Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 041507 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1006 AM EST WED MAR 4 2015 .SYNOPSIS...
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STRONG SOUTHWESTERLY FLOW WILL ADVECT WARM AIR INTO THE REGION...IN ADVANCE OF A STRONG COLD FRONT SETTLING SLOWLY SOUTHWARD INTO TN VALLEY AND MID-ATLANTIC STATES. THIS FRONT WILL MOVE SOUTH INTO THE AREA LATE TONIGHT THROUGH EARLY THURSDAY. COLD ARCTIC HIGH PRESSURE WILL BUILD OVER THE REGION BEHIND THE FRONT FOR FRIDAY AND SATURDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1006 AM WEDNESDAY... ...DENSE FOG ADVISORY THROUGH NOON TODAY... VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOWING BEGINNING STAGES OF CAD EROSION ALONG ITS WESTERN AND EASTERN FLANKS VIA SURFACE WARM FRONT AND STRONG SWLY FLOW ALOFT/MIXING ...HIGHLIGHTED BY A 65 KT LLJ AOA 2-3KFT. THE HIGHER ELEVATIONS IN THE NC MOUNTAINS...VERTICALLY CENTERED IN THE WARM AIR ALOFT...HAVE TEMPERATURES ALREADY IN THE MID 60S WITH DEWPOINTS IN THE UPPER 50S/NEAR 60. AIDED BY INCREASING INTERVALS OF SUNSHINE BY THE AFTERNOON AND THE HIGHER SOLAR SUN ANGLE...CENTRAL NC WILL BECOME OVERWHELMED BY THE WARM SECTOR BY THE AFTERNOON WITH BY AFTERNOON...WITH AFTERNOON TEMPERATURES INTO THE 70S(LOWER 70 NW TO MID 70 SE...ALONG WITH A GUSTY SW WIND AT 15-25 MPH WITH GUSTS TO 30- 35 MPH. FORCING IS ABSENT UNTIL THE ARRIVAL OF THE BACK-DOOR COLD FRONT LATE TONIGHT WITH WEAK DESTABILIZATION 100-200 J/KG CONFINED TO THE COASTAL PLAIN...SO EXPECT DRY CONDITIONS. TONIGHT...MODELS ARE AGAIN IN GENERAL AGREEMENT IN THE TIMING OF FRONT LATER TONIGHT AND EARLY THURSDAY. THIS OCCURS AS AN INITIAL WAVE OF LOW PRESSURE TRACKS FROM WESTERN NC INTO VA BETWEEN 06Z- 12Z...WHICH WILL PULL THE FRONT SOUTH THROUGH NC AFTER THE WAVE PASSES. THE COLDEST ADVECTION SHOULD LAG THE FROPA BY 3-6 HOURS WHICH WILL BE CRITICAL TO THE PRECIPITATION FORECAST FOR THURSDAY. EXPECT RAIN TO DEVELOP OVER MUCH OF WESTERN AND NORTHERN SECTIONS OF CENTRAL NC BEHIND THE FRONT LATE TONIGHT. INCREASING CLOUDINESS IN THE SOUTHEAST AHEAD OF THE FRONT. LOWS WILL ONLY BE IN THE 50S AND 60S NORTH TO SOUTH...WITH THE MAIN TEMPERATURE FALL EXPECTED AFTER 12Z. INCREASING RAIN AND A NE FLOW WILL SPREAD IN BEHIND THE FRONT MAKING THE MORNING WAIT AT THE BUS STOP RATHER MISERABLE IN THE TRIAD AND TRIANGLE...LESS SO IN FAYETTEVILLE AND LAURINBURG... ONLY TO ARRIVE TOWARD MID TO LATE MORNING.
