Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261846 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 PM EDT SUN APR 26 2015 .SYNOPSIS...A WEAK AREA OF HIGH PRESSURE WILL BUILD INTO CENTRAL NC TONIGHT AND MONDAY...AND SETTLE OVERHEAD MONDAY NIGHT INTO TUESDAY. AN AREA OF LOW PRESSURE WILL BEGIN TO AFFECT OUR REGION TUESDAY NIGHT AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 245 PM SUNDAY... MAIN FORECAST CHALLENGE IN THE NEAR TERM CENTERS ON WHEN SKIES ARE EXPECTED TO CLEAR. VISIBLE IMAGERY DOES SHOW A SOUTHWARD DRIFT TO THE CLEARING-OUT OF THE LOW CLOUDS OVER CENTRAL-SOUTHEAST VA EARLY THIS AFTERNOON. THIS SURGE OF DRIER AIR IS OCCURRING IN THE WAKE OF THE PASSAGE OF THE 850MB TROUGH. THIS FEATURE CURRENTLY DRIFTING SOUTH OVER CENTRAL NC (IN VICINITY OF HIGHWAY 64). MODEL GUIDANCE SUGGEST LOW CLOUDS DEPARTING NORTH-SOUTH BETWEEN 21Z-02Z. WILL LEAN FORECAST IN THIS DIRECTION. HOWEVER...POTENTIAL FOR THE OVERCAST/BROKEN SKIES TO PERSIST A BIT LONGER THAN FORECAST AS LOSS OF INSOLATION MAY SLOW CLOUD EROSION PROCESS. OTHERWISE MAY SEE A FEW PATCHES OF RAIN WITH THE PASSAGE OF THE 850MB TROUGH OVER THE SOUTHERN COUNTIES LATE THIS AFTERNOON-EARLY EVENING. COVERAGE EXPECTED TO BE ISOLATED AND OBSERVED AMOUNTS WILL TOTAL NO MORE THAN A TRACE OR A HUNDREDTH. A LIGHT NLY WIND THIS EVENING WILL SUBSIDE TO NEAR CALM OVERNIGHT. IF PARTIAL CLEARING OCCURS...POTENTIAL FOR POCKETS OF FOG TO DEVELOP. MIN TEMPS LOW-MID 40S. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 245 PM SUNDAY... MONDAY...A MINOR S/W WILL CROSS THE NORTHERN MID ATLANTIC MONDAY...BRUSHING NE NC IN THE LATE AFTERNOON. THIS FEATURE WILL LIKELY ENHANCE STRATOCU COVERAGE OVER THE NORTHERN COASTAL PLAIN WITH AN ISOLATED PATCH OF LIGHT RAIN POSSIBLE. ELSEWHERE THE SUN WILL MAKE AN APPEARANCE. A STEADY NW LOW LEVEL FLOW WILL AID TO DIMINISH ANY LINGERING LOW CLOUD COVER OVER THE REST OF THE PIEDMONT AND SANDHILLS. TEMPERATURES WILL RECOVER NICELY IN THIS DOWNSLOPE WIND REGIME. AFTERNOON TEMPS WILL VARY FROM THE MID-UPPER 60S IN THE PIEDMONT/NORTHERN COASTAL PLAIN TO AROUND 70 IN THE SE. MONDAY NIGHT...NOSE OF SFC RIDGE WILL EXTEND ACROSS THE REGION. DRY AIR UNDERNEATH THIS RIDGE WILL RESULT IN MOSTLY CLEAR SKIES. MIN TEMPS WILL BE CHILLY..DIPPING INTO THE UPPER 30S AND LOWER 40S. AT THIS TIME...NOT EXPECTING TEMPS TO DIP BELOW 37 DEGREES. THUS PATCHY LIGHT FROST NOT A CONCERN...BUT WILL CONTINUE TO MONITOR. