Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 180744 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 344 AM EDT SAT OCT 18 2014 .SYNOPSIS....A DRY COLD FRONT WILL CROSS THE CAROLINAS AND VA THIS MORNING. A SECONDARY COLD FRONT ATTENDANT TO A POTENT BUT MOISTURE- STARVED SHORTWAVE TROUGH ALOFT WILL CROSS THE REGION THIS EVENING. HIGH PRESSURE WILL FOLLOW AND BUILD INTO THE REGION FROM THE NORTHWEST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 320 AM SATURDAY... TODAY: A LEAD SHORTWAVE TROUGH OVER THE EASTERN GREAT LAKES THIS MORNING WILL PIVOT ENE AND PROPEL A SURFACE COLD...WHICH AT 07Z WAS NEAR THE WEST SLOPES OF THE APPALACHIANS...SOUTHEAST AND ACROSS CENTRAL NC THROUGH DURING THE LATE MORNING AND MIDDAY HOURS. A LACK OF BOTH MOISTURE AND INSTABILITY EAST OF THE APPALACHIANS WILL YIELD DRY CONDITIONS FOR CENTRAL NC. DESPITE CAA BEHIND THE FRONT...NW FLOW AT H85 (PER REGIONAL VWP DATA) THAT HAS ALREADY VEERED FROM WESTERLY AT THE TIME OF THE 00Z RAOBS...WILL PROMOTE DOWNSLOPE WARMING THAT SHOULD OFFSET THE CAA...AND ALSO PRODUCE A 10-15 MPH NW SURFACE WIND THAT WILL GUST INTO THE UPPER TEENS TO LOWER 20S MPH. STATISTICAL GUIDANCE TYPICALLY VERIFIES WITH LESS ERROR THAN OTHER MAX TEMPERATURE FORECASTING TECHNIQUES IN SUCH A PATTERN...SO THE VERY SIMILAR MET/MAV MOS WILL BE FOLLOWED - AROUND 70 NW PIEDMONT TO UPPER 70S SANDHILLS AND SOUTHERN COASTAL PLAIN. TONIGHT: A SECONDARY COLD FRONT...ONE ACCOMPANYING A POTENT SHORTWAVE TROUGH FORECAST TO AMPLIFY FROM NW WISCONSIN THIS MORNING TO NC/VA BY 06Z...WILL SWEEP SOUTHEAST ACROSS CENTRAL NC THIS EVENING. THIS FRONT WILL ALSO BE A MOISTURE-STARVED ONE...WITH SIMPLY A PERIOD OF PARTLY CLOUDY CONDITIONS...TO PERHAPS BRIEFLY MOSTLY CLOUDY ONES MAINLY NEAR THE VA BORDER...AS THE MID LEVEL TROUGH AND ASSOCIATED (RELATIVE) MOIST AXIS PIVOTS EAST. CAA-DRIVEN LOWS IN THE 40S. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 340 AM SATURDAY... BENEATH STRONG HEIGHT RISES ALOFT AND ASSOCIATED SUBSIDENCE...1020- 1025 MB SURFACE HIGH PRESSURE WILL BUILD EAST ACROSS THE TN VALLEY AND CENTRAL APPALACHIANS...TO A POSITION DIRECTLY OVER EAST-CENTRAL NC BY 12Z MON. DESPITE ABUNDANT SUNSHINE...TEMPERATURES WILL BE NOTICEABLY COOLER...WITH HIGHS GENERALLY IN THE LOWER TO MIDDLE 60S GIVEN PROJECTED 00Z LOW LEVEL THICKNESSES AROUND 1350 METERS. SIMILAR THICKNESS VALUES AT 12Z MON WOULD SUPPORT WIDESPREAD 30S - INCLUDING LOWER TO MIDDLE ONES IN THE TYPICALLY COOLER RURAL AREAS - IF IDEAL RADIATION COOLING CONDITIONS WERE REALIZED. WHILE CALM WILL PREVAIL UNDER THE INFLUENCE OF THE SURFACE RIDGE...THE APPROACH OF A DEAMPLIFYING UPPER WAVE THAT WAS LOCATED OVER SW NEW MEXICO THIS MORNING WILL RESULT IN