328
FXUS61 KPHI 111405
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1005 AM EDT THU AUG 11 2022
SYNOPSIS
A STATIONARY FRONT WILL REMAIN IN PLACE TODAY ACROSS THE
DELMARVA WHILE A WAVE OF LOW PRESSURE RIDES ALONG IT OUT TO SEA.
A STRONGER COLD FRONT WILL THEN CROSS OUR REGION TONIGHT INTO
FRIDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION FOR SATURDAY
BEFORE WEAKENING SUNDAY. ANOTHER STORM SYSTEM WILL ARRIVE EARLY
NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
ONLY SIGNIFICANT CHANGE TO THE FORECAST FOR THE MID-MORNING
UPDATE WAS TO HOLD ONTO SOME ISOLATED POPS FOR A FEW MORE HOURS
MAINLY OVER THE DELMARVA WHERE A COUPLE SHOWERS ARE HANGING
BACK. OTHERWISE, INHERITED FORECAST IS ON TRACK.
..4AM DISCUSSION
THE SURFACE COLD FRONT WHICH STALLED ACROSS THE SOUTHERN ZONES
THIS AFTERNOON HAS SINCE RETREATED NORTH AS A WARM FRONT AS A
700/ 500 MB SHORTWAVE RIPPLES EAST ALONG THE BOUNDARY. IN
RESPONSE TO THE SHORTWAVE, CONVECTION HAS BEEN TRACKING EAST
ALONG THE PA/ MD BORDER THIS MORNING AND IS CURRENTLY
APPROACHING THE I-95 CORRIDOR. AS THE SHORTWAVE EXITS EAST THIS
MORNING, A WEAK COLD FRONT WILL SLIP OFF THE DE AND NJ COAST
WITH DEWPOINTS FALLING INTO THE LOWER 60S. THE PRIMARY COLD
FRONT WILL BE HELD BACK AS THE LONGWAVE TROUGH AXIS REMAINS
CENTERED OVER THE OHIO RIVER VALLEY. LATER THIS AFTERNOON A
SEABREEZE WILL START TO PUSH INLAND AROUND 10 TO 20 MILES AND
QUICKLY COME TO A HALT. SOME HIGH RES GUIDANCE IS INDICATING
THAT AN ISOLATED SHOWER AND THUNDERSTORM WILL BE POSSIBLE ALONG
THE SEA BREEZE, BUT PWATS DO FALL OFF TO AROUND 1.10” WITH A
SIGNIFICANT DRY SLOT MOVING OVERHEAD AS WELL. GIVEN THE ABOVE,
DRY AIR ENTRAINMENT WILL LIKELY KEEP MOST UPDRAFTS IN CHECK, BUT
AN ISOLATED SHOWER AND THUNDERSTORM CAN’T BE RULED OUT
(ESPECIALLY NEAR THE COAST). TEMPERATURES TODAY WILL LIKELY
AGAIN BE WARM, WITH HIGHS APPROACHING OR JUST TOUCHING THE 90
DEGREE MARK.
THIS EVENING, THE PRIMARY COLD FRONT WILL APPROACH THE AREA
FROM THE NORTHWEST AS THE LONGWAVE TROUGH AXIS PROGRESSES EAST.
THE FRONT WILL MOSTLY BE A DRY FRONTAL PASSAGE WITH DEWPOINTS
FALLING INTO THE UPPER 50S FOR MOST OF THE AREA BY FRIDAY
MORNING.
SHORT TERM /FRIDAY THROUGH SUNDAY/
THE CORE OF THE DCVA WILL TRANSLATE OVERHEAD FRIDAY WITH SKIES
BEGINNING TO SLOWLY CLEAR DURING THE DAY AND TEMPERATURES MUCH
COOLER WITH LOWER HUMIDITY VALUES. EXPECT HIGH TEMPERATURES IN
THE LOW 80S FRIDAY WITH NO PRECIPITATION EXPECTED. ON SATURDAY,
THE SHORTWAVE EMBEDDED IN THE LONGWAVE TROUGH AXIS WILL WRAP UP
INTO A CLOSED LOW ACROSS NEW ENGLAND ALLOWING FOR THE DELAWARE
RIVER VALLEY TO FALL INTO THE AGEOSTROPHIC CONVERGENT SIDE OF
THE TROUGH AXIS. EXPECT MOSTLY CLEAR SKIES WITH HIGHS IN THE
LOWER 80S AND RELATIVE HUMIDITY VALUES IN THE LOWER 30% RANGE.