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... AS OF 255 AM WEDNESDAY... THE CURRENT MODEL PROJECTIONS ARE ESSENTIALLY NEARLY IDENTICAL TO THE PREVIOUS RUN AND FORECAST PACKAGE FOR THE PREDOMINATE P-TYPE, QPF, AND TEMPERATURES FOR THURSDAY INTO THURSDAY NIGHT. THE SPRAWLING ARCTIC PARENT HIGH PRESSURE CENTER WILL START THE DAY FAR REMOVED FROM CENTRAL NC... OVER IOWA (1040 MB). THE COLDEST AIR WILL INITIALLY BE BLOCKED BY THE APPALACHIAN PEAKS OF VA/NC... BUT THE COLD AIR WILL SURGE SOUTH THROUGH MD AND VA INTO NC DURING THE LATE MORNING AND AFTERNOON... THEN INTO THE SOUTHERN NC COUNTIES LATE THURSDAY AFTERNOON. RAIN IS EXPECTED TO BE WIDESPREAD IN THE ANAFRONT FASHION WITH A SW JET ALOFT RIDING UP AND OVER THE INCREASINGLY COLD NE FLOW NEAR THE SURFACE. THE FINAL WAVE ALONG THE FRONT WILL ENHANCE LIFT AND CONVERGENCE ACROSS THE REGION AS IT TRACKS FROM THE SOUTHERN APPALACHIANS TO OFFSHORE OF SC/SOUTHERN NC BY 00Z/FRI. PARTIAL THICKNESSES SUGGEST THAT A GRADUAL MIX WITH OR CHANGEOVER TO FREEZING RAIN SHOULD OCCUR ALONG THE NC/VA BORDER BY MID AFTERNOON AS THE SURFACE TEMPERATURES AND DEW POINTS PLUNGE TO 32. WE WILL TRY TO PLACE THE CHANGE OVER TIMING WITH THE LATEST FORECAST WET BULB TEMPERATURE FORECASTS OFF A BLEND OF THE SREF AND OPERATIONAL MODELS. THIS GRADUAL CHANGEOVER TO FREEZING RAIN... POSSIBLY MIXED WITH A LITTLE SLEET WILL SLOWLY PUSH SOUTH AND WEST TOWARD THE TRIAD AND TRIANGLE AREAS AND THE ROCKY MOUNT AND WILSON AREAS... BETWEEN 400 AND 700 PM. KEEP IN MIND THAT FOR THE FREEZING RAIN TO ACTUALLY BEGIN TO BECOME A HAZARD WILL TAKE LONGER THAN IN RECENT COLD STORMS...DUE TO THE WARM GROUND... TIMING OF THE CHANGEOVER (LATE AFTERNOON)...AND THE INCREASING SOLAR INSOLATION. IN ADDITION... THE WARM NOSE ALOFT IS FORECAST TO LINGER THROUGH ALL BUT THE LAST GASPS OF THIS SYSTEM`S PRECIPITATION. THEREFORE...A WARM WET GROUND...LITTLE "FROZEN" PRECIPITATION...AND TIME OF DAY SHOULD PREVENT ALL BUT POSSIBLY THE NORTHERN TIER OR TWO OF COUNTIES FROM HAVING FREEZING RAIN TO ACCRUE. EVEN THERE...IT SHOULD BE ONLY SEVERAL HOURS IN WHICH THE ACCRUAL WOULD BE LIMITED TO ELEVATED SURFACES. THE REAL WEATHER HAZARD AS FAR AS ICE MAY NOT OCCUR UNTIL THE PRECIPITATION ENDS THURSDAY EVENING. THIS IS WHEN THE TEMPERATURES WILL REALLY FALL WITH STRONG CAA FROM THE NORTH AND CLEARING SKIES LEADING TO TEMPERATURES QUICKLY FALLING THROUGH THE 20S. A WINTER WEATHER ADVISORY FOR ICE OR BLACK ICE MAY BE NEEDED ESPECIALLY ALONG AND NORTH OF THE TRIAD AND TRIANGLE AREAS TO WILSON AND ROCKY MOUNT FOR THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 245 AM WEDNESDAY... FRI/FRI NIGHT: COLD ADVECTION ATTENDANT ~1040 MB ARCTIC HIGH PRESSURE BUILDING INTO THE CAROLINAS FROM THE N/NW DURING THE DAY WILL RESULT IN WELL...WELL