000
FXUS61 KPHI 202026
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
420 PM EDT SUN JUL 20 2008
.SYNOPSIS...
TROPICAL STORM CRISTOBAL IS EXPECTED TO PASS WELL TO OUR SOUTHEAST
AND EAST ON MONDAY AND MONDAY NIGHT. MEANWHILE, A FRONTAL BOUNDARY
WILL DROP DOWN FROM THE NORTHWEST AND IT SHOULD REACH EASTERN
PENNSYLVANIA, NEW JERSEY, NORTHEASTERN MARYLAND AND DELAWARE ON
MONDAY. THE BOUNDARY IS FORECAST TO STALL OVER OUR REGION FOR MUCH
OF THE NEW WEEK. IT MAY DISSIPATE TOWARD THE END OF THE WEEK, THEN
ANOTHER FRONTAL BOUNDARY IS ANTICIPATED TO DROP DOWN FROM THE
NORTHWEST FOR NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
WITH A GOOD AMOUNT OF SUNSHINE, TEMPERATURES ROSE INTO THE LOWER AND
MIDDLE 90S THROUGHOUT MUCH OF OUR FORECAST AREA THIS AFTERNOON.
SOME DRIER AIR BEGAN TO MIX DOWN FROM ALOFT AND INTO THE
PHILADELPHIA METROPOLITAN AREA AND POINTS TO THE NORTH AT MID
AFTERNOON. DEW POINT TEMPERATURES BEGAN TO DROP INTO THE LOWER AND
MIDDLE 60S IN SPOTS. NEVERTHELESS, WE HAVE DECIDED TO KEEP THE
EXCESSIVE HEAT WARNING IN EFFECT UNTIL 800 PM.
ISOLATED SHOWERS AND THUNDERSTORMS DEVELOPED OVER DELAWARE BAY AND
SOUTHEASTERN NEW JERSEY DURING THE AFTERNOON. THE REMAINDER OF OUR
FORECAST AREA REMAINED PRECIPITATION FREE. IT LOOKS AS THOUGH NOT
MUCH WILL CHANCE INTO THE VERY EARLY EVENING HOURS.
WE WILL BE LOOKING TO THE WEST, AS SHOWERS AND THUNDERSTORMS
APPROACH FROM THAT DIRECTION. IT APPEARS AS THOUGH THE LEADING EDGE
OF THE PRECIPITATION WILL REACH WESTERN BERKS COUNTY AROUND 730 PM.
THE SHOWERS AND THUNDERSTORMS SHOULD MOVE ACROSS MAINLY THE NORTHERN
AND CENTRAL PARTS OF OUR FORECAST AREA DURING THE FIRST PART OF THE
NIGHTTIME PERIOD. SOME PRECIPITATION MAY LINGER BEYOND MIDNIGHT IN
SPOTS, SO WE DID NOT LIMIT THE MENTION OF RAIN TO JUST THE EVENING
HOURS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
FOR THE LATEST INFORMATION REGARDING TROPICAL STORM CRISTOBAL,
PLEASE REFER TO THE LATEST STATEMENTS FROM THE NATIONAL HURRICANE
CENTER.
DURING THE SHORT TERM PERIOD, THE UPPER FLOW WILL BEGIN AS ZONAL,
WITH A TROUGH EVENTUALLY BEGINNING TO DIG OVER THE GREAT LAKES AND
NORTHEAST, AS A RIDGE BEGINS TO BUILD OVER THE GREAT PLAINS.
A FRONTAL BOUNDARY FROM THE NORTHWEST IS EXPECTED TO DROP INTO OUR
REGION FROM THE NORTHWEST ON MONDAY. WHILE IT WILL REMAIN QUITE
WARM, A WESTERLY WIND SHOULD HELP TO MIX DOWN SOME DRIER AIR DURING
THE AFTERNOON HOURS, CAUSING DEW POINT TEMPERATURES TO DROP INTO THE
LOWER AND MIDDLE 60S. AS A RESULT, HEAT INDEX VALUES SHOULD ONLY
REACH THE MIDDLE 90S IN THE PHILADELPHIA METROPOLITAN AREA.
THEREFORE, WE WILL NOT NEED TO EXTEND THE EXCESSIVE HEAT WARNING.
EVEN WITH THE FRONTAL BOUNDARY IN THE REGION, IT APPEARS AS THOUGH
ANY SHOWERS AND THUNDERSTORMS ON MONDAY AFTERNOON AND EVENING WILL
BE ISOLATED. AS A RESULT, WE HAVE NOT MENTIONED THEM IN THE
FORECAST AT THIS TIME.
THE WEATHER SHOULD REMAIN RATHER QUIET FROM MONDAY NIGHT INTO EARLY
TUESDAY.
