107
FXUS61 KPHI 042303
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
703 PM EDT SAT JUL 4 2009
SYNOPSIS
BROAD LOW PRESSURE, LOCATED OVER THE LOWER SAINT LAWRENCE RIVER
VALLEY THIS EVENING, WILL CONTINUE TO MOVE TO THE EAST. MEANWHILE,
WEAK HIGH PRESSURE WILL REMAIN OVER OUR REGION INTO THE EARLY PART
OF THE NEW WEEK. ANOTHER AREA OF LOW PRESSURE, LOCATED OVER
MISSOURI THIS AFTERNOON, WILL PROGRESS TO THE EAST AND IT SHOULD
PASS OFF THE COASTS OF VIRGINIA AND NORTH CAROLINA EARLY ON
MONDAY. A WEAK FRONTAL BOUNDARY FROM THE NORTHWEST IS EXPECTED TO
ARRIVE ON MONDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THE MIDDLE
AND LATE PARTS OF THE NEW WEEK. A COLD FRONT FROM THE NORTHWEST IS
FORECAST TO ARRIVE LATE ON SATURDAY.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
AT 645 PM, THE CLOUDS ARE INCHING THEIR WAY INTO THE WEST AND
SOUTHWEST PART OF THE FORECAST REGION. SEVERAL LAYERS ARE SHOWING
UP EVEN OUTSIDE OUR WINDOWS BUT THINK THE THICKENING PART WILL
REMAIN TO THE SOUTHWEST. TEMPERATURES WERE FALLING INTO THE 70S
AND UPPER 60S.
THE GRADIENT HAS BEEN THE STORY TODAY WITH COLD AIR MOVING IN AT
80H THROUGH THE AFTERNOON WITH GUSTY WINDS AND NOW WAA IN RESPONSE
TO WAVE MOVING INTO VIRGINIA.
WE LOOK FOR THE EARLIER FORECAST TREND TO CONTINUE, I.E. MOSTLY
CLOUDY OUR SOUTHERN COUNTIES, AND PARTLY CLOUDY UP NORTH.
THE NAM AND THE GFS HAVE BEEN EXHIBITING SOME DIFFICULTY IN HANDLING
THE EASTWARD PROGRESS OF THE CONVECTION THAT WAS IN THE MIDDLE
MISSISSIPPI RIVER VALLEY THIS AFTERNOON. THE LATEST GUIDANCE
SUGGESTED THAT THE CHANCE FOR PRECIPITATION TONIGHT WILL BE VERY LOW
FOR OUR FAR SOUTHERN COUNTIES AND NONEXISTENT FOR THE CENTRAL AND
NORTHERN PARTS OF OUR AREA. AS A RESULT, WE WILL SIMPLY CARRY
SLIGHT CHANCE POPS FOR SOUTHERN DELAWARE AND FOR THE MARYLAND
COUNTIES OF TALBOT AND CAROLINE.
SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
THE UPPER LEVEL TROUGH IS EXPECTED TO REMAIN OVER THE NORTHEASTERN
STATES FOR SUNDAY, MONDAY AND TUESDAY, WITH A REINFORCING SHORT WAVE
EXPECTED TO DROP DOWN FROM THE NORTHWEST EARLY IN THE NEW WEEK.
THE REMNANTS OF THE CONVECTIVE COMPLEX FROM THE WEST AND ITS
ASSOCIATED SURFACE LOW SHOULD PASS OFF THE COAST AROUND SOUTHERN
VIRGINA AND NORTHERN NORTH CAROLINA EARLY ON MONDAY. OUR SOUTHERN
COUNTIES WILL LIKELY BE ON THE NORTHERN EDGE OF THE SYSTEMS'S
PRECIPITATION SHIELD ON SUNDAY NIGHT. WITH CONDITIONS OVER OUR
REGION EXPECTED TO BE STABLE AT THAT TIME, WE HAVE SIMPLY MENTIONED
A CHANCE OF SHOWERS. AGAIN OUR CENTRAL AND NORTHERN COUNTIES SHOULD
REMAIN DRY.
WITH WEAK IMPULSES MOVING ALONG THE UPPER TROUGH, WE MAY SEE SPOTTY
SHOWERS DURING THE AFTERNOON AND EARLY EVENING HOURS ON MONDAY AND
TUESDAY, ESPECIALLY IN EASTERN PENNSYLVANIA AND IN NORTHERN AND
CENTRAL NEW JERSEY. FOR NOW, WILL HAVE INCLUDED SLIGHT CHANCE
POPS. IT SEEMS AS THOUGH INSTABILITY WILL BE LIMITED AT THOSE
TIMES, SO ANY LIGHTNING ACTIVITY MAY BE RATHER ISOLATED.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
IT LOOKS AS THOUGH WE WILL LOSE THE UPPER LEVEL TROUGH BRIEFLY
DURING THE LATE PART OF THE WEEK. HOWEVER, BOTH THE GFS AND THE
ECMWF SUGGEST ITS RETURN DURING THE COURSE OF NEXT WEEKEND, ALTHOUGH
IT MAY NOT BE AS PRONOUNCED AS THE CURRENT ONE.
