Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 230231 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1031 PM EDT WED APR 22 2015 .SYNOPSIS...A COLD FRONT WILL PUSH SOUTH THROUGH THE REGION LATE TONIGHT. HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT FOR THE END OF THE WORK WEEK. UNSETTLED WEATHER IS EXPECTED FOR THE WEEKEND. && .NEAR TERM /TONIGHT THROUGH THURSDAY NIGHT/... AS OF 1030 PM WEDNESDAY... THROUGH TONIGHT: A DRY COLD FRONT IS SINKING SOUTHWARD THROUGH SOUTHERN VA THIS EVENING AND SHOULD SLOWLY MOVE THROUGH CENTRAL NC OVERNIGHT. GIVEN THE WEST-SOUTHWEST TO WESTERLY LOW LEVEL FLOW AND DEEP DRY SUB-CLOUD LAYER NOTED ON THE KGSO 00Z SOUNDING... THE LOW LEVEL AIR MASS REMAINS QUITE DRY. THIS ALONG WITH A LACK OF ANY SIGNIFICANT DISTURBANCES ALOFT EXPECTED TO CROSS THE AREA... THINK DRY CONDITIONS WILL GENERALLY PREVAIL ALONG AND IN ADVANCE OF THE FRONT. THE ONE POSSIBLE EXCEPTION THOUGH MAY BE ACROSS THE SOUTHERN HALF OF THE AREA TONIGHT... AS A WEAK DISTURBANCE ALOFT IS HELPING TO PRODUCE SOME SHOWERS ACROSS THE SOUTHERN NC MOUNTAINS/NORTHERN GA/UPSTATE SC.... WITH SOME OF THIS ACTIVITY POSSIBLY CLIPPING SOUTHERN PORTIONS OF OUR AREA. AT BEST THINK ANY ACTIVITY FROM THIS DISTURBANCE SHOULD JUST PRODUCE TRACE AMOUNTS ACROSS FAR SOUTHERN PORTIONS OF CENTRAL NC... GENERALLY SPRINKLES IF ANYTHING. LOW TEMPS TONIGHT WILL DEPEND ON THE AMOUNT OF CAA. PLAN TO STAY CLOSE TO THE PREVIOUS FORECAST... WHICH IS NEAR STATISTICAL GUIDANCE VALUES. THIS YIELDS LOWS RANGING FROM THE MID 40S NORTH TO THE LOWER TO MID 50S SOUTH. -BSD FOR THU/THU NIGHT: EXPECT PLENTY OF SUNSHINE TOMORROW AS WEAK HIGH PRESSURE BUILDS IN FROM THE NW BEHIND THE FRONT. LOW LEVEL FLOW WILL BACK SLIGHTLY TO BE FROM THE WNW... AND WITH A DECENT HEIGHT GRADIENT JUST ALOFT AT 925 MB AND GOOD MIXING WITH HEATING... SUSTAINED WIND SPEEDS FROM MID MORNING ONWARD ARE LIKELY TO REBOUND TO 10-20 KTS... ALBEIT WITH MUCH LOWER GUSTS (IF ANY) THAN WE`VE SEEN TODAY. LOW LEVEL THICKNESSES ARE EXPECTED TO BE 30-40 M BELOW NORMAL THU MORNING... BUT WITH STRONG HEATING AND A NEARLY DRY ADIABATIC LOW LEVEL THERMAL PROFILE... EXPECT HIGHS IN THE MID 60S TO LOWER 70S... STILL SEVERAL DEGREES BELOW NORMAL. A WEAK REINFORCING TROUGH WILL DROP SE THROUGH NC LATE THU... WITH HIGH PRESSURE CONTINUING TO BUILD IN FROM THE NW... ITS CENTER EXPECTED TO BE JUST NW OF THE AREA BY SUNRISE FRI MORNING. WINDS WILL DIMINISH THURSDAY NIGHT WITH DECOUPLING LIKELY... AND FORECAST SOUNDINGS ARE SUFFICIENTLY DRY FOR CLEAR SKIES AND GOOD RADIATIONAL COOLING. WITH THICKNESSES DROPPING TO UNDER 1325 M OVER MUCH OF THE AREA THU NIGHT... EXPECT CHILLY LOWS FROM 36-42... WITH THESE COOLER READINGS IN