ON SUNDAY, THE SURFACE HIGH PRESSURE THAT WAS OVERHEAD ON
SATURDAY WILL BEGIN TO LOSE COHESION AS THE AGEOSTROPHIC
CONVERGENCE COLLAPSES DUE TO AN IMPINGING SHORTWAVE DIVING
SOUTHEAST OUT OF THE GREAT LAKES REGION. GLOBAL MODELS ARE
INDICATING PRECIPITATION MOVING INTO THE REGION SUNDAY
AFTERNOON, BUT UPON FURTHER INVESTIGATION OF FORECAST SOUNDINGS
AM NOT SO SURE. COMPLETE SATURATION ABOVE 600 MB IS FORECAST,
BUT IN THE LOW LEVELS DEW POINT DEPRESSIONS ARE FORECAST TO BE
LARGE. DUE TO THIS, I HAVE KEPT MOST OF THE REGION DRY THROUGH
THE DAY SUNDAY. EXPECT HIGH TEMPERATURES IN THE LOW TO MID 80S.
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
THE LONG TERM PERIOD LOOKS TO BE DEFINED BY A SIGNIFICANT
PATTERN CHANGE FOR NEXT WEEK. ENSEMBLE AND DETERMINISTIC
GUIDANCE CONTINUES TO HINT AT A LONGWAVE TROUGH SETTING UP OVER
THE EASTERN US, WHICH WOULD BRING BELOW AVERAGE TEMPERATURES AND
THE POTENTIAL FOR SOME MUCH NEEDED RAIN.
GETTING INTO THE DAY-BY-DAY PORTION OF THE DISCUSSION, A
SHORTWAVE WILL SWING THROUGH LATE SUNDAY NIGHT/EARLY MONDAY
MORNING. AT THE SURFACE, AN AREA OF LOW PRESSURE LOOKS TO
DEVELOP OVER THE OHIO RIVER VALLEY, INCHING TOWARD OUR AREA
GETTING INTO MONDAY. THIS WILL RESULT IN A RATHER WET AND
UNSETTLED MONDAY. HAVE GONE LIKELY POPS FOR MOST OF THE REGION
AS SOME NEEDED RAIN LOOKS TO MOVE THROUGH MONDAY AFTERNOON AND
EVENING. SEVERE THREAT LOOKS RATHER LIMITED, THOUGH WE WILL HAVE
TO MONITOR THE POTENTIAL HYDRO THREAT. CONFIDENCE IS QUITE HIGH
THAT TEMPERATURES WILL BE BELOW NORMAL, WITH HIGHS AROUND 80
FOR DELMARVA, PHILADELPHIA, AND THE NJ COASTAL PLAIN. LOOKING AT
UPPER 70S NORTH AND WEST OF PHILADELPHIA, WITH TEMPERATURES IN
THE POCONOS POTENTIALLY NOT GETTING OUT OF THE 60S.
DETERMINISTIC GUIDANCE REMAINS PRETTY CONSISTENT IN A STRONG
SHORTWAVE MOVING IN FROM THE NORTH, WITH A CLOSED LOW EVENTUALLY
FORMING AT 500 MB LATE MONDAY/EARLY TUESDAY. STILL SOME
UNCERTAINTY IN HOW FAR SOUTH THE CLOSED LOW GETS, BUT THERE IS
INCREASING CONFIDENCE ON ANOTHER MILD AND UNSETTLED DAY ON
TUESDAY. HAVE HIGH END CHC AND LOW END LIKELY POPS FOR TUESDAY
AS THE SURFACE LOW COULD SLIDE THROUGH THE SOUTHERN PORTION OF
OUR CWA. WITH THE MEANDERING 500 MB LOW REMAINING CLOSE BY, THE
SURFACE LOW IS EXPECTED TO TRACK SLOWLY NORTHEASTWARD AWAY FROM
THE NJ COAST, LIKELY BRINGING ANOTHER WET AND MILD DAY ON
WEDNESDAY. WITH THE RATHER SLOW MOVEMENT OF THE SURFACE LOW,
THERE COULD BE A PROLONGED PERIOD OF ONSHORE FLOW, WHICH COULD
RESULT IN SOME COASTAL FLOODING. CONFIDENCE IS LOW IN ANY
SPECIFIC IMPACTS AT THIS TIME, BUT WILL BECOME MORE CLEAR AS WE
GET CLOSER. BOTH TUESDAY AND WEDNESDAY WILL FEATURE TEMPERATURES
IN THE MID TO UPPER 70S, SOMETHING NOT SEEN IN QUITE SOME TIME
AROUND HERE. OVERALL, EARLY NEXT WEEK WILL FEATURE SOME GOOD
RAIN CHANCES TO HELP THE REGION WITH THE ONGOING DROUGHT
CONCERNS.
