Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 231929 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 230 PM EST FRI JAN 23 2015 .SYNOPSIS...A LOW PRESSURE SYSTEM WILL TRACK NORTHEAST OVER THE EASTERN CAROLINA`S TONIGHT AND EARLY SATURDAY. THE MAIN COLD FRONT WILL PUSH THROUGH OUR REGION SATURDAY. ANOTHER COLD FRONT WILL APPROACH FROM THE NORTHWEST SUNDAY NIGHT AND EARLY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM FRIDAY... COLD RAINY WEATHER TONIGHT INTO EARLY SATURDAY... SURFACE HIGH PRESSURE CONTINUED TO RETREAT OFFSHORE THIS AFTERNOON AS LOW PRESSURE TRACKED ALONG THE GULF COAST STATES. RAIN BECAME WIDESPREAD ACROSS THE CAROLINA`S TODAY WITH SOME AREAS REPORTING A BRIEF MIXTURE OF SLEET AND RAIN AT THE PRECIPIATION ONSET FROM THE TRIAD TO ROXBORO. THE HIGH TO THE NORTH WAS RETREATING RAPIDLY OFFSHORE THIS MORNING WHICH QUICKLY CUT OFF ANY SOURCE OF COLD AIR INTO OUR REGION. INSTEAD... A SOUTHEAST TO SOUTH FLOW INCREASED JUST ABOVE THE SURFACE WITH RAPIDLY MOISTENING AND WARMING COLUMN OUT IN ADVANCE OF THE APPROACHING DEEP MID/UPPER TROUGH OVER THE LOWER MISSISSIPPI VALLEY. AS THIS TROUGH APPROACHES... THEN CROSSES OVER THE REGION TONIGHT... THE SURFACE LOW CURRENTLY DEVELOPING OVER THE FLORIDA PANHANDLE WILL TURN NORTHEAST ALONG THE COASTAL PLAIN OF GA/SC/NC OVERNIGHT. WITH SURFACE TEMPERATURES SAFELY ABOVE FREEZING AND WITH SATURATION IN PLACE AT THE SURFACE... AND EVEN CONTINUED WARMING ALOFT... PLAIN RAIN WILL CONTINUE TO BE DOMINATE OVER NC. THE TEMPERATURES SHOULD BE NEAR THE LOWS ALREADY THIS AFTERNOON (IN THE MID 30S)... WITH READINGS EXPECTED TO REMAIN STEADY OR SLOWLY RISE (ESPECIALLY ALONG I-95 OVERNIGHT). THE RELATIVELY FAST MOVEMENT OF THE LOW PRESSURE (REACHING NEAR ELIZABETH CITY BY 09Z/SAT) SHOULD COMBINE WITH THE STRONG IN-SITU COLD AIR DAMMING EVENT OVER THE PIEDMONT TO LIMIT THE WESTWARD OR INLAND PUSH OF THE COASTAL FRONT. TEMPS OVER THE COASTAL PLAIN MAY WELL RISE TO AROUND 50 LATE TONIGHT... WHILE READINGS REMAIN IN THE MID 30S OVER THE NW PIEDMONT. QPF MAY BE A BIT LESS THAN EARLIER ANTICIPATED AS THE DEEP CONVECTION CONTINUES TO BE ROLLING ALONG FROM THE GULF TO FLORIDA... HAVING SOME NEGATIVE IMPACT ON QPF INLAND. JUST HOW MUCH THIS AFFECTS OUR STORM TOTALS IS OF LOW CONFIDENCE. THE LATEST HRRR AND THE OPERATIONAL MODELS GENERALLY DEPICT ABOUT 1/3 LESS QPF THAN THE EARLIER 1-2 INCH FORECAST. WE WILL TREND A BIT LOWER - WHICH WOULD LESSEN THE RUNOFF POTENTIAL FOR OUR REGION - WHICH WAS NOT ANTICIPATED TO CREATE MAJOR PROBLEMS EVEN WITH 1-2 INCHES STORM TOTALS. THE HRRR... WHICH ACTUALLY VERIFIED WELL WITH P-TYPE AND TIMING TODAY... INDICATES THE MAIN BACK EDGE OF THE LARGE RAIN SHIELD MAY EDGE INTO THE SW PIEDMONT BY AT LEAST 06Z AND THE REST OF THE REGION BY 12Z/SAT. HOWEVER... THERE MAY BE ADDITIONAL "FILL IN" OF ANY DRY HOLES INLAND SC/NC IF/WHEN THE DEEP SOUTH/FLORIDA CONVECTION DISSIPATES. THE THUNDERSTORM THREAT IS MINIMAL OVER OUR REGION GIVEN THE TRACK OF THE LOW AROUND OR JUST EAST OF I-95... AS MOST OF THE REGION WILL REMAIN IN THE CAD REGION. THE HEAVIEST QPF AROUND 1 TO 1.5 INCHES IS STILL FORECAST OVER AND EAST OF THE TRIANGLE... WITH AMOUNTS LIKELY 0.50 TO 0.75 IN THE NW. -BADGETT && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 230 PM FRIDAY... THE MAIN RAIN EVENT WILL END BETWEEN 09Z/15Z SW TO NE ACROSS OUR REGION SATURDAY AS THE STORM BOMBS AS IT MOVES AWAY FROM DELMARVA. THE TRAILING DEFORMATION BAND OF PRECIPITATION WITH THE MID LEVEL LOW IS EXPECTED TO WEAKEN AND