Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 150237 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 937 PM EST SUN DEC 14 2014 .SYNOPSIS... A BROAD AREA OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE WEST TONIGHT AND THEN MOVE OFFSHORE LATE IN THE DAY ON MONDAY. BY TUESDAY, THIS HIGH PRESSURE SYSTEM WILL GIVE WAY TO A WARM FRONTAL BOUNDARY COMING UP FROM THE SOUTHWEST. A COLD FRONTAL BOUNDARY WILL THEN MOVE THROUGH THE REGION ON WEDNESDAY. ANOTHER AREA OF HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE LATTER HALF OF THE WEEK. LOW PRESSURE WILL THEN TRACK FROM THE SOUTH UP THE EAST COAST BY THE START OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... THE CLOUD COVER REMAINS OVER MUCH OF THE AREA THIS EVENING AS MOISTURE REMAINS TRAPPED BENEATH THE INVERSION. THERE IS AN AREA OF SOME CLEARING ACROSS OUR EASTERN ZONES BUT IT IS HITTING A WALL AS IT TRIES TO MOVE FURTHER INLAND. THE GUIDANCE DOES INDICATE THAT THERE WILL BE A PERIOD OVERNIGHT WHERE WE ARE ABLE TO BREAK OUT FROM THE CLOUDS AND SEE SOME CLEARING, BE IT PARTLY CLOUDY OR MOSTLY CLEAR. BUMPED UP THE OVERNIGHT LOWS A FEW DEGREES AS THE TREND THE PAST FEW NIGHTS HAS BEEN FOR SOME SLIGHTLY WARMER THAN FORECAST TEMPERATURES, EVEN IN THOSE AREAS WHERE WE HAVE SEEN THE CLOUDS ERODE. LOWS WILL BE IN THE LOWER TO 30S MOST SPOTS AND SOME 20S ACROSS THE HIGHER TERRAIN. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... MUCH OF THE GUIDANCE INDICATES THAT MONDAY WILL HAVE MORE SUN THAN CLOUDS. THE UPPER RIDGE AXIS WILL CROSS THE REGION DURING THE AFTERNOON. THERE WILL BE SOME INCREASE IN HIGH CLOUDS LATER IN THE DAY AS A WAA PATTERN BEGINS TO DEVELOP AHEAD OF THE NEXT SYSTEM. HIGHS WILL RISE INTO THE MID/UPPER 40S SOUTH/EAST AND LOW TO MID 40S NORTH/WEST. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... MONDAY NIGHT: DRY WITH HIGH PRESSURE IN PLACE. WINDS GRADUALLY SHIFTING TO THE SOUTH AS A HIGH PRESSURE SYSTEM MOVES THROUGH THE REGION. NOT MUCH DEVIATION FROM MOS GUIDANCE GIVEN A QUIET PERIOD. TUESDAY THROUGH WEDNESDAY: THIS CONTINUES TO BE THE PERIOD OF FOCUS FOR FRONTAL PASSAGES. SOME RAIN SHOWERS WITH LIGHT QPF ARE LIKELY TO OCCUR WITH THE WARM FRONT TUESDAY AFTERNOON AND EVENING, SLOWER WHEN COMPARED TO YESTERDAY`S MODEL RUNS. EVEN WITH SOUTHERLY FLOW TUESDAY, CLOUDS AND PRECIPITATION MAY KEEP HIGH TEMPERATURES IN THE 40`S. HOWEVER, WITH THE SLOWER FRONTAL TIMING, WAS ABLE TO GO WARMER THAN MOS OR MODELED TWO METER TEMPERATURES ACROSS EASTERN PARTS OF THE CWA WHICH HAS THE BEST CHANCE OF HIGHS OVER 50. THE SLOWER FRONTAL TIMING ALLOWS FOR ENOUGH WARMING FOR