FXUS61 KPHI 110838
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
338 AM EST SAT FEB 11 2012
.SYNOPSIS...
A BROAD AREA OF LOW PRESSURE ALONG THE SOUTHERN MID ATLANTIC COAST
EARLY THIS MORNING WILL CONSOLIDATE AND DEEPEN AS IT MOVES NORTHEAST
AND OUT TO SEA TODAY, AND A COLD FRONT WILL CROSS OUR AREA THIS
AFTERNOON. THERE WILL BE A STRONG NORTHWEST FLOW AND SOME COLDER AIR
IN THE WAKE OF THE FRONT. A SECONDARY COLD FRONT WILL CROSS THE AREA
LATE SUNDAY. HIGH PRESSURE WILL BUILD IN ON MONDAY, THEN TWO WEAK
SYSTEMS COULD AFFECT THE REGION DURING THE MIDDLE TO LATTER PART OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WE WILL KEEP THE WINTER WEATHER ADVISORY FOR THE MORNING. THE
RAIN/SNOW LINE HAS ADVANCED ACROSS THE NJ/NRN DELMARVA AREA EARLY
THIS MORNING AND A LIGHT ACCUMULATING SNOW IS IN PROGRESS. THE BEST
RADAR ECHOS ARE LINING UP JUST NORTH OF THE RAIN/SNOW LINE AND THE
ACCUMS MAY CONTINUE INTO THE MORNING. WHILE WE MAY NOT REACH THE
CRITERIA AMOUNTS...THERE IS STILL SOME UNCERTAINTY ABOUT THIS TO
KEEP ME FROM LOWERING THE FLAG YET. THE WSW STATEMENT CAN CARRY SOME
SLICK ROADS IMPACTS STATEMENTS TOO. POPS SHOULD LOWER TODAY AS THE
LOW OFF THE EAST COAST BEGINS TO CONSOLIDATE AND MOVE AWAY.
TEMPERATURES MAY WARM ENOUGH BY LATE MORNING...FOR A CHANGE BACK TO
RAIN (OR DRIZZLE) BEFORE ENDING. IT WILL REMAIN CLOUDY THROUGH THE
DAY. TEMPERATURES WILL MOSTLY BE IN THE MID 30S ACROSS THE NORTH AND
UPPER 30S OR MAYBE A FEW LOW 40S ACROSS THE DELMARVA/SRN NJ AND
METRO PHILADELPHIA. WINDS WILL BECOME NORTHERLY BY REMAIN LIGHT THIS
MORNING AND THEN SLOWLY INCREASE BY EVENING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE UPPER TROUGH WILL CROSS THE REGION TONIGHT. A SHARP SFC COLD
FRONT WILL CROSS THE AREA THIS EVENING. IT WILL BE ACCOMPANIED BY
GUSTY WINDS...FALLING TEMPERATURES AND SCATTERED SNOW SHOWERS. A
BETTER CHC FOR THE SNOW SHOWERS WILL BE ACROSS THE DELMARVA CLOSER
TO THE VORT MAX ALONG THE H5 TROUGH. HIGH CHC OR LOW LIKELY POPS
WILL BE OVER THE DELMARVA (AND CHESTER CTY PA) WHILE LOWER CHC POPS
WILL BE OVER THE REST OF PA AND NJ. TEMPERATURES WILL PLUNGE INTO
THE TEENS OVER THE POCONOS...LEHIGH VALLEY AND NRN NJ AND INTO THE
20S ELSEWHERE. WIND CHILL VALUES WILL BE IN THE SINGLE DIGITS WITH
SOME SUB-ZERO READINGS OVER THE SRN POCONOS. WINDS WILL GUST IN THE
25 TO 35 KT RANGE TONIGHT...ESPECIALLY OVER THE SRN COUNTIES.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE FAIRLY SHARP MID LEVEL TROUGH AXIS WILL DEVELOP A NEGATIVE
TILT AS IT LIFTS AWAY FROM OUR AREA ON SUNDAY, AND A SECONDARY
IMPULSE WILL DROP DOWN THE BACK SIDE OF IT AROUND SUNDAY EVENING.
SURFACE PRESSURE RISES IN THE WAKE OF THE TROUGH ARE ROBUST ENOUGH
TO FORECAST LAND WIND GUSTS IN EXCESS OF 30 MPH, BUT MODEL
SOUNDINGS AREN'T PRESENTLY SHOWING A WIND ADVISORY LEVEL FLOW. THE
SECONDARY IMPULSE ALSO CARRIES SOME LESSER PRESSURE RISES IN ITS
WAKE. THE SOUNDINGS ACROSS THE NORTH ARE CAPPED AT ABOUT 7000 FT
AND WE CARRY A CYCLONIC SURFACE FLOW SUNDAY INTO SUNDAY NIGHT, SO
WE CONTINUE TO CARRY FLURRIES NORTH DURING THIS TIME FRAME.