A WEAK WAVE OF LOW PRESSURE MAY RIDE ALONG THE FRONTAL BOUNDARY ON
TUESDAY NIGHT AND WEDNESDAY, INCREASING THE CHANCES FOR SHOWERS AND
THUNDERSTORMS. WITH THE POTENTIAL FOR A LITTLE MORE CLOUD COVER
EACH DAY, A SLIGHT COOLING TREND IS EXPECTED FOR TUESDAY AND
WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE UPPER PATTERN FEATURING A TROUGH OVER THE EAST WITH A RIDGE OVER
THE WEST SHOULD REMAIN IN PLACE DURING THE LONG TERM PERIOD OF THE
FORECAST, HELPING TO PREVENT THE DEVELOPMENT OF ANOTHER HEAT WAVE.
PRECIPITATION ASSOCIATED WITH THE FRONTAL BOUNDARY AND THE PASSING
WAVE OF LOW PRESSURE ARE EXPECTED TO LINGER INTO WEDNESDAY NIGHT.
EVEN THOUGH THE FRONTAL BOUNDARY IS EXPECTED TO LINGER OVER OR NEAR
THE REGION FOR THURSDAY AND FRIDAY, IT SHOULD BEGIN TO DISSIPATE.
ISOLATED SHOWERS AND THUNDERSTORMS ARE NOT OUT OF THE QUESTION,
ESPECIALLY ON THE COASTAL PLAIN. FOR THE MOST PART, WE WILL LEAVE
THEM OUT OF THE FORECAST FOR NOW.
ANOTHER FRONT IS EXPECTED TO DROP DOWN FROM THE NORTHWEST, WITH
INCREASING CHANCES FOR PRECIPITATION ON FRIDAY NIGHT AND SATURDAY.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL REMAIN OVER THE REGION EARLY IN THE PERIOD AND
VFR CONDITIONS ARE EXPECTED. THERE WILL BE SOME ISOLATED TO
SCATTERED EVENING THUNDERSTORMS THAT COULD REDUCE VSBYS AND CIGS TO
IFR/MVFR. HOWEVER, WILL NOT MENTION IN INDIVIDUAL TAF SITES AS IT
IS DIFFICULT TO TIME AND LOCATE THE DIURNAL CONVECTION. WILL
CONTINUE TO MENTION CB. A COLD FRONT WILL APPROACH THE AREA ON
MONDAY THEN STALL INVOF THE REGION. THERE WILL BE SOME ADDITIONAL
ISOLD TSRAS ON MONDAY AS WELL, BUT AGAIN WILL NOT MENTION AT
INDIVIDUAL SITES DUE TO RELATIVELY SMALL AREAL COVERAGE.
OUTLOOK...
THE COLD FRONT THAT STALLS NEAR THE AREA MAY ACT AS A TRIGGER FOR
DIURNAL TSRA THROUGH MIDWEEK. THERE COULD BE ADDITIONAL CIG/VSBY
RESTRICTIONS WITH ANY TSRA.
&&
.MARINE...
AT THE BEGINNING OF THE PD, HIGH PRESSURE WILL BE IN CONTROL.
HOWEVER, SEVERAL FEATURES WILL AFFECT THE MARINE AREA THROUGH
MIDWEEK. SWELLS FROM BERTHA WILL CONTINUE TO DECREASE AS THE SYS
MOVES FURTHER AWAY IN THE OPEN ATLC.
HOWEVER, AS T.S. CRISTOBAL MOVES NEWD, SWELLS WILL INCREASE BY
MONDAY AND CONTINUE INTO MIDWEEK. AT THE SAME TIME, A COLD FRONT
WILL MOVE ACROSS THE REGION ON MONDAY AND THEN STALL INVOF THE AREA.
WAVEWATCH HAS REALLY INCREASED SEAS AS A RESULT OF INCREASING SWLY
FLOW AHEAD OF A LOW PRES SYS. HOWEVER, THE GFS AND WAVEWATCH APPEAR
TO BE OVERDONE WITH THIS AS THE GFS IS CLEARLY SUFFERING SOME
FEEDBACK PROBLEMS. SO, WILL INCREASE SEAS A BIT, BUT NOT NEARLY AS
MUCH AS THE GFS. CURRENT FCST WINDS DO NOT SUPPORT SEAS AS HIGH AS
THE GFS INDICATES. ADDITIONALLY, CRISTOBAL`S AFFECT ON THE REGION
SHOULD BE LONG PAST AT THAT TIME.
RIP CURRENTS...
SWELLS ARE EXPECTED TO REDEVELOP A LONGER PERIOD AGAIN IN RESPONSE
TO TROPICAL STORM CRISTOBAL, WHICH WAS EAST OF THE CAROLINA COAST.
CRISTOBAL IS EXPECTED TO HEAD TOWARD THE NORTHEAST AND WELL EAST OF
THE NEW JERSEY AND DELAWARE COASTS MONDAY NIGHT. THIS MAY BRING A
CONSEQUENT INCREASE IN THE RIP CURRENT RISK TO THE AREA.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...EXCESSIVE HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR
PAZ067>071.
NJ...EXCESSIVE HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR NJZ015-
017>019.
DE...EXCESSIVE HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR DEZ001.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS/NEAR TERM/SHORT TERM/LONG TERM...IOVINO
AVIATION/MARINE...NIERENBERG