AN ALL RAIN FORECAST. QPF WILL BE FAIRLY LIGHT UNDER 1/4 INCH USING THE SREF AND PC GUIDANCE. THE MAIN PUSH OF COLD AIR BEHIND THE LOW PRESSURE MAY NOT COME UNTIL LATE WEDNESDAY AFTER THE PASSAGE OF A COLD FRONT. WEDNESDAY MAY END UP THE WARMEST DAY OF THE WEEK AS WE AWAIT THE COLD FRONT AND SEE MORE IN THE WAY OF SUN. WENT A COUPLE OF DEGREES ABOVE MODELED TWO METER TEMPERATURES AND MOS GUIDANCE. SOME AFTERNOON CUMULUS AND VERY LIGHT RAIN/SNOW SHOWERS MAY OCCUR NW WITH THE AID OF ELEVATION WEDNESDAY AFTERNOON, ONLY SLIGHT CHANCE FOR PRECIP ATTM. WEDNESDAY NIGHT THROUGH FRIDAY NIGHT: ANOTHER HIGH PRESSURE SYSTEM BUILDS IN WITH A COOLER AIRMASS. PERHAPS SOME BUILDUP OF AFTERNOON CUMULUS AND PATCHY SNOW FLURRIES DUE TO STEEP LAPSE RATES ACROSS THE HIGHER ELEVATIONS WITH THE BEST CHANCE ON THURSDAY. WENT CLOSER TO MODELED TWO METER TEMPERATURES GIVEN THE NORTHWESTERLY FLOW. SATURDAY THROUGH SUNDAY: THIS PERIOD HAS THE MOST UNCERTAINTY. LOW PRESSURE HAS BEEN CONSISTENTLY MODELED TO FORM TO OUR SOUTH AND MOVE NORTHEAST. HIGH PRESSURE BUILDING IN TO OUR NORTH COUPLED WITH A LOW TO OUR NORTHEAST MAY LIMIT THE ABILITY OF HEIGHTS TO REBOUND NORTH IN THIS PERIOD AND ALLOW FOR COLDER AIR TO LINGER. AS A RESULT, THIS LOW COULD HAVE A MORE FAVORABLE TRACK SOUTH AND EAST OF US FOR WINTRY PRECIPITATION ACROSS THE REGION. A MORE INLAND TRACK WOULD LEAD TO A WARMER SOLUTION. THE LAST FEW ECMWF RUNS ARE MORE INTENSE IN TERMS OF LOWER PRESSURE, TRACKING A LOW FROM ALABAMA NORTHEAST UP THE COAST. THE CMC MODEL IS QUITE A BIT MORE SUPPRESSED AND SHEARS THE SYSTEM INTO PIECES KEEPING A WEAK SHORTWAVE ALONG THE GULF COAST, DISCOUNTING THIS. WE ALSO HAVE THE 12Z GFS WHICH HAS A LOW TRACKING TO BUFFALO BEFORE FORMING AN AWKWARD SECONDARY LOW TO THE SOUTHEAST. APPARENT MODEL BIASES APPEAR TO BE AT WORK WITH THE GFS AS IT FORMS THE LOW VERY FAR NORTH OVER TEXAS. A HIGHER RESOLUTION GFS IS MORE IN LINE WITH THE UKMET. THE UKMET HAS A SIMILAR TRACK TO THE ECMWF TILL SATURDAY MORNING BUT IS MUCH WEAKER. FOR NOW OUR FORECAST WILL REFLECT 1/2 00Z ECMWF ENSEMBLE MEAN, 1/4 HIRES GFS AND 1/4 UKMET. THIS PLACES NO EMPHASIS ON THE HIGHLY INTENSE ECMWF OR THE HIGHLY SUSPECT 12Z GFS SOLUTION. WITH THIS IN MIND, CURRENT THINKING IS THAT LOW PRESSURE TRACKS FROM THE GULF COAST TO EASTERN TENNESSEE SATURDAY MORNING. THEN A COASTAL LOW OFF VIRGINA BEACH DEVELOPS WHICH THEN SLIDES EAST/NORTHEAST OF OUR REGION ON SUNDAY. THIS TRACK ALLOWS FOR BOTH CHANCES OF RAIN AND SNOW FROM ROUGHLY THE FALL LINE AND POINTS TO THE SOUTHEAST WITH COASTAL SECTIONS MOST LIKELY TO CHANGE TO ALL RAIN FOR A TIME. INTERIOR AREAS