NC DURING THE PERIOD...THERE SHOULD BE ENOUGH MOISTURE PRESENT WITH ANOTHER COUPLE SHORT WAVE TROUGHS ROTATING AROUND THE BACK SIDE OF THE UPPER LOW TO WARRANT POPS ON FRIDAY. EXPECT THE COVERAGE AND INTENSITY TO BE MORE LIMITED ON FRIDAY AS COMPARED TO TODAY WITH THE BEST CHANCE DURING THE AFTERNOON WHEN SOME LIMITED HEATING SHOULD BE SUFFICIENT TO SUPPORT SCATTERED SHOWERS. HAVE INCLUDED THE MENTION OF A SLIGHT CHANCE OF THUNDERSTORMS IN THE EAST AND SOUTHEAST WHERE DEW POINTS IN THE LOWER 50S COMBINED WITH SOME DECENT LOW/MID LEVEL LAPSE RATES COULD BE SUFFICIENT TO GENERATE A FEW THUNDERSTORMS. BULK SHEAR VALUES WILL BE WEAK BUT WITH H5 RANGING BETWEEN -20 AND -23...CANT RULE OUT A LITTLE SMALL HAIL. THREAT OF PRECIPITATION DECREASES IN THE EVENING AND WILL TREND POPS DOWN TO SLIGHT CHANCE NORTH AND EAST IN THE EVENING WITH NO POPS OVERNIGHT AND DECREASING CLOUDS. HIGHS ON FRIDAY WILL RANGE IN THE LOWER 60S NORTHEAST TO UPPER 60S SOUTH AND LOWS FRIDAY NIGHT WILL RANGE AROUND 50. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 300 PM THURSDAY... SATURDAY AND SUNDAY...THE UPPER LOW THAT WILL HAVE BEEN PARKED OVER THE REGION FOR SEVERAL DAYS WILL FINALLY BE START TO SHIFT EAST OF THE AREA ON SATURDAY...BUT WILL STAY RELATIVELY CLOSE TO NORTHEAST NC UNTIL SUNDAY WHEN ANOTHER TROUGH MOVING ACROSS EASTERN CANADA/NEW ENGLAND WILL FINALLY PUSH IT OFFSHORE. THIS NEXT TROUGH WILL PUSH A COLD FRONT TOWARDS THE REGION ON LATE SATURDAY NIGHT INTO SUNDAY... WHEN IT WILL LIKELY STALL NEAR/OVER THE AREA. WITH ALL OF THIS IN MIND...MOSTLY COOL AND DRY CONDITIONS ARE EXPECTED FOR SATURDAY... ALTHOUGH A FEW SHOWERS MAY POP DURING DAYTIME HEATING ON SATURDAY ACROSS THE NORTHEAST DEPENDING ON THE ULTIMATE PROXIMITY OF THE UPPER LOW. THEN BY SATURDAY NIGHT AND SUNDAY...A FEW SHOWERS MAY DEVELOP ON THE FRONTAL ZONE...MAINLY ACROSS THE NORTHERN COUNTIES. OTHERWISE...TEMPS ARE EXPECTED TO BE IN THE MID TO UPPER 70S ON SATURDAY...AND DESPITE THE "COLD FRONT" ON SUNDAY...STRONGER DOWNSLOPE FLOW SHOULD ALLOW TEMPS TO WARM INTO THE UPPER 70S TO LOWER 80S (WARMEST ACROSS THE SOUTH). MONDAY THROUGH THURSDAY...WEAK RIDGING WILL BUILD OVER THE AREA EARLY NEXT WEEK. THIS...ALONG WITH DEVELOPING RETURN FLOW...WILL RESULT IN A SOME MODERATION...WITH HIGH TEMPS RISING SOLIDLY INTO THE MID 80S. MODELS ARE THEN SHOWING A LARGE BUT RATHER DISORGANIZED SYSTEM MOVING EAST TOWARDS THE REGION THROUGH MID WEEK. GIVEN THE LACK OF ORGANIZATION...MODELS ARE HAVING A TOUGH TIME RESOLVING THE DETAILS. THEREFORE...WILL JUST SHOW AN INCREASE IN CLOUDINESS AND PRECIP CHANCES DURING THIS TIME FRAME. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... WIDESPREAD ADVERSE AVIATION CONDITIONS ARE EXPECTED THIS AFTERNOON THROUGH EARLY FRIDAY MORNING. MVFR TO IFR CONDITIONS WILL DOMINATE ACROSS MUCH OF CENTRAL NC THROUGH TONIGHT. A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE CAROLINAS THIS AFTERNOON AND TONIGHT AND THEN LIFT NORTH TO NEAR DELAWARE BY FRIDAY AFTERNOON. SEVERAL AREAS OR CLUSTERS OF SHOWERS AND EVEN FEW THUNDERSTORMS THIS AFTERNOON WILL ROTATE AROUND THE UPPER LOW THROUGH THE PERIOD. AN AREA OF WIDESPREAD RAIN ACROSS THE EASTERN PIEDMONT AND THE COASTAL PLAIN EARLY THIS AFTERNOON WILL PIVOT NORTH TOWARD EARLY EVENING WITH A LULL OVER MUCH OF THE AREA BEFORE ANOTHER AREA OF WIDESPREAD SHOWERS DROP SOUTH FROM SOUTHERN VA TONIGHT AND SPREADS EAST ACROSS THE AREA. SCATTERED THUNDERSTORMS ARE EXPECTED THROUGH EARLY THIS EVENING...MAINLY ACROSS THE EASTERN PIEDMONT...COASTAL PLAIN AND SANDHILLS INCLUDING KRDU/KRWI/KFAY. EVEN WITH THE LULL OR BREAKS IN THE RAIN TONIGHT...WIDESPREAD IFR CIGS AND MVFR/IFR VSBYS ARE EXPECTED. CIGS AND VSBYS WILL BEGIN TO IMPROVE DURING THE LATE MORNING FRIDAY WITH VFR CONDITIONS BECOMING MORE PROMINENT DURING THE AFTERNOON. LOOKING FURTHER AHEAD BEYOND 18Z FRIDAY... AVIATION CONDITIONS WILL CONTINUE TO IMPROVE ON FRIDAY AND FRIDAY NIGHT WITH JUST A SMALL CHANCE OF A SHOWER. OTHERWISE...MAINLY VFR CIGS AND VSBYS ARE EXPECTED. DESPITE PERIODS OF CLOUDINESS AND A SMALL THREAT OF A SHOWER...VFR CONDITIONS SHOULD PREVAIL OVER THE WEEKEND INTO MONDAY BEFORE THE NEXT STORM SYSTEM APPROACHES ON TUESDAY. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...BLAES LONG TERM...KRD AVIATION...BLAES

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