FXUS61 KPHI 092000
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
300 PM EST WED DEC 9 2009
.SYNOPSIS...
INTENSE LOW PRESSURE ACROSS THE GREAT LAKES REGION WILL CAUSE A
STRONG COLD FRONT TO CROSS THE AREA EARLY TONIGHT. STRONG GUSTY
WINDS WILL ACCOMPANY AND FOLLOW THIS FRONT INTO THURSDAY. HIGH
PRESSURE OVER THE PLAINS WILL BUILD EASTWARD THURSDAY AND REMAIN
ACROSS THE AREA INTO THE EARLY PART OF THE WEEKEND. A WEAK
DISTURBANCE MAY AFFECT THE DELMARVA AND SOUTHERN NEW JERSEY LATE
THIS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE STRONG LOW OVER MICHIGAN WILL SEND THE COLD FRONT, PRESENTLY
OVER WEST-CENTRAL PA, ACROSS OUR REGION AFTER DARK. A BAND OF
SHOWERS AND SCATTERED THUNDERSTORMS ARE ATTACHED TO THE FRONT.
ALTHOUGH I DO NOT EXPECT ANY THUNDERSTORMS ACROSS OUR AREA, BUT
SCATTERED SHOWERS AND GUSTY WINDS WILL RETURN TO THE AREA EARLY
TONIGHT. ONCE THE FRONT PASSES BY, CLEARING WILL BEGIN AND GUSTY
WINDS WILL CONTINUE.
A WIND ADVISORY WAS ISSUED EARLIER AND WILL REMAIN IN EFFECT
OVERNIGHT. WIND GUSTS TO AROUND 45 MPH ARE POSSIBLE. THESE WIND
GUSTS ALONG WITH THE SATURATED GROUND MAY CAUSE SOME TREES TO
TOPPLE AND SOME POWER OUTAGES ARE POSSIBLE. LOWS WILL FALL INTO
THE LOW TO MID 30S UP NORTH TONIGHT AND MID TO UPPER 30S ACROSS
THE SOUTH.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
FAIR WEATHER SHOULD PREVAIL IN THE SHORT TERM AS HIGH PRESSURE
BUILDS IN FROM THE PLAINS. WINDS WILL STILL BE GUSTY THURSDAY, AND
THE PRESENT ADVISORY WILL CONTINUE INTO THE DAYTIME HOURS FOR NOW.
LATER SHIFTS CAN ADJUST THE ENDING TIME AS NEEDED. TEMPERATURES
WILL REMAIN 5 TO 10 DEGREES BELOW NORMAL DURING THE SHORT TERM.
SKY COVER SHOULD BE MAINLY CLEAR THROUGH MUCH OF THE SHORT
TERM, HOWEVER SOME CLOUDINESS MAY BE AROUND DURING THE BEGINNING
OF THURSDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE ACTIVE SUBTROPICAL JET COURTESY OF OUR WEEKLY STRONG RATED EL
NINO CONTINUES TO CAUSE FORECASTING PROBLEMS IN THIS RANGE, ONE
BECAUSE IT IS ACTIVE AND TWO BECAUSE ITS COVERING MORE REAL ESTATE
THAN AVERAGE, THUS THE SHORT WAVES ARE COMING ONSHORE AND MOVING
ACROSS THE SOUTHERN CONUS FASTER THAN AVERAGE GIVING LESS FORECAST
LEAD TIME. LONG TERM FORECAST CONFIDENCE WILL REMAIN LESS THAN
AVERAGE.
CASE IN POINT WITH THIS WEEKEND SYSTEM IN WHICH THE GFS AND ECMWF
ARE CURRENTLY STILL ABOUT 24 HOURS APART IN THE ARRIVAL OF
PRECIPITATION, SUNDAY MORNING VS MONDAY MORNING. EVEN THOUGH THERE
ARE TIMING DIFFERENCES, THERE IS A GENERAL MODEL CONSENSUS OF A
GENTLE WAA PATTERN STARTING TO THE WEST OF THE ARCTIC HIGH WITH A
RELATIVELY WEAK LOW PRESSURE SYSTEM EMERGING OFF THE SOUTHERN MIDDLE
ATLANTIC OR SOUTHEAST COAST. WE DID NOT WANT TO PUSH THE START OF
PCPN CHANCES ALL THE WAY TO SUNDAY NIGHT, BUT FOR NOW REMOVED
MENTION FOR SATURDAY NIGHT.
THE AIR MASS WILL START COLD ENOUGH FOR SNOW, ESPECIALLY THE SOONER
IT STARTS AND THEN ANY REMAINING COLD AIR BY SUNDAY NIGHT/MONDAY
WOULD BE PRETTY MUCH CONFINED TO GROUND LEVEL.
ANOTHER ARCTIC COLD FRONT IS FORECAST TO MOVE THROUGH OUR CWA ABOUT
TUESDAY. THE MODELS HAVE BACKED AWAY FROM A MORE VIGOROUS SOUTHERN
STREAM CONTRIBUTOR TO THIS SYSTEM. GIVEN HOW ACTIVE IT HAS BEEN WE
WILL HAVE TO WATCH THIS SOLUTION IN THE DAYS AHEAD. PRECEDING THIS
FRONT THE AIR MASS FOR MUCH OF OUR CWA SHOULD BE WARM ENOUGH FOR
MAINLY RAIN SHOWERS. WE MENTIONED FLURRIES IN THE NW FLOW BEHIND
THIS FRONT FOR OUR NWRN CWA IN THE ARCTIC AIR MASS. MAX TEMPS ON
WEDNESDAY MIGHT BE TOO HIGH PENDING HOW QUICKLY THIS BLAST ARRIVES.