SUCH AS THE LEHIGH VALLEY AND POCONOS HAVE THE BEST CHANCE STAYING ALL SNOW. THE POTENTIAL EXISTS FOR ACCUMULATING SNOW WHICH COULD IMPACT HOLIDAY TRAVEL. RAISED POPS TO HIGH CHANCE CENTERED ON SATURDAY NIGHT. DETAILS ARE SILL UNCERTAIN IN THE EXACT TRACK AND EVOLUTION OF THIS STORM, PLEASE STAY TUNED TO TO FUTURE FORECAST UPDATES. && .AVIATION /03Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. PERSISTENT STRATOCU CONTINUES TO KEEP MVFR CONDITIONS ACROSS THE REGION. THERE ARE SOME BREAKS BUT THE HEIGHT OF THE CLOUD BASES HAS REMAINED AROUND 3300FT OR LOWER FOR THE BETTER PART OF THE DAY AND WILL CONTINUE THROUGH THIS EVENING AND INTO THE OVERNIGHT. THE CLOUDS WILL START TO LIFT AND THEN THIN OUT OVERNIGHT AND WE SHOULD SEE SOME CLEARING FOR ALL TERMINALS WITH A PERIOD OF VFR CONDITIONS EXPECTED, A SHORTER PERIOD OF VFR ACROSS THE NORTH WITH A LONGER PERIOD OF VFR ACROSS THE SOUTH. CLOUDS LOOK TO FILL BACK IN AGAIN TOWARD MONDAY AFTERNOON. THE GUSTY NORTHWEST WINDS WILL START TO SUBSIDE AS WE HEAD INTO THE OVERNIGHT HOURS AND THEN REMAIN FAIRLY LIGHT THROUGH MONDAY. OUTLOOK... MONDAY NIGHT THROUGH TUESDAY MORNING : VFR WITH INCREASING CLOUDS BY TUESDAY MORNING. TUESDAY AFTERNOON THROUGH WEDNESDAY: MVFR CEILINGS AT TIMES WITH SCATTERED SHOWERS, OTHERWISE VFR. CLEARING BY LATE WEDNESDAY. WINDS GENERALLY UNDER 10 KNOTS SHIFTING FROM SOUTH TO NORTHWEST LATE WEDNESDAY. ISOLATED WIND GUSTS TO 20 KNOTS WEDNESDAY AFTERNOON. WEDNESDAY NIGHT THROUGH FRIDAY NIGHT: VFR. SCATTERED NORTHWEST WIND GUSTS UP TO 20 KNOTS EACH AFTERNOON.
-- End Changed Discussion --
&& .MARINE... NO MARINE FLAGS WILL BE NEEDED TONIGHT OR MONDAY. WINDS HAVE BEEN NORTHWEST ON THE WATERS TODAY WITH SPEEDS MOSTLY AROUND 10 TO 15 KNOTS. A PERIOD OF GUSTY WINDS (UP TO 20 KNOTS) IS POSSIBLE EARLY THIS EVENING...BUT THEN WINDS WILL SETTLE BACK AROUND 10 KNOTS AGAIN OVERNIGHT. SEAS ON THE OCEAN 2 TO 4 FT FOR THE MOST PART. FAIR WEATHER EXPECTED TONIGHT AND MONDAY. OUTLOOK... MONDAY NIGHT THROUGH TUESDAY: SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA ATTM. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT: SCA WINDS AND SEAS POSSIBLE DUE TO COLD FRONT PASSAGE WITH WIND SHIFT FROM SOUTHWEST TO NORTHWEST. HIGHEST CHANCE WITH GUSTS WEDNESDAY NIGHT OF MEETING SCA CRITERIA. THURSDAY THROUGH FRIDAY NIGHT: SEAS LIKELY TO BE BELOW SCA CRITERIA. SOME NORTHWEST WIND GUSTS NEAR 25 KNOTS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GAINES NEAR TERM...MEOLA SHORT TERM...O`HARA LONG TERM...GAINES AVIATION...GAINES/MEOLA MARINE...GAINES/O`HARA

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