INCREASING CIRRUS FROM THE WEST OVERNIGHT. GIVEN THE EXPECTED INCREASING HIGH CLOUDS...EXPECT LOWS MOSTLY BETWEEN 35 AND 40 DEGREES - COOLEST EAST AND NORTHEAST WHERE CLOUDS WILL BE SLOWEST TO ARRIVE/WELL AFTER MIDNIGHT. PATCHY FROST WILL BE POSSIBLE IN THE AFOREMENTIONED TYPICALLY COOLER AREAS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 340 AM SATURDAY... HIGH PRESSURE OVER THE REGION MONDAY MORNING WILL PUSH OFFSHORE DURING THE DAY AND ALLOW SOME ADDITIONAL MODERATION OF TEMPS MONDAY AND TUESDAY BEFORE A SHORTWAVE DIVES THROUGH THE MIDWEST AND CROSSES CENTRAL NC TUESDAY EVENING. DESPITE THE RETURN FLOW AHEAD OF THE SHORTWAVE AND WARMING INTO THE UPPER 60S AND LOWER 70S...MOISTURE WILL BE VERY LIMITED...CONFINED TO A SHALLOW LAYER AROUND 700MB. MAY SEE A FEW SHOWERS WITH THE FRONT TUESDAY EVENING...ESPECIALLY NEAR THE VA BORDER WHERE HEIGHT FALLS AND DCVA ASSOCIATED WITH THE TROUGH ALOFT WILL SLIGHTLY STRONGER. WILL MAINTAIN THE SLIGHT CHANCE FOR A FEW LIGHT SHOWERS TUESDAY AFTERNOON/EVENING. BEHIND THE FRONT...THE UPPER TROUGH IS FORECAST TO CONTINUE DEEPENING AND EVENTUALLY CLOSE OFF NEAR THE MID-ATLANTIC COAST. THE GFS AND ECMWF BOTH SUGGEST THE POTENTIAL FOR SOME ADDITIONAL SHOWERS AS THE CORE OF THE COLDER AIR ALOFT MOVES OVERHEAD WEDNESDAY...THOUGH CONFIDENCE IN THIS IS PRETTY LOW GIVE THE LACK OF MOISTURE IN FORECAST SOUNDING`S. OTHERWISE...THE PATTERN SHOULD BE DRY FOR THE REMAINDER OF THE REMAINDER OF THE WEEK AS THE UPPER LOW SLOWLY BEGINS TO DRIFT OFFSHORE. THICKNESSES ARE PROGGED TO FALL BACK INTO THE 1340-1345M RANGE...WHICH IS ABOUT 10-15M BELOW NORMAL AND SUGGEST TEMPS IN THE LOW/MID 60S MIDWEEK AND THEN REBOUNDING BACK TOWARD THE LOWER 70S. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 215 AM SATURDAY... A PAIR OF DRY COLD FRONTS WILL CROSS CENTRAL NC...ONE THIS MORNING AND ANOTHER THIS EVENING. INITIALLY LIGHT SW SURFACE WINDS WILL VEER TO WNW AND INCREASE INTO THE 8-14 KT RANGE WITH GUSTS OF 15-20 KTS...AS THE LEAD COLD FRONT CROSSES THE AREA BETWEEN 14-17Z. A PERIOD OF BROKEN 3000-3500 FT CLOUDINESS MAY SPILL EAST OF THE APPALACHIANS/INTO THE NW NC PIEDMONT (KINT/KGSO) THIS EVENING...WITH FEW TO SCATTERED CLOUD BASES BETWEEN 3500-5000 FT ELSEWHERE AND OTHERWISE. WHILE SURFACE WINDS WILL LESSEN AROUND SUNSET...THE PASSAGE OF THE SECONDARY COLD FRONT WILL LIKELY CAUSE THEM TO PICK UP ONCE AGAIN...INTO THE 7-12 KT RANGE WITH A FEW GUSTS MAINLY AT TRIAD TERMINALS...BETWEEN 00-06Z. OUTLOOK: THE DEVELOPMENT OF AN UPPER LOW OVER THE MIDDLE ATLANTIC STATES WILL RESULT IN A CHANCE OF SHOWERS TUE-WED. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...BLS AVIATION...MWS

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