Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 240737 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 335 AM EDT FRI APR 24 2015 .SYNOPSIS...COOL HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE NORTHWEST TODAY. A WARM FRONT WILL MOVE IN FROM THE SOUTHWEST LATE TONIGHT...AND THEN STALL ACROSS THE REGION THROUGH THE WEEKEND... BRINGING UNSETTLED WEATHER AS WAVES OF LOW PRESSURE TRACKING EAST ALONG THE FRONT. && .NEAR TERM /THROUGH TODAY/...
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AS OF 325 AM FRIDAY... HIGH PRESSURE OVER THE OHIO VALLEY...SITUATED BETWEEN AN UPPER LOW WOBBLING OVER EASTERN CANADA AND A SHORTWAVE RIDGE OVER THE DEEP SOUTH...WILL INCH EASTWARD THIS MORNING AND THEN BECOME ELONGATED OVER THE REGION THIS AFTERNOON AS A PIECE OF THE HIGH SETTLES OFF THE SOUTHEAST COAST. MORNING THICKNESSES BELOW 1320M SUGGEST HIGHS A COUPLE DEGREES COOLER THAN THURSDAY UNDER FULL SUN...65-71 NORTHEAST TO SOUTHWEST.
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&& .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
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AS OF 325 AM FRIDAY... A PLUME OF PACIFIC MOISTURE CROSSING MEXICO WILL BE DRAWN EASTWARD TODAY AS A WEAK UPPER LOW NEAR THE CA/AZ BORDER AREA OPENS UP AND LIFTS ACROSS THE PLAINS STATES. THE ASSOCIATED SURFACE WILL MOVE INTO THE MID-MISSISSIPPI RIVER VALLEY WHILE THE ATTENDANT WARM FRONT LIFTS THROUGH THE SOUTHEAST US. MID-CLOUDS WILL THICKEN FROM WEST TO EAST FRIDAY NIGHT AS WARM ADVECTION SPREADS ACROSS THE REGION....RESULTING IN LOWS RANGING FROM THE LOW 40S IN THE CLEARER EASTERN AREAS AND UPPER 40S TO AROUND 50 IN THE OVERCAST WESTERN AREAS. SOME AREAS OF LIGHT RAIN MAY REACH THE WESTERN PIEDMONT PRIOR TO 12Z SATURDAY...BUT THE MORE INTENSE 290-300K LAYER ISENTROPIC ASCENT IS PROGGED TO COME DURING THE DAY ON SATURDAY...AND MORE SO DURING THE AFTERNOON...AS THE SURFACE LOW MOVES TOWARD THE LOWER OHIO VALLEY REGION. A BAND OF RAIN DURING THE DAY SHOULD LOCK IN A COLD POOL OVER CENTRAL NC AND KEEP THE WARM FRONT DRAPED ACROSS THE SOUTHERN PORTIONS OF THE AREA...WHERE THE PROSPECTS OF SOME WEAK DESTABILIZATION...MAINLY ELEVATED...WILL BE GREATEST DURING THE LATE AFTERNOON AND EVENING HOURS BASED ON THE PREFERRED NAM AND ECMWF SOLUTIONS. WILL TRANSITION THE CHARACTER OF PRECIP IN THE FORECAST FROM RAIN TO SHOWERS DURING THE LATER AFTERNOON...WITH A SLIGHT CHANCE OF THUNDER FROM THE SOUTHERN PIEDMONT TO THE SANDHILLS DURING THE EVENING. WHILE MODELS STILL SHOW SOME DIFFERENCES IN QPF AMOUNTS...THE ECMWF AND SREF SHOW WHAT SEEMS TO BE THE MORE REASONABLE DISTRIBUTIONS...WITH THE HIGHER AMOUNTS AROUND A THIRD OF AN INCH ACROSS THE SOUTH AND LIGHTER AMOUNTS TO THE NORTH. TEMPS ARE TRICKY FOR SATURDAY AND WILL DEPEND ON THE TIMING