TEMPS IN THE LONG TERM SHOULD AVERAGE BELOW NORMAL AT BOTH ENDS WITH
POSSIBLY SOME MILDER THAN NORMAL TEMPS ON MONDAY AND TUESDAY. AFTER
THE ARCTIC FRONT MOVES THROUGH THE MEDIUM MODELS ARE FORECASTING THE
CONTINUATION OF A RATHER ROBUST -NAO PATTERN WITH A BLOCK INTO
GREENLAND AND A POLAR VORTEX THAT CAME FROM RUSSIA WITH LOVE TO
REACH THE CANADIAN MARITIMES AT THE END OF NEXT WEEK.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
PRIMARY ISSUE WILL BE THE WINDS FOR THE NEXT SEVERAL DAYS ALTO THEY
WILL BE CONSISTENTLY FROM THE WEST. PUBLIC WIND ADVISORIES ARE IN
EFFECT SO SOME OF THE WIND GUSTS TO 40 KTS. OTHERWISE GOOD VFR
CONDITIONS THROUGH SATURDAY.
OUTLOOK...
STORM SYSTEM MOVING NORTH ALONG THE COAST SUNDAY WILL BRING LOWERING
CIGS/VSBYS WITH CATEGORIES OF IFR BY SUNDAY EVENING.
&&
.MARINE...
THE WINDS WILL BE OFFSHORE UNTIL SUNDAY MORNING BUT GALES AND/OR SMALL
CRAFT ADVISORIES WILL BE UP FOR A GOOD PART OF THAT TIME. AS THE LOW
DEPARTS TO THE NORTH HIGH PRESSURE WILL BE BUILDING NORTHEAST FOR
THE NEXT SEVERAL DAYS. THE COLD AIR RUSH BEHIND THE DEEP LOW WILL
KEEP THE LOWER PART OF THE ATMOSPHERE IN TURMOIL AS COLD AIR RUSHES
TO THE COAST. THE GALES WILL BE IN EFFECT AT LEAST THROUGH FRIDAY
MORNING. THE ROUGHEST SEAS WILL BE ACROSS THE LOWER END OF THE
DELAWARE BAY WHILE NEARSHORE SEAS ON THE OCEAN FRONT WILL BE JUST A
COUPLE FEET WITH INCREASING HEIGHTS THE FARTHER OUT YOU GO. GALE
WARNINGS WILL ALSO BE IN EFFECT AT THE CANYONS. THE HIGH PRESSURE
WILL MOVE OFF THE COAST ON SUNDAY WITH A RETURN SOUTH TO SOUTHWEST
FLOW WITH A WEAK LOW MOVING NORTH ALONG THE COAST TO NORTH CAROLINA
BEFORE MOVING FARTHER OFFSHORE.
&&
.HYDROLOGY...
PLENTY OF HYDROLOGICAL ISSUES CONTINUE ACROSS THE AREA FROM LAST
NIGHTS AND THIS MORNINGS HEAVY RAINS. NUMEROUS WARNINGS CONTINUE
AT THE GAGED POINTS. SOME OF THE SLOWER RESPONDING RIVERS MAY NOT
CREST UNTIL THURSDAY. CONSULT THE LATEST PRODUCTS FLS/FLW FROM OUR
OFFICE OR LOOK AT THE AHPS PAGES ON THE WEB FOR THE LATEST.
&&
.TIDES/COASTAL FLOODING...
THE SECONDARY LOW THAT FORMED OVER THE DELMARVA SENT THE TIDAL
DEPARTURES ALONG THE COAST TO NEAR 4 FEET ABOVE NORMAL AT SANDY
HOOK. LUCKILY THIS HAPPENED AT LOW TIDE. WITH THE WINDS NOW SHIFTING
TO THE SOUTHWEST THE DEPARTURES HAVE COME DOWN JUST AT THE TIME OF
HIGH TIDE. NOW...WE GET TO SEE THAT OTHER SIDE OF THE OCEAN...THE
BOTTOM AS THE OFFSHORE WINDS PUSH THE WATER OFFSHORE WITH DEPARTURES
REACHING ABOUT 2 TO 2.5 FEET BELOW NORMAL WITH THE POTENTIAL FOR
BLOWOUT TIDES.
ON THE MAIN-STEM OF THE DELAWARE...WE ARE APPROACHING LOW TIDE BUT
DEPARTURES ARE 4 FEET ABOVE NORMAL. THE NEXT HIGH TIDE WILL OCCUR
THIS EVENING WITH THE WINDS IMPACTING THE TIDES AND LOWERING THE
DEPARTURES TO LEVELS THAT WILL PRODUCE MINOR TIDAL FLOODING.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST THURSDAY FOR
PAZ054-055-060>062-067>071.
COASTAL FLOOD ADVISORY UNTIL 10 PM EST THIS EVENING FOR
PAZ069>071.
NJ...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST THURSDAY FOR
NJZ001-007>010-012>027.
COASTAL FLOOD ADVISORY UNTIL 10 PM EST THIS EVENING FOR
NJZ016>019.
DE...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST THURSDAY FOR
DEZ001>004.
COASTAL FLOOD ADVISORY UNTIL 10 PM EST THIS EVENING FOR DEZ001.
MD...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST THURSDAY FOR
MDZ008-012-015-019-020.
MARINE...GALE WARNING UNTIL 6 AM EST FRIDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...O'HARA
NEAR TERM...O'HARA
SHORT TERM...O'HARA
LONG TERM...GIGI
AVIATION...EBERWINE
MARINE...EBERWINE
HYDROLOGY...O'HARA
TIDES/COASTAL FLOODING...EBERWINE
