Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 201917 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 217 PM EST SAT DEC 20 2014 .SYNOPSIS... WEAK LOW PRESSURE WILL TRACK FROM THE GULF OF MEXICO EASTWARD AND OFF THE SOUTHEAST COAST THROUGH TONIGHT. HIGH PRESSURE WILL BE OVER THE AREA AGAIN DURING SUNDAY. ANOTHER LOW PRESSURE AREA MOVES NORTHEAST OUT OF THE GULF OF MEXICO AND UP ALONG THE CAROLINA COAST LATE SUNDAY NIGHT THROUGH MONDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... LATEST ANALYSIS SHOWS ~1028 MB SFC HIGH PRESSURE CENTERED OVER EASTERN VA...WITH WEAK (~1018 MB) SFC LOW PRESSURE OVER SOUTHERN GA/NORTH FL. ISENTROPIC LIFT PER 12Z NAM AT 285K SFC SEEMS TO HAVE A DECENT HANDLE ON THE OVERRUNNING PRECIP FOCUSING OVER CENTRAL AND EASTERN NC AND INTO FAR SOUTHERN VA. A FEW REPORTS OF -SN WITH VSBYS 1-3 SM OVER CENTRAL NC. NAM/RAP DEPICTION OF SFC WET BULB TEMPERATURES OF 32-33 F LINES UP FAIRLY WELL WITH RAIN/SNOW LINE. HAVE ADDED FLURRIES TO PORTIONS OF CENTRAL VA ALONG/WEST OF I-95 THROUGH NOON...WITH 20-30% POPS FOR RAIN/SNOW DOWN NEAR THE VA/NC BORDER AND FOR INTERIOR NE NC. PRECIP IS VERY LIGHT SO NO ACCUMULATION EXPECTED ANYWHERE. FORCING/LIFT WEAKENS AND FOCUSES OVER SE NC AFTER 18Z...SO WILL LIMIT POPS AFTER 18Z TO NE NC AND FAR SE VA FOR JUST A LOW CHC (20-30%) OF LIGHT RAIN. CLOUDY TO MOSTLY CLOUDY TODAY WITH HIGHS IN THE UPPER 30S NW TO MID 40S SE. SFC HIGH PRESSURE REBOUNDS TONIGHT WITH DECREASING CLOUDS. LOWS IN THE MID 20S NORTH TO THE LOW 30S SOUTH. && .SHORT TERM /SUNDAY THROUGH MONDAY/... HIGH PRESSURE REMAINS ENTRENCHED OVER THE MID-ATLANTIC SUNDAY WITH A MIX OF SUN AND CLOUDS. SEASONABLE HIGHS OF 45-50. NEXT SYSTEM...THIS ONE MORE AMPLIFIED WILL AFFECT THE AREA ON MON...WITH LIKELY TO CATEGORICAL POPS ALL ZONES MON AM/MON AFTN. LOOKS LIKE ALL RAIN ASIDE FROM A BRIEF MIX POSSIBLE AT ONSET IN FAR NW COUNTIES. AT THIS POINT...IT DOES NOT APPEAR ENOUGH FROZEN PCPN WOULD OCCUR TO CAUSE ANY CONCERNS. LOWS SUNDAY NIGHT FROM AROUND 30 NW TO AROUND 40 VA BEACH. HIGHS MON ONLY AROUND 40 NW TO THE MID 50S FAR SE IN CAD SETUP. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... LOW PRESSURE LIFTS TO THE NE MONDAY NIGHT WITH POPS SLOWLY DIMINISHING FROM SW-NE OVERNIGHT. MID-LEVEL RIDGING BRIEFLY BUILDS INTO THE REGION TUESDAY. HOWEVER...MOIST SOUTHERLY FLOW ORIGINATING FROM THE GULF STREAM WILL PREVAIL SO LOW CHC (30%) POPS WILL BE MAINTAINED. A VERY DYNAMIC SYSTEM LIFTS NNE WEST OF THE APPALACHIANS TUESDAY NIGHT WITH THE ATTENDANT COLD FRONT CROSSING THE MID-ATLANTIC WEDNESDAY. THE FIRST POTENTIAL OF RAIN ARRIVES TUESDAY NIGHT ASSOCIATED WITH MOIST WAA. THE SECOND POTENTIAL WILL BE WEDNESDAY AHEAD OF THE COLD FRONT. THERE IS A POTENTIAL FOR THUNDER WEDNESDAY AS SURFACE DEWPOINTS POTENTIALLY EXCEED 60F (ESPECIALLY OVER THE COASTAL PLAIN). THE PATTERN DOES