OF PRECIP DURING THE FIRST HALF OF SATURDAY. HAVE SLOWED THE ARRIVAL OF PRECIP A LITTLE IN THE EAST...SO WILL NUDGE TEMPS UP OVER THE COASTAL PLAIN...BUT STILL EXPECT A STRONG GRADIENT FROM LOWER 50S NORTHWEST TO LOWER 60S SOUTHEAST. THERE SHOULD THEN BE A DECREASE IN SHOWER ACTIVITY SATURDAY NIGHT AS A DRY SLOT SURGES IN FROM THE WEST AND THE SURFACE LOW TRANSITIONS OFFSHORE. EXPECT SKIES TO REMAIN OVERCAST...HOWEVER...AND TEMPS WILL ONLY FALL A FEW DEGREES INTO THE UPPER 40S TO MID 50S.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 305 PM THURSDAY... SHORTWAVE AND ATTENDANT SURFACE LOW OVER THE MIDWEST ON SATURDAY WILL MOVE SOUTHEASTWARD OVER THE AREA ON SUNDAY... AROUND THE BASE OF BROAD CYCLONIC FLOW ASSOCIATED WITH AN UPPER LEVEL LOW OVER THE NORTHEAST. RAIN CHANCES WILL INCREASE THROUGH THE DAY SATURDAY WITH ISENTROPIC LIFT IN ADVANCE OF THE SYSTEM... AND PWS CLIMBING TO 1.5 INCHES. PRECIPITATION WILL TAPER OFF TO SCATTERED SHOWERS SUNDAY AFTERNOON... AS A COASTAL LOW DEVELOPS AND MOVES EASTWARD INTO THE ATLANTIC. TEMPERATURES WILL REMAIN BELOW NORMAL MONDAY AND TUESDAY... AS THE AREA REMAINS IN NORTHWEST FLOW UNDER THE INFLUENCE OF THE UPPER LEVEL LOW OVER NEW ENGLAND... AND WEAK HIGH PRESSURE BUILDS IN AT THE SURFACE. THE NEXT SYSTEM OF INTEREST WILL APPROACH THE AREA ON WEDNESDAY... AS AN UPPER LEVEL LOW OVER THE SOUTHWEST MOVES EASTWARD... OPENING INTO AN UPPER WAVE AS IT APPROACHES THE AREA... LIKELY INDUCING SURFACE WAVE DEVELOPMENT OVER THE GULF COAST. SUPPRESSED SOLUTION SHOWN BY THE 00Z ECMWF HAS BEEN DISCOUNTED BY WPC AS AN OUTLIER... SO WILL CONTINUE WITH CHANCE POPS GIVEN A TRACK ALONG THE GULF COAST... AND THEN ALONG THE SOUTHEAST COAST... SUPPORTED BY THE 12Z GFS/12Z GEFS MEAN/12Z ECMWF. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 150 AM FRIDAY... HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE NEXT 24 HOURS...WITH SUB-VFR CONDITIONS TO FOLLOW. RELATIVELY LIGHT NORTH-NORTHWESTERLY WINDS WILL CONTINUE FOR MOST AREAS THIS MORNING...INCREASING TO AROUND 10KT TODAY AS HIGH PRESSURE OVER THE OHIO VALLEY REGION BUILDS EAST. MOSTLY CLEAR SKIES WILL SLOWLY GIVE WAY TO HIGH CLOUDS FROM THE SOUTHWEST THIS EVENING AND THEN MORE MID CLOUDS BETWEEN 7-10K FT OVERNIGHT. OUTLOOK... THE APPROACH OF A WARM FRONT AND LOW PRESSURE SYSTEM WILL BRING WIDESPREAD RAIN AND MVFR/IFR CEILINGS SATURDAY AND SATURDAY NIGHT. LOW CEILINGS ARE EXPECTED TO LINGER INTO SUNDAY... WITH A GRADUAL IMPROVEMENT EXPECTED SUNDAY AFTERNOON. VFR CONDITIONS SHOULD RETURN BY MONDAY AND PERSIST INTO TUESDAY AS WEAK HIGH PRESSURE BUILDS INTO OUR REGION FROM THE NORTH-NW. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...22 SHORT TERM...22 LONG TERM...SEC AVIATION...22

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