DISSIPATE AS IT SPREADS EAST FROM KY/TN/WVA INTO WESTERN VA AND NORTH-CENTRAL NC SATURDAY. IN ADDITION... THE BOUNDARY LAYER WINDS WILL SHIFT TO THE WNW AND INCREASE TO 10-20 MPH IN DOWNSLOPE FASHION DURING THE AFTERNOON. THIS SHOULD LEAD TO SHARP CLEARING FROM OFF THE BLUE RIDGE INTO THE PIEDMONT DURING THE AFTERNOON. SKIES SHOULD BECOME PARTLY SUNNY DOWN EAST LATE IN THE AFTERNOON. HIGHS SHOULD RETURN INTO THE 45-55 RANGE NW TO SE. THE SKIES SHOULD REMAIN MOSTLY CLEAR TO PARTLY CLOUDY SATURDAY NIGHT. LOWS 30-35 WITH DIMINISHING NW BREEZES IN THE EVENING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 345 AM FRIDAY... JUST AS QUICKLY AS THE CLOUDINESS AND SHOWERS ASSOCIATED WITH THE "ALBERTA CLIPPER"/NORTHERN STREAM SHORTWAVE WAVE MOVE OUT... ADDITIONAL SHEAR VORTICITY IN FAST NW FLOW ALOFT WILL AMPLIFY INTO THE TROUGH BASE...TO NEAR AND JUST OFFSHORE THE COAST OF THE CAROLINAS...THROUGH WED MORNING. TYPICAL MEDIUM RANGE TIMING AND AMPLITUDE DISTANCES BECOME MAGNIFIED DURING THIS TIME...WITH THE 00Z ECMWF REPRESENTING THE SOUTHERNMOST - AND CONSEQUENTLY RELATIVELY WETTEST FOR CENTRAL NC - SOLUTIONS FOR THE PERIOD MON-TUE. BASED ON A PREFERRED SLIGHTLY LESS AMPLIFIED/MORE NORTHWARD CONSENSUS OF MODEL CLUSTERING REPRESENTED WELL BY THE 00Z GFS...THE RELATIVE HIGHEST PROBABILITY OF PRECIPITATION (IN THE CHANCE RANGE) SHOULD BE CENTERED TOWARD THE NORTHEAST PIEDMONT WITH THE ARRIVAL OF THE LEAD SHEAR VORTICITY AND POSSIBLE INTERACTION WITH A LOW LEVEL MOIST AXIS OVER EASTERN NC THROUGH MON NIGHT. ANY PRECIPITATION THAT WERE TO FALL AFTER DARK MON...AFTER TEMPERATURES PEAK IN THE UPPER 40S TO LOWER 50S...WOULD BE IN THE FORM OF LIGHT SNOW OWING TO STRONG DEEP LAYER COOLING MON NIGHT - A CASE OF "THE COLD AIR CHASING THE MOISTURE". TRAILING SHEAR VORTICITY WILL CARVE THE TROUGH OFF THE COAST OF THE CAROLINAS TUE-TUE NIGHT. ASSOCIATED RE-STEEPENING OF THE LAPSE RATES ALOFT...AND LIFT/MOISTENING OF THE COLUMN...WILL RESULT IN YET ANOTHER SLIGHT TO CHANCE OF RAIN SHOWERS - OR SNOW SHOWERS WHERE/IF THE SUB-CLOUD LAYER FULLY WET-BULBS AND THEORETICALLY "MELTS OUT" A PROJECTED 1500-2000 FT ABOVE FREEZING BOUNDARY LAYER. THE REMAINDER OF THE LONG TERM WILL BE DRY AND CHILLY... PARTICULARLY WITH RESPECT TO LOWS BOTH WED AND THU MORNINGS...AS MODIFIED ARCTIC HIGH PRESSURE DRIFTS OVERHEAD IN THE WAKE OF THE TROUGH AXIS MOVING AWAY FROM THE NC COAST. && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... AS OF 215 PM FRIDAY... AVIATION CONDITIONS FURTHER DETERIORATE TO LIFR-IFR...THROUGH THE AFTERNOON AND EVENING. IN ADDITION...THE ARRIVAL OF AN EAST SOUTHEASTERLY TO SOUTHERLY LOW LEVEL JET AT 2000 FT...ATOP MUCH LIGHTER EASTERLY WINDS AT THE SURFACE...WILL PROMOTE A GOOD CHANCE OF LOW LEVEL WIND SHEAR CONDITIONS AT EASTERN TERMINALS THIS EVENING. PERIODS OF RAIN AND DRIZZLE...AND LIFR CONDITIONS...WILL CONTINUE OVERNIGHT...AS THE LOW PRESSURE SYSTEM TRACKS JUST INLAND OF THE COAST OF THE CAROLINAS. OUTLOOK: RAIN WILL LINGER THROUGH EARLY SATURDAY. WHILE CEILINGS AND VISIBILITIES GRADUALLY RISE THROUGH MVFR RANGE...TO VFR BY MID TO LATE MORNING IN THE NW... AND IN THE EAST BY EARLY AFTERNOON... AS THE LOW PRESSURE SYSTEM TRACKS UP THE MIDDLE ATLANTIC COAST AND AWAY FROM CENTRAL NC. VFR CONDITIONS ARE EXPECTED SUNDAY INTO MID NEXT WEEK AS MOST WEATHER MAKERS SHOULD REMAIN JUST TO OUR NORTH. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT SHORT TERM...BADGETT LONG TERM...MWS AVIATION...BADGETT

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