BELOW NORMAL TEMPERATURES (AS MUCH AS 25- 30 DEGREES) ON FRIDAY...WITH THE LATEST 00Z GFS/ECMWF SUGGESTING HIGHS RANGING FROM THE UPPER 20S TO LOWER 30S IN THE NE COASTAL PLAIN TO LOW/MID 30S WEST/SW PIEDMONT. GIVEN CLEAR SKIES AND EARLY MARCH INSOLATION...WILL REDUCE HIGHS SEVERAL DEGREES FROM THE PRIOR FORECAST...REMAINING SEVERAL DEGREES ABOVE WHAT GUIDANCE ALONE WOULD SUGGEST. LOWS FRI NIGHT IN THE UPPER TEENS NORTHEAST TO LOW/MID 20S SOUTHWEST. SAT-SUN NIGHT: UNIDIRECTIONAL FLOW ALOFT /DRY CONDITIONS/ AND MOSTLY CLEAR SKIES ARE EXPECTED TO PREVAIL ACROSS THE REGION THROUGH THE WEEKEND...WITH NORTHERN STREAM SHORTWAVE ENERGY CONFINED TO THE GREAT LAKES /NEW ENGLAND/ AND SOUTHERN STREAM SHORTWAVE ENERGY CONFINED TO THE DESERT SW AND WESTERN GOMEX. EXPECT MODERATING TEMPS...THOUGH STILL BELOW NORMAL...WITH HIGHS GENERALLY IN THE 50S SAT/SUN AND LOWS RANGING FROM THE LOWER 30S SAT NIGHT TO MID/UPPER 30S SUN NIGHT WHEN MID/UPPER LEVEL CLOUD COVER IS PROGGED TO INCREASE AS SOUTHERN STREAM SHORTWAVE ENERGY...ATTENDANT WAA/FGEN...AND RESULTING PRECIPITATION PROGRESS EASTWARD ALONG THE GULF COAST. MON-TUE: GIVEN A SPLIT FLOW SYNOPTIC PATTERN...CONFIDENCE IN FORECAST DETAILS DECREASES DRAMATICALLY BY EARLY NEXT WEEK... PARTICULARLY WITH REGARD TO THE EVOLUTION OF SOUTHERN STREAM SHORTWAVE ENERGY PROGRESSING EAST ALONG THE GULF COAST. AT THIS TIME...WILL STEER THE FORECAST CLOSE TO CLIMATOLOGY. -VINCENT && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 1230 AM WEDNESDAY... LIFR CEILINGS WILL WORSEN THROUGH THE NIGHT AS VISIBILITIES LOWER AS WELL. AREAS OF DENSE FOG ARE LIKELY TO DEVELOP OVERNIGHT OR EARLY WED...AS WARM AND MOIST AIR IS FORCED ATOP A COLD...SATURATED...AND VERY STABLE LAYER OF AIR NEAR THE SURFACE. CONDITIONS WILL TRANSITION UP BRIEFLY THROUGH IFR-MVFR RANGE...BEFORE LIKELY SCATTERING OUT TO VFR ALTOGETHER...AS THE WARM FRONT AT THE SURFACE FINALLY MAKES INROADS ACROSS CENTRAL NC DURING THE MIDDAY-EARLY AFTERNOON HOURS AT EASTERN TAF SITES...TO MID-LATE AFTERNOON (IF AT ALL) AT KINT/KGSO. ANOTHER ISSUE AFTER THE LOW CIGS AND VSBYS LIFT WILL BE THE INCREASING SW WINDS AT 15-25KT WITH GUSTS TO 30KT BETWEEN 15Z-23Z. THEN A COLD FRONT AND ASSOCIATED AREA OF RAIN AND SUB-VFR CONDITIONS ARRIVE FROM THE NORTHWEST WED NIGHT...AND PERSIST THROUGH THU. A BRIEF MIX OF SLEET AND/OR FREEZING RAIN WILL BE POSSIBLE BEFORE PRECIPITATION ENDS LATE THU OR THU EVENING AT KGSO KINT AND KRDU. OUTLOOK FOR THURSDAY NIGHT INTO SATURDAY: VFR CONDITIONS UNDER HIGH PRESSURE. && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR NCZ007>011-021>028- 038>043-073>078-083>086-088-089. && $$ SYNOPSIS...BADGETT NEAR TERM...CBL SHORT TERM...BADGETT LONG TERM...VINCENT AVIATION...BADGETT

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