Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 251940 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 340 PM EDT WED MAR 25 2015 .SYNOPSIS...HIGH PRESSURE EXTENDING SOUTH OVER THE MID-ATLANTIC REGION WILL SHIFT OUT INTO THE ATLANTIC TODAY. THIS WILL ALLOW A WARM FRONT TO LIFT NORTH THROUGH THE STATE OVERNIGHT. A COLD FRONT WILL APPROACH SLOWLY FROM THE WEST ON THURSDAY AND WILL CROSS THE AREA THURSDAY NIGHT. && .NEAR TERM /TONIGHT/... AS OF 335 PM WEDNESDAY... STRONG INFLUX OF ATLANTIC MOISTURE WITHIN A STRENGTHENING H9 35-40KT SOUTHERLY LLJ WILL OVERSPREAD THE AREA OVERNIGHT... SUPPORTING SCATTER TO NUMEROUS SHOWERS AND POSSIBLY A RUMBLE OF THUNDER OR TWO AS AS WEAK INSTABILITY DEVELOPS(MUCAPE(400-600 J/KG)OWING TO STEEP MID-LVL LAPSE RATES OVER THE AREA. AS FAR AS SEVERE POTENTIAL...WHILE FAVORABLE EFFECTIVE SHEAR OF 35KTS COULD SUPPORT SOME ROTATION WITH THE STRONGER CELLS...THE ABSENCE OF FORCING OUTSIDE OF LOW-LEVEL WAA COUPLED WITH SHALLOW DEPTH OF MOISTURE WILL LIMIT SEVERE POTENTIAL. EXPECT NEAR STEADY TEMPS OVERNIGHT WITHIN THE LINGERING CAD WEDGE IN PLACE IN THE TRIAD...PERHAPS RISING A FEW DEGREES BY SUNRISE. ELSEWHERE...EXPECT LOWS IN THE LOWER TO MID 60S. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 335 PM WEDNESDAY... THURSDAY: OWING TO THE SLOWER ARRIVAL OF THE FRONT INTO THE AREA...NOW DELAYED UNTIL AFTER 00Z FRIDAY...ONCE CONVECTION EXITS THE COASTAL PLAIN THURSDAY MORNING...THURSDAY LOOKS TO BE MOSTLY DRY ACROSS CENTRAL NC. IT WILL BE MUCH WARMER AS WELL. AS LOW-LEVEL FLOWS TO VEER AROUND A MORE SWLY COMPONENT...DRIER AIR WILL ADVECT INTO THE AREA FROM THE SW WHICH WILL HELP TO SCOUR LINGERING LOW CLOUDS/MOISTURE AND YIELD PARTLY TO MOSTLY SUNNY CONDITIONS THURSDAY AFTERNOON. WARM SECTOR TEMPERATURES WILL RISE WELL INTO THE 70S ACROSS THE AREA...APPROACHING NEAR 80 ACROSS THE FAR SE ZONES. THURSDAY NIGHT: COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST BETWEEN 03 TO 12Z THURSDAY NIGHT/EARLY FRIDAY MORNING. CHANCE OF THUNDER LOOKS LOW APPEARS QUESTIONABLE GIVEN UNFAVORABLE DIURNAL TIMING AND LACK OF SUPPORT ALOFT AS THE AMPLIFYING UPPER LEVEL TROUGH IS PROGGED TO LAG BEHIND THE COLD FRONT. HOWEVER...BOTH THE GFS AND EC INDICATE THE POTENTIAL FOR WEAK DISTURBANCES IN ADVANCE OF THE MAIN TROUGH THAT COULD ENHANCE FORCING BETWEEN 00 TO 06Z ACROSS THE AREA WITH LINGERING STEEP MID-LEVEL LAPSE RATES AROUND 7.0 DEG/KM ACROSS THE WESTERN PIEDMONT. WILL INCLUDE A SLIGHT CHANCE OF THUNDER ACROSS THE NW PIEDMONT...WITH SHOWERS ELSEWHERE DUE TO WANING INSTABILITY AS THE FRONT CROSSES THE AREA. ANAFRONTAL PRECIP WILL THEN FILL IN BEHIND THE FRONT WITH THE APPROACH OF THE AMPLIFYING TROUGH INTO THE SOUTHERN APPALACHIANS AND ENSUING STRONG LOW-LEVEL CAA. LOWS RANGING FROM UPPER 40S/LOWER 50S NW TO NEAR 60S ACROSS THE SE DEPENDING ON THE EXACT TIMING OF THE COLD FRONT. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 340 PM WEDNESDAY... THE SURFACE COLD FRONT AND PRIMARY AREA OF SHOWERS ARE EXPECTED TO BE JUST EAST OF THE CWA BY 12Z FRIDAY....WHILE THE MAIN TROUGH AXIS LAGS WEST OF THE MOUNTAINS UNTIL FRIDAY EVENING. IN BETWEEN...LINGERING MOISTURE AND CONTINUED HEIGHT FALLS APPEAR TO BE ENOUGH FOR SOME ADDITIONAL ANAFROTNAL PRECIP THROUGH EARLY AFTERNOON...BEFORE MORE RESPECTABLE DRYING ALOFT MOVES IN FROM WEST TO EAST. LOW CONFIDENCE TEMP FORECAST AS TEMPS SHOULD INITIALLY BE FALLING THROUGH THE MORNING HOURS...WITH THE STRONGEST WARMING OVER THE WESTERN PIEDMONT DURING THE AFTERNOON IF CLOUDS CAN BREAK WITH THE DRYING