THE RURAL OUTLYING AREAS. LOW DEWPOINTS SHOULD LIMIT THE FORMATION OF FROST... HOWEVER WILL TAKE A CLOSER LOOK AT THIS IN LATER FORECASTS. BUT AT THIS TIME IT LOOKS LIKE THIS WOULDN`T BE A WIDESPREAD EVENT ANYWAY. -GIH && .SHORT TERM /FRIDAY THROUGH SATURDAY/... AS OF 315 PM WEDNESDAY... FRIDAY... S/W RIDGE OVER THE CENTRAL U.S. AND A DEEP LOW PRESSURE SYSTEM OVER NORTHERN NEW ENGLAND WILL MAINTAIN A NW FLOW ALOFT OVER CENTRAL NC. AT THE SURFACE...AN AREA OF HIGH PRESSURE WILL EXTEND ACROSS THE FORECAST AREA. THIS SET-UP WILL PROVIDE FOR MOSTLY SUNNY/PARTLY CLOUDY SKIES AND TEMPS A FEW DEGREES BELOW NORMAL. HIGH TEMPS FRIDAY MID 60S FAR NORTH-NW TO NEAR 70 FAR SOUTH-SE. FRIDAY NIGHT AND SATURDAY...A S/W IN THE SOUTHERN STREAM WILL ADVANCE EAST FROM THE SOUTHERN PLAINS...AND THROUGH THE LOWER MS VALLEY LATE FRIDAY AND FRIDAY NIGHT. AS THIS SYSTEM APPROACHES THE CONFLUENT NW FLOW OVER OUR AREA...THE S/W WILL GRADUALLY WEAKEN. STILL...THIS SYSTEM WILL ADVECT ENOUGH MOISTURE INTO CENTRAL NC WHILE SPEED CONVERGENCE AT 700MB ALONG WITH WARM AIR ADVECTION AT 850MB WILL SUPPLY THE LIFT TO CAUSE SCATTERED TO NUMEROUS SHOWERS TO DEVELOP. BASED ON MODEL TIMING...SHOULD SEE MOSTLY CLEAR-PARTLY CLOUDY SKIES FRIDAY EVENING GIVE WAY TO MOSTLY CLOUDY -OVERCAST SKIES BY DAYBREAK SATURDAY. CANNOT RULE OUT A STRAY SHOWER ALONG OUR WESTERN FRINGE BY DAYBREAK SATURDAY BUT PROBABILITY APPEARS TOO LOW AT THIS TIME TO MENTION IN THE FORECAST. AFTER 12Z...SHOWERS DEVELOP IN THE MORNING HOURS ACROSS THE SOUTHERN-WESTERN PIEDMONT...OVERSPREADING THE REMAINDER OF CENTRAL NC SATURDAY AFTERNOON. MIN TEMPS FRIDAY NIGHT WILL BE MORE MILD COMPARED TO THE PREVIOUS NIGHT`S LOW TEMPS DUE TO THE INCREASING/THICKENING CLOUD COVER. MIN TEMPS NEAR 40/LOWER 40S FAR NE TO THE LOWER 50S FAR SOUTH-SW. OVERCAST SKIES AND INCREASING SHOWER COVERAGE WILL LEAD TO MUCH COOLER AFTERNOON TEMPS. HIGHS SATURDAY NEAR 60 FAR NORTH-NW TO THE MID-UPPER 60S SOUTH. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 315 PM WEDNESDAY... SATURDAY NIGHT-SUNDAY...THE SOUTHERN STREAM S/W WILL GRADUALLY WEAKEN AS IT MOVES EAST ACROSS THE SOUTHEAST U.S. SATURDAY NIGHT. THIS SYSTEM WILL MAINTAIN A THREAT FOR SHOWERS...ESPECIALLY DURING THE EVENING HOURS. SHOWER CHANCES SHOULD DECREASE LATE SATURDAY NIGHT-EARLY SUNDAY. A SECOND S/W...THIS ONE IN THE NORTHERN STREAM...WILL TRACK EAST-SE ACROSS THE CENTRAL APPALACHAINS INTO CENTRAL NC SUNDAY. THIS SYSTEM INTERACTING WITH AVAILABLE MOISTURE WILL SPARK A FEW SHOWERS...SPECIALLY DURING THE AFTERNOON-EARLY EVENING HOURS. COOLER THAN NORMAL TEMPERATURES WILL CONTINUE SUNDAY. MIN TEMPS SATURDAY NIGHT 45-50 NORTH...AND 50-54 SOUTH. HIGH TEMPS MID-UPPER 60S SUNDAY. MONDAY