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 405 AM SUNDAY... THE MODELS ARE COMING INTO BETTER AGREEMENT REGARDING THE EASTWARD- SHEARING/DEAMPLIFICATION OF AN INITIALLY CLOSED LOW OVER THE SW US AND CONCURRENT A AMPLIFICATION OF A NORTHERN STREAM SHORTWAVE TROUGH FROM NW CANADA TO THE MID-MS VALLEY...ALL ON THE WESTERN PERIPHERY OF A DEEP VORTEX OFF THE NEW ENGLAND COAST. MODEL SPREAD INCREASES THROUGH THE END OF THE WEEK...HOWEVER...AS THE MODELS CONTINUE TO HAVE A DIFFICULT TIME RESOLVING THE AMPLIFICATION OF ADDITIONAL NORTHERN STREAM SHORTWAVE ENERGY INTO AN EASTERN CONUS TROUGH...AND HOW THIS ENERGY ULTIMATELY INTERACTS WITH THE LEAD WAVES. THE MODELS ARE IN SIMILARLY GOOD AGREEMENT AT THE SURFACE REGARDING THE DEVELOPMENT OF SURFACE LOW ALONG THE GULF COAST TO NEAR SAVANNAH GA BY 00Z THU...WITH INCREASING MODEL SPREAD/DECREASING FORECAST CONFIDENCE REGARDING THE TRACK AND TIMING OF THE LOW INTO THE WESTERN ATLANTIC. WILL FOLLOW WPC PREFERENCE TOWARD A SLOWER SOLUTION ON THE WESTERN EDGE OF THE MODEL SPREAD...WITH A SUSPICION THAT THE TRAILING NORTHERN STREAM WILL HELP DRAW THE CYCLONE WEST/CLOSER TO THE COAST AS IT LIFTS UP THE MIDDLE ATLANTIC COAST THROUGH THU. THE SENSIBLE WEATHER AFFECTS WILL BE A WARM AND DRY TUE...WITH TEMPERATURES IN THE MIDDLE 60S TO AROUND 70 DEGREES...FOLLOWED BY RAIN DEVELOPING/SPREADING NORTHEAST INTO CENTRAL NC LATE TUE NIGHT OVER THE SOUTHERN PIEDMONT AND ACROSS THE REMAINDER OF THE CWFA THROUGH THE DAY WED. EVEN PRIOR TO THE ONSET OF RAIN WED...MID LEVEL OVERCAST SHOULD CAUSE TEMPERATURES TO REMAIN BELOW GUIDANCE - IN THE UPPER 50S TO LOWER 60S...WARMEST NE; AND EVEN THOSE TEMPERATURES MAY ULTIMATELY PROVE A CATEGORY TOO WARM IF THE OVERCAST AND RAIN INDEED MATERIALIZE AS EXPECTED. RAIN WOULD THEN TAPER OFF FROM WEST TO EAST WED NIGHT-THU...AND YIELD TO DRIER AND WARMER CONDITIONS FRI- SAT...WITH TEMPERATURES RETURNING TO NEAR AVERAGE LEVELS IN THE MIDDLE 70S TO AROUND 80 DEGREES BY SAT. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 125 PM SUNDAY... HIGH LIKELIHOOD THAT MVFR CONDITIONS WILL PERSIST THROUGH 21Z ACROSS CENTRAL NC. AFTER 21Z...NLY FLOW WILL BEGIN TO INFILTRATE A DRIER AIR MASS INTO THE LOWEST 5K FEET OF THE ATMOSPHERE WHICH SHOULD AID TO DIMINISH THE LOW STRATUS. THIS SHOULD LEAD TO VFR CONDITIONS ACROSS CENTRAL NC THIS EVENING. AFTER 03Z...WILL LIKELY SEE POCKETS OF IFR/LIFR FOG DEVELOP WHICH MAY AFFECT MOST IF NOT ALL TERMINALS AFTER 06Z. THE PATCHY OR AREAS OF FOG SHOULD LIFT/DISSIPATE BY 12Z. VFR CONDITIONS ANTICIPATED MONDAY INTO TUESDAY AS AN AREA OF HIGH PRESSURE WILL DOMINATE OUR WEATHER PATTERN. ASIDE FROM A BRIEF PERIOD OF MVFR FOG TUESDAY MORNING...VFR CONDITIONS SHOULD RULE. AN APPROACHING LOW PRESSURE SYSTEM WILL BRING A CHANCE OF SUB VFR CONDITIONS TO CENTRAL NC WEDNESDAY INTO THURSDAY. IMPROVING AVIATION CONDITIONS ARE ANTICIPATED THURSDAY NIGHT INTO FRIDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...RAH AVIATION...WSS

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