AVIATION /14Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY... VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF THE
DAY. NORTHWESTERLY WINDS AROUND 5-10 KTS. AN ISOLATED SHOWER IS
POSSIBLE. HIGH CONFIDENCE IN PREVAILING VFR CONDITIONS.
TONIGHT...VFR. NORTHERLY WINDS AROUND 5-10 KTS. HIGH
CONFIDENCE.
OUTLOOK…
FRIDAY THROUGH SATURDAY...VFR. NORTHERLY WINDS 5-10 KTS. SOME
GUSTS UP TO 20 KTS POSSIBLE ON FRIDAY. HIGH CONFIDENCE.
SUNDAY…VFR. SOUTHWEST WINDS 5-10 KTS. HIGH CONFIDENCE.
MONDAY...PREVAILING VFR, BUT SCATTERED SHOWERS AND
THUNDERSTORMS MAY INTRODUCE SOME BRIEF RESTRICTIONS. SOUTHERLY
WINDS 5-10 KTS. MODERATE CONFIDENCE.
MARINE
NO MARINE HEADLINES ANTICIPATED THROUGH TONIGHT. WESTERLY WINDS
5-10 KTS THIS MORNING WILL SHIFT SOUTH TO SOUTHWESTERLY THIS
AFTERNOON. WINDS WILL SHIFT TO THE NORTH OVERNIGHT AROUND 15 KTS
WITH GUSTS UP TO 20 KTS. SEAS AROUND 2 FEET.
A CLUSTER OF HEAVY SHOWERS AND THUNDERSTORMS WILL MOVE OFF OF
THE NEW JERSEY COAST THROUGH MID-MORNING. OTHERWISE, FAIR
WEATHER IS EXPECTED WITH AN ISOLATED SHOWER OR THUNDERSTORM
POSSIBLE THROUGH TONIGHT.
OUTLOOK...
FRIDAY THROUGH SATURDAY...NO MARINE HEADLINES ANTICIPATED.
NORTH TO NORTHEASTERLY WINDS 10-15 KTS WITH GUSTS UP TO 20 KTS.
SEAS 2-3 FEET. FAIR WEATHER.
SUNDAY THROUGH MONDAY...NO MARINE HEADLINES ANTICIPATED. WINDS
WILL SETTLE OUT OF THE SOUTH AROUND 10-15 KTS. SEAS 2-3 FEET.
SCATTERED SHOWERS AND THUNDERSTORMS ON MONDAY.
RIP CURRENTS...
WINDS WILL START OFFSHORE IN THE MORNING THEN SHIFT ONSHORE INTO
THE AFTERNOON AROUND 10 MPH. BREAKING WAVES OF 1-2 FEET WITH A
MEDIUM SOUTH TO SOUTHWEST SWELL WILL RESULT IN A LOW RISK OF RIP
CURRENTS.
A NORTHERLY WIND AROUND 15-20 MPH IS EXPECTED ON FRIDAY. THIS
COMBINED WITH A BUILDING NORTHERLY SWELL AND BREAKERS OF 2-3 FEET
WILL RESULT IN A LOW RISK OF RIP CURRENTS.
TIDES/COASTAL FLOODING
THE FULL MOON OCCURS THIS EVENING. THE EVENING HIGH TIDES TODAY
AND FRIDAY WILL BE PARTICULARLY HIGH EVEN WITHOUT ANY CONTRIBUTION
FROM THE WIND.
WHILE SOME LOCALIZED TIDAL FLOODING OCCURRED LAST EVENING IN
THE COASTAL COUNTIES OF NEW JERSEY AND DELAWARE, AND ALONG
DELAWARE BAY, THE MINOR TIDAL FLOODING MAY BECOME MORE
WIDESPREAD BOTH THIS EVENING AND FRIDAY EVENING. THE LATEST
FORECAST GUIDANCE SUGGESTS THAT WE MAY NEED ADVISORIES FOR PARTS
OF OUR REGION AT THOSE TIMES.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...RCM
NEAR TERM...HAINES/RCM
SHORT TERM...HAINES
LONG TERM...HOEFLICH
AVIATION...STAARMANN/RCM
MARINE...STAARMANN
TIDES/COASTAL FLOODING...WFO PHI
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