THROUGH WEDNESDAY... THE WEATHER PATTERN WILL REMAIN UNSETTLED THIS PERIOD. A WEAK HIGH PRESSURE SYSTEM WILL SETTLE INTO OUR REGION MONDAY IN THE WAKE OF THE EXITING NORTHERN STREAM S/W. A DEEP LOW PRESSURE OVER THE SOUTHERN PLAINS WILL DRIFT SLOWLY EAST TUESDAY INTO WEDNESDAY. AS THE SFC HIGH OVER OUR REGION MONDAY DRIFTS EAST TUESDAY...LOW LEVEL RETURN SLY FLOW WILL INCREASE MOISTURE OVER CENTRAL NC. THE APPROACH OF DISTURBANCES ROTATING OUT OF THE DEEP LOW WILL INCREASE THE THREAT FOR SHOWERS ACROSS THE CAROLINAS LATE TUESDAY INTO WEDNESDAY. HIGH TEMPERATURES THROUGH THIS PERIOD WILL AVERAGE 4-8 DEGREES BELOW NORMAL. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 730 PM WEDNESDAY... 24 HOUR TAF PERIOD: VFR CONDITIONS HOLDING AS DRY LOW LEVEL AIRMASS WITH SURFACE DEWPOINT DEPRESSIONS IN THE MID 30S PERSISTS OVER CENTRAL NC. COLD FRONT IS BEGINNING TO MOVE THROUGH THE CWA WITH KINT AND KGSO ALREADY REGISTERING NORTHWESTERLY WINDS. THREE EASTERN SITES STILL OBSERVING SOUTHWESTERLIES WITH SHIFT TO NORTHWESTERLIES AT KRDU AND KRWI EXPECTED JUST AFTER 6Z WITH KFAY CLOSER TO 9Z. FRONT WILL PASS AS A DRY FRONT WITH A FEW ELEVATED SHOWERS POSSIBLE. SOME POSSIBLE BROKEN TO OVERCAST CEILINGS BETWEEN 5-10 KFT ARE POSSIBLE AT THESE SITES WITH THE FRONTAL PASSAGE BUT WONT GO ANY LOWER THAN THAT. FOR THURSDAY EXPECT SOME GUSTY WINDS UP TO 20 KTS OUT OF THE WNW DURING THE LATE MORNING THROUGH THE AFTERNOON HOURS BUT NOT AS WINDY AS THIS AFTERNOON. SCATTERED CLOUDS POSSIBLE AT ABOUT 8 KFT AND AGAIN AT 25 KFT. LONG TERM: VFR CONDITIONS SHOULD HOLD THROUGH THE REMAINDER OF THE WORK WEEK BUT AN APPROACHING SYSTEM WILL PRESENT ADVERSE AVIATION CONDITIONS FOR AT LEAST SATURDAY AND POSSIBLY THROUGH SUNDAY. CONDITIONS AS LOW AS IFR ARE EXPECTED BEFORE A RETURN TO VFR FOR MONDAY. && .FIRE WEATHER... AS OF 250 PM WEDNESDAY... WILL MAINTAIN THE INCREASED FIRE DANGER THROUGH THE REST OF THE DAY. RECENT RAINFALL HAS ALLOWED FOR MOISTENING OF FINE FUELS OVER MUCH OF THE AREA... BUT WITH TODAY`S WIND SPEEDS SUSTAINED AS HIGH AS 10- 20 KTS GUSTING UP TO AROUND 30 KTS... AND RH VALUES BOTTOMING OUT IN THE 25-29% RANGE... DRYING OF TOP-LAYER FUELS SHOULD CONTINUE TODAY... AND OUTDOOR BURNING IS NOT ADVISED THROUGH SUNDOWN. A COOL DRY AIR MASS WILL OVERSPREAD CENTRAL NC OVERNIGHT AND PERSIST INTO THURSDAY. MIN RH VALUES MID-LATER AFTERNOON THURSDAY WILL DIP INTO THE 22-27 PERCENT RANGE. SFC WINDS WILL ALSO BE BREEZY WITH GUSTS 15-20 MPH LIKELY IN THE AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/HARTFIELD NEAR TERM...BSD/HARTFIELD SHORT TERM...WSS LONG TERM...WSS AVIATION...ELLIS FIRE WEATHER...DJF/HARTFIELD

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