SUPPORT THE POSSIBILITY OF A DYNAMICALLY FORCED LINE OF CONVECTION CONTAINING STRONG WIND GUSTS AS CURRENT FORECAST GUIDANCE SUGGESTS A 925-700MB WIND FIELD AVERAGING 40-50KT. THIS WOULD BE A CLIMATOLOGICALLY RARITY THIS TIME OF YEAR...SO CONFIDENCE IS ON THE LOW-SIDE GIVEN THAT THIS IS 5-6 DAYS OUT. TEMPERATURES WILL BE VERY MILD AHEAD OF THE FRONT TUESDAY AND WEDNESDAY...WITH HIGHS AVERAGING FROM THE MID 50S NW...TO MID/UPPER 60S SE. DRY AND BREEZY CONDITIONS WILL LIKELY PREVAIL BY CHRISTMAS DAY...WITH HIGH TEMPERATURES OF 50-55. THE FLOW BECOMES MORE SW BY FRIDAY WITH CURRENT FORECAST HIGHS OF 55-60...BUT 60-65 IS POSSIBLE BASED ON LOW-LEVEL THICKNESS FIELDS. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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MOSTLY VFR CONDITIONS EXPECTED ACROSS THE AREA WITH SOME -RA OR SPRINKLES DEPICTED ON RADAR ACROSS NE NC. HIGH PRESSURE MOVES WEST OVERNIGHT AS THE WEAK WAVE OFF THE SE US COAST CONTINUES TO PUSH OUT TO SEA. LIGHT WINDS AND VFR CONDITIONS EXPECTED THROUGH SUN EVENING BEFORE THE APPROACH OF THE NEXT WAVE MOVING NE FROM THE GULF OF MEXICO AND UP THE EAST COAST. OUTLOOK...A SERIES OF LOW PRESSURE SYSTEMS AND COMPLEX FRONTAL BOUNDARIES WILL BRING CHANCES FOR RAIN AND PERIODS OF LOW CEILINGS AND VISIBILITIES MONDAY THROUGH WEDNESDAY.
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&& .MARINE... LATEST OBS HIGH PRESSURE SPREADS EAST ACROSS NEW ENGLAND THROUGH TONIGHT, RIDGING SOUTH INTO THE AREA TODAY. MEANWHILE, WEAK SFC LOW PRESSURE WILL PASS SOUTH OF THE REGION LATER TODAY AND TONIGHT. THIS WILL MAINTAIN LIGHT NORTHERLY FLOW ~10 KT OVER THE MARINE AREA TODAY. HIGH PRESSURE MOVES FARTHER E SUNDAY AND SUNDAY NIGHT, AS LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST SUNDAY NIGHT BEFORE TRACKING NE OFF THE LOWER MID ATLANTIC COAST LATER MONDAY AND MONDAY NIGHT. THE RESULTANT TIGHTENING SURFACE PRESSURE GRADIENT WILL ALLOW ONSHORE (EAST) FLOW TO GRADUALLY INCREASE MONDAY AFTN, GRADUALLY BUILDING SEAS MONDAY NIGHT AND EARLY TUESDAY. 15-20KT EASTERLY FLOW OVER THE OCEAN AND LOWER BAY COULD PRODUCE A PERIOD OF SCA CONDITIONS ESPECIALLY OVER THE SRN OCEAN ZONES (MAINLY FOR SEAS) AND LOWER BAY/MOUTH OF JAMES. THERE IS NO CAA IN THE WAKE OF THIS LOW...SO SUB-SCA CONDITIONS SHOULD PREVAIL BEHIND THE SYSTEM LATER MONDAY NIGHT INTO TUESDAY. A STRONG LOW PRESSURE SYSTEM LOOKS TO DEVELOP ACROSS THE OHIO VALLEY, TRACKING WEST OF THE MOUNTAINS TUESDAY NIGHT. HOWEVER, THIS SYSTEM WILL PUSH A STRONG COLD FRONT ACROSS THE MID ATLANTIC COAST LATER WEDNESDAY. SCA CONDITIONS ARE LIKELY WEDNESDAY NIGHT INTO CHRISTMAS DAY AS HIGH PRESSURE BUILDS IN FROM THE WNW. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM/LKB SHORT TERM...JDM/LKB LONG TERM...AJZ/MAS AVIATION...MAM/DAP MARINE...MAM

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