SURFACE HIGH PRESSURE IS EXPECTED TO BUILD INTO OUR REGION FROM THE
WEST ON WEDNESDAY. THE CENTER OF THE HIGH SHOULD PASS OVER OR NEAR
OUR REGION ON THURSDAY, BEFORE MOVING OUT TO SEA ON FRIDAY. WE WILL
FORECAST DRY WEATHER FOR EACH OF THE THREE DAYS.
A COLD FRONT IS ANTICIPATED TO DROP DOWN FROM THE NORTHWEST ON
SATURDAY, AS AN UPPER LEVEL TROUGH AGAIN BEGINS TO ESTABLISH ITSELF
OVER THE EASTERN STATES. WE WILL INCLUDE A CHANCE FOR AFTERNOON AND
EVENING THUNDERSTORMS.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
HIGH PRESSURE IS IN CONTROL OF THE WX OVER THE MID-ATLC AND
GENERALLY PLEASANT WX IS IN STORE. VFR CONDS WILL PREVAIL THROUGH
THE TAF PD. THERE WILL BE SOME FAIR WX CU AND SOME HIGH CLOUDS AND
THAT IS ABOUT IT. HOWEVER, GUSTY W TO NW WINDS WILL CONTINUE
THROUGH THE EVENING. GUSTS TO 20 KT ARE LIKELY AND A FEW GUSTS TO
25 KT ARE PSBL.
OUTLOOK...
VFR CONDITIONS WILL CONTINUE INTO SUNDAY, BUT A DISTURBANCE IS FCST
TO PASS TO THE SOUTH LATE SUNDAY AND SUNDAY NIGHT. THIS SYSTEM WILL
BRING THE CHC OF SHOWERS TO THE DELMARVA AND PSBLY TO SRN NJ AND
SERN PA. THE MOST LIKELY PLACES TO SEE PRECIP WOULD BE KACY AND
KMIV. HOWEVER, AMTS ARE EXPECTED TO BE LIGHT. NONETHELESS, THERE
COULD BE SOME MVFR IN ANY HEAVIER RAIN, BUT THE CHANCES OF MVFR
APPEAR SMALL ATTM. WK HIGH PRESSURE THEN BUILDS BACK IN FOR LATER
MONDAY INTO MIDWEEK, BRINGING GENLY VFR CONDS. THE ONLY CAVEAT IS,
THERE WILL BE YET ANOTHER UPR LOW TO OUR NORTH AND AS THIS SYS
SPINS, IT CAN SEND SOME RIPPLES THROUGH WHICH WOULD BRING SOME ISOLD
TO SCT DIURNAL CONVECTION. CERTAINLY, AT THIS TIME, IT IS DIFFICULT
TO DETERMINE WHERE AND ON WHICH DAYS ANY PRECIP CHCS WOULD BE
GREATEST.
MARINE
WK HIGH PRESSURE OVER THE REGION HAS BROUGHT GENLY NICE WX TO THE
MARINE AREA FOR THE HOLIDAY WEEKEND. THE ONLY FLY IN THE OINTMENT
IS SOME GUSTS W TO NW WINDS, GENLY TO ABOUT 20 KTS. THERE COULD BE A
GUST OR TWO TO 25 KT, BUT CHCS APPEAR FAIRLY LOW FOR THAT. SEAS ARE
GENLY EXPECTED TO BE IN THE 2 TO 3 FT RANGE.
THE RIP CURRENT RISK WILL CONTINUE TO BE LOW, DESPITE THE LONG
PERIOD ON THE WAVES AND THE NEARING OF THE FULL MOON ON TUESDAY.
A WX DISTURBANCE WILL PASS TO THE S LATER SUNDAY INTO SUNDAY NIGHT.
THIS MAY BRING SOME SCT SHWRS TO THE SRN MARINE ZONES, BUT LITTLE
ELSE.
YET ANOTHER UPPER LOW BUILDS DOWN FROM THE N ON MONDAY WITH WK HIGH
PRES AT THE SFC. GENLY DRY WX IS EXPECTED, WITH THE EXCEPTION OF
SOME ISOLD TO SCT DIURNAL CONVECTION WITH ANY RIPPLES WHICH ROTATE
THROUGH THE LOW.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...IOVINO/EBERWINE
NEAR TERM...IOVINO/EBERWINE
SHORT TERM...IOVINO
LONG TERM...IOVINO
AVIATION...NIERENBERG
MARINE...NIERENBERG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page