ALOFT. USING A BLEND OF GUIDANCE GENERALLY YIELDS LOW TO MID 50S. THE PRIMARY TROUGH AXIS AND ASSOCIATED VORT CENTER WILL CROSS THE AREA FRIDAY NIGHT. AS TEMPS FALL THROUGH THE 40S AND INTO THE UPPER 30S...GFS FORECAST SOUNDINGS SHOW A BRIEF PERIOD OF STRONG OMEGA AND SUFFICIENT RESATURATION OF THE ICE-NUCLEATION ZONE FOR SHOWERS AFTER MIDNIGHT....FOCUSED MAINLY EAST OF THE TRIANGLE. SREF SOUNDINGS SHOW A WIDE VARIETY OF PROFILES AND THE ECMWF DOESNT HAVE MOISTURE QUITE A DEEP OVER THE COASTAL PLAIN. WITH A RELATIVELY SHALLOW ABOVE FREEZING LAYER NEAR THE SURFACE...ABOUT 2500 FT PER GFS SOUNDINGS...ITS POSSIBLE THAT RAIN SHOWERS COULD MIX WITH SOME SNOW AFTER MIDNIGHT...BUT WOULD LIKE TO SEE A LITTLE BETTER AGREEMENT IN MOISTURE PROFILES BEFORE INCLUDING ANY MENTION IN THE OFFICIAL FORECAST. LOWS IN THE LOWER 30S WEST TO UPPER 30S EAST. THE UPPER TROUGH WILL MOVE EAST AND HIGH PRESSURE BEGINS TO BUILD IN ON SATURDAY AND 1000-850MB THICKNESSES BOTTOM OUT IN THE 1270 TO 1280M RANGE. THE SURFACE HIGH IS FORECAST TO REMAIN JUST WEST OF THE MOUNTAINS...SO ONLY THE WESTERN PIEDMONT LOOKS TO HAVE A GOOD CHANCE OF DECOUPLING BY SUNDAY MORNING. THICKNESSES WOULD SUPPORT SUB-FREEZING LOWS FOR THE ENTIRE AREA AND EVEN MID 20S GIVEN MULTIPLE HOURS OF IDEAL RADIATIONAL COOLING. A WARMING TREND WILL THEN COMMENCE SUNDAY ONWARD AS HEIGHT BEGIN TO BUILD ALOFT AGAIN AND HIGH PRESSURE MOVES OFFSHORE. TEMPS ARE EXPECTED TO REBOUND BACK TO AND ABOVE NORMAL FOR THE FIRST HALF FO THE WEEK. ANOTHER COLD FRONT IS EXPECTED ON MONDAY...THOUGH WITH LIMITED MOISTURE AND ONLY A BRIEF COOL DOWN BEHIND IT. && .AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... AS OF 215 PM WEDNESDAY... 24-HR TAF PERIOD: AMIDST WEAK LOW-LEVEL WARM ADVECTION ATOP A SHALLOW COOL DRY SFC AIRMASS...KINT AND KGSO WILL MAINTAIN MVFR CEILINGS WITH A SLIGHT CHANCE OF LIGHT RAIN OR DRIZZLE THROUGH THE AFTERNOON. AT RWI/FAY...CEILINGS HAVE LIFTED TO VFR 5000-9000 FT AGL) AND SHOULD REMAIN THROUGH THE REMAINDER OF THE AFTERNOON. SADDLED IN BETWEEN...RDU WILL BE ON THE THRESHOLD OF HIGH-END MVFR/LOW END VFR WITH CEILINGS GENERALLY 2500-3500 KFT. CONDITIONS ARE EXPECTED TO DETERIORATE LATE THIS EVENING AND INTO THE OVERNIGHT HOURS AS STRONG WARM MOIST AIR ADVECTION WITHIN A A STRENGTHENING 35-40KT 925MB LOW-LEVEL JET OVERSPREADS THE AREA OVERNIGHT. EXPECT CEILINGS TO LOWER TO IFR AND PERHAPS LIFR OVERNIGHT WITH SCATTERED TO NUMEROUS SHOWERS AND POSSIBLY A THUNDERSTORM OR TWO POSSIBLE. ADDITIONALLY...AS THE LOW-LEVEL JET LIFTS ACROSS THE AREA...KINT AND KGSO MAY EXPERIENCE LLWS BETWEEN 03 TO 12Z AS CAD WEDGE MAY HOLD IN PLACE. WILL NOT INCLUDE ANY LLWS AT THIS TIME...BUT LLWS MAY BE ADDED WITH THE EVENING(00Z)PACKAGE. CEILINGS ARE EXPECTED TO IMPROVE TO VFR DURING THE DAY ON THURSDAY AS AS A WARM SECTOR BECOMES MORE FIRMLY ESTABLISHED AND DRIER AIR MOVES INTO THE AREA FROM THE SOUTHWEST. BREEZY SWLY WINDS OF 20 TO 25KTS ARE ALSO EXPECTED THURSDAY AFTERNOON. LOOKING AHEAD: A COLD FRONT WILL CROSS THE AREA THURSDAY NIGHT. SCATTERED SHOWERS ARE POSSIBLE AHEAD OF THE FRONT...BUT PRECIP WILL BE MOSTLY ANA-FRONTAL WITH CATEGORICAL RAIN CHANCES AND MVFR/IFR CEILINGS RETURNING EARLY FRI MORNING...PERSISTING THROUGH THE DAY AT EASTERN TERMINALS. THE RETURN OF VFR CONDITIONS LATE FRIDAY AFTERNOON/EVENING COULD BE TEMPORARILY DELAYED UNTIL THE PASSAGE OF THE STRONG UPPER LEVEL TROUGH SATURDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...CBL LONG TERM...22 AVIATION...CBL

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.