THE MODELS THEN AGREE TO TAKE A MID LEVEL IMPULSE ACROSS THE AREA IN
THE TUESDAY TO WEDNESDAY TIME FRAME, AND THEN START TO DIVERGE ON
THE HANDLING OF ANOTHER AND POSSIBLY MORE ROBUST SYSTEM TOWARD THE
END OF THE WORK WEEK. WE MADE MODEST CHANGES WITH RESPECT TO THE
FORMER AND FOLLOWED CONTINUITY WITH RESPECT TO THE LATTER.
TEMPERATURES WILL START OFF BELOW NORMAL EARLY THIS PERIOD,
TRANSITION TO NORMAL EARLY IN THE WORK WEEK AND THEN GO ABOVE
NORMAL FOR THE LATTER PART OF THE PERIOD.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
LOW CIGS/VSBYS IN SNOW CONTINUE AT THE TERMINALS EARLY THIS MORNING.
AVIATION CONDITIONS WILL START TO IMPROVE BY THE MID-MORNING...LOW
CONFID IN WHETHER CONDITIONS TODAY WILL GET BACK TO VFR OR REMAIN
MVFR. 12Z TAFS MAY INCORPORATE CHANGES TO THE ONGOING TERMINALS. SKY
COVER WILL BE BKN-OVC TODAY WITH MOST OF THE PRECIPITATION ENDING
BEFORE NOON. A SHARP COLD FRONT CROSSES THE TERMINALS THIS EVENING
WITH WINDS SHIFTING NW AND INCREASING WITH 25-30 KT GUSTS OVERNIGHT.
SCATTERED SNOW SHOWERS AND BRIEFLY LOWER CIGS MAY ACCOMPANY THE
FRONT. VFR CONDITIONS WILL RETURN BEHIND THE FRONT.
OUTLOOK...
OUTSIDE OF ANY SNOW SHOWER ACTIVITY THAT MAY OCCUR ON SUNDAY INTO
SUNDAY EVENING (ESPECIALLY NORTHWEST), WE EXPECT VFR CONDITIONS INTO
TUESDAY. THE WEAK WEATHER SYSTEM DURING THE MIDWEEK PERIOD MAY CAUSE
SOME DETERIORATION IN CONDITIONS.
&&
.MARINE...
WE WILL CONVERT THE GALE WATCH TO A WARNING AND EXTEND IT OUT UNTIL
06Z MONDAY.
LOW PRESSURE WILL DEEPEN OFF THE EAST COAST AND TRACK WELL TO OUR
EAST TODAY THROUGH SUNDAY. THE GRADIENT OVER THE WATERS WILL NOT BE
VERY STRONG TODAY...BUT WILL STRENGTHEN SIGNIFICANTLY LATER TODAY
AND REMAIN STRONG INTO EARLY NEXT WEEK. A COLD FRONT WILL CROSS THE
WATERS THIS EVENING AND THE STRONG WIND GUSTS WILL FOLLOW IT. GUSTS
TO 40 KTS ARE POSSIBLE. SCATTERED SNOW SHOWERS WITH LOWER VSBYS MAY
ACCOMPANY THE FRONT. GUSTY WINDS AND ENHANCED SEAS WILL CONTINUE
THROUGH TONIGHT.
GALES ARE EXPECTED TO LAST INTO SUNDAY, AND THEY MAY LINGER INTO
SUNDAY EVENING WITH A SECONDARY FRONT CROSSING THE AREA. AFTER
THAT, CONDITIONS SHOULD DROP TO SUB-ADVISORY AND REMAIN SO THROUGH
THE MIDDLE OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
NONE OF THE LATEST OFS PROGS ARE TAKING ANY OF THE REFERENCE GAUGES
TO WITHIN A HALF FOOT OF THE MINOR TIDAL FLOODING BENCHMARKS. NO
DEPARTURES THIS MORNING WERE MUCH IN EXCESS OF 0.5 FT. WE WILL
CONTINUE TO MONITOR TIDES IN THE EVENT THAT THE PROGS ARE UNDERDONE,
BUT ANY THREAT OF MINOR TIDAL FLOODING WILL DIMINISH ONCE WINDS COME
AROUND TO NORTHWEST. WE THEN WILL TURN OUR CONCERN TO THE POSSIBILITY
OF BLOWOUT TIDES, WHICH ALSO IS DOWNPLAYED BY OFS PROGS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
PAZ070-071.
NJ...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NJZ016>020-027.
DE...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
DEZ001.
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
MDZ008.
MARINE...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST MONDAY
FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...KRUZDLO/DELISI
NEAR TERM...O'HARA
SHORT TERM...O'HARA
LONG TERM...KRUZDLO/DELISI
AVIATION...O'HARA/DELISI
MARINE...O'HARA/DELISI
TIDES/COASTAL FLOODING...DELISI
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