Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 190513 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 115 AM EDT TUE AUG 19 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL CROSS THE REGION THROUGH MID-WEEK IN ASSOCIATION WITH A NORTHWEST FLOW ALOFT. && .NEAR TERM /THROUGH THE OVERNIGHT/... AS OF 1010 PM MONDAY... A RATHER POTENT S/W (FOR MID-AUGUST) CROSSING VA/NORTHERN NC INTERACTING WITH A MODERATELY UNSTABLE AIR MASS HELPED TO INITIATE AND SUSTAIN SCATTERED STRONG/LOCALLY SEVERE STORMS LATE THIS AFTERNOON TROUGH EARLY EVENING. A FEW STORMS EXHIBITED RATHER DEEP AND DECENT ROTATION...ESPECIALLY THOSE ALIGNED ALONG A WEAK SFC BOUNDARY STRETCHING WEST-TO-EAST ACROSS FAR NORTHERN NC. THIS BOUNDARY WAS LIKELY THE OLD OUTFLOW FROM AN COMPLEX OF SHOWERS/STORMS THAT MOVED OVER THE VA BORDER COUNTIES EARLIER THIS MORNING. OVERALL STORM ORGANIZATION WAS MOSTLY MULTI-CELLULAR WITH A FEW CELLS EXHIBITING SUPERCELLULAR CHARACTERISTICS (GRANVILLE/VANCE, AND NASH/WILSON/EDGECOMBE COME TO MIND). BULK SHEAR AT STORM INITIATION WAS CLOSE TO 30-35KTS ACROSS THE FAR N-NE. IF SHEAR HAD BEEN A LITTLE STRONGER...A FEW TORNADOES MAY HAVE DEVELOPED. INSTEAD...RECEIVED A FEW REPORTS OF MARGINALLY SEVERE HAIL WITH JUST ISOLATED REPORTS OF WIND DAMAGE. S/W RESPONSIBLE FOR THIS ROUND OF CONVECTION WILL CONTINUE TO LIFT E- NE AWAY FROM OUR REGION OVERNIGHT AND STABLE LOW LEVEL AIR MASS AND WEAK SUBSIDENCE IN THE WAKE FO THE S/W SHOULD RESULT IN LITTLE IF ANY SHOWER ACTIVITY OVERNIGHT. THE STABLE LOW LEVEL AIR MASS COUPLED WITH A LIGHT WIND REGIME AT THE SURFACE AND ABUNDANT MOISTURE SHOULD CAUSE AREAS OF LOW CLOUDS/FOG TO DEVELOP LATE TONIGHT...PERSISTING INTO TUESDAY MORNING. MIN TEMPS NEAR 70-LOWER 70S. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 1019 PM MONDAY... THE NEXT S/W...CURRENTLY OVER THE WESTERN TN VALLEY...IS PROJECTED TO AFFECT CENTRAL NC TUESDAY AFTERNOON-TUESDAY EVENING. ONCE AGAIN THE ATMOSPHERE WILL CONTAIN ENOUGH MOISTURE AND INSTABILITY TO TRIGGER SCATTERED CONVECTION. THE ONE DIFFERENCE HOWEVER WILL BE THE LACK OF SUFFICIENT SHEAR TO ORGANIZE STORMS. CURRENTLY APPEARS THAT BULK SHEAR WILL TOP OUT AT 20-25 KTS. THUS COULD SEE STORMS TRY TO ORGANIZE INTO BROKEN BOW SEGMENTS WITH AN ISOLATED SEVERE STORM POSSIBLE. HOWEVER...APPEARS THAT BULK OF STORMS WILL REMAIN BELOW SEVERE THRESHOLDS. ALSO...IF THE LOW CLOUDS PERSISTS PAST MID DAY...THIS WILL LIMIT INSOLATION WITH RESULTING LOW LEVEL INSTABILITY MARGINAL AT BEST. CURRENTLY EXPECT COVERAGE TO BE NO WORSE THAN THIS AFTERNOON...ANYTHING..IT MAY BE LESS ACROSS THE NORTHERN HALF BUT A LITTLE MORE ROBUST ACROSS THE SOUTH. MAX TEMPS UPPER 80S TO LOWER 90S WILL BE ACHIEVED IF LOW CLOUDS DISSIPATE EARLY ENOUGH TUESDAY MORNING. IF LOW CLOUDS LINGER UNTIL MID DAY....MAX TEMPS MAY END UP BEING 3-5 DEGREES...COOLER ESPECIALLY ACROSS THE NORTH. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 220 PM MONDAY... THE MAJOR PROBLEM THROUGH THE LONG TERM PERIOD WILL BE DISCERNING WHEN AND WHERE A HIGHER PROBABILITY OF PRECIPITATION WILL OCCUR. THERE IS GOOD MODEL CONSENSUS AS TO THE TRANSITION TO A LARGER SCALE BLOCKING PATTERN OVER THE EASTERN CONUS THROUGH THE WEEKEND. THE GRADUAL MIGRATION OF AN UPPER LOW ACROSS THE GREAT LAKES AND OFF THE MID ATLANTIC COAST WEDNESDAY THROUGH FRIDAY WILL AMPLIFY INTO A DEEPER UPPER TROF DOWN THE COAST INTO EARLY NEXT WEEK. CONCURRENT AMPLIFICATION OF AN UPPER RIDGE WEST OF THE AREA WILL PRODUCE PERSISTENT NORTHWEST FLOW WHICH WILL PRESENT THE USUAL PROBLEMS WITH TIMING FEATURES THAT WILL BE STEERED INTO THE AREA. AIRMASS WILL BE REASONABLY WARM (UPPER 80S TO LOW 90S) AND MOIST...PW ~1.5 INCHES... BUT MOISTURE ADVECTION WILL BE HAMPERED BY WESTERLY FLOW ACROSS THE DEEP SOUTH...SO CHANCES OF RAIN WILL BE IN THE CLIMATOLOGICAL RANGE...30 PERCENT-ISH...WEDNESDAY THROUGH FRIDAY. A COOL SURGE WILL PROGRESS SOUTH AND ACROSS THE AREA FRIDAY NIGHT AS HIGH PRESSURE OVER FAR EASTERN CANADA IS SHUNTED DOWN THE EASTERN SLOPES OF APPALACHIANS. THIS WILL ENHANCE A COASTAL TROF IN PLACE OFFSHORE AND RESULT IN DEEP NORTH TO NORTHEAST FLOW WITH ACCOMPANYING MOIST AND COOLER MARINE-FLAVORED AIRMASS PERSISTING THROUGH MONDAY. ISENTROPIC LIFT WILL BE MINIMAL...AND MID LEVEL FEATURES IN THE NORTHWEST FLOW WILL BE NIL-CONFIDENCE THIS FAR IN ADVANCE. WOULD EXPECT PATCHY LIGHT RAIN/SHOWERS TO BE THE PREDOMINANT TYPE OF PRECIP...WITH POTENTIAL FOR CONVECTION HINGING ON UPSTREAM FEATURES WE MIGHT SEE 24-48 HOURS IN ADVANCE. THICKNESSES WOULD INDICATE A 3-5 DEGREE COOL DOWN FOR SATURDAY...AND ANOTHER 1-2 DEGREES SUNDAY AND MONDAY. THIS WOULD KEEP US IN THE MID TO UPPER 80S EACH DAY...WHICH IS MORE LIKELY TO ERR ON THE HIGH SIDE GIVEN THE LOOK OF THE PATTERN AND POTENTIAL FOR SOCKING IN SOME SATURATED MARINE LAYER AIR OVERNIGHT WITH ACCOMPANYING DENSE FOG/LOW STRATUS TO START THE DAYS. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 115 AM TUESDAY... 24-HR TAF PERIOD: MODERATE TO HEAVY RAINFALL FROM STORMS THAT ROLLED THROUGH THE AREA EARLIER THIS EVENING WILL SET THE STAGE FOR AREAS OF FOG AND STRATUS OVERNIGHT...ESPECIALLY AT THE NORTHERN TAF SITES (KINT/KGSO/KRDU/KRWI)...WHERE THE HEAVIEST RAIN FELL. EXPECT VFR CONDITIONS SHOULD GENERALLY RETURN BY MID MORNING AT THE LATEST. ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON AS ANOTHER UPPER LEVEL DISTURBANCES TRACKS THROUGH THE AREA. THE HIGHEST PROBABILITY OF SHOWERS AND STORMS WILL BE ACROSS SOUTHERN PORTIONS OF CENTRAL NC. THUS... HAVE ONLY PLACED A PROB30 GROUP AT KFAY FOR TUESDAY AFTERNOON. LOOKING AHEAD: EXPECT A CLIMATOLOGICAL POTENTIAL FOR AFT/EVE SHOWERS AND STORMS THROUGH MID TO LATE WEEK...ALONG WITH A POTENTIAL FOR FOG AND/OR LOW CEILINGS DURING THE EARLY MORNING HOURS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...WSS SHORT TERM...WSS LONG TERM...MLM AVIATION...BSD/VINCENT

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