Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 282215
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
615 PM EDT TUE JUL 28 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE OFF THE COAST ON WEDNESDAY GIVING WAY TO A
WEAK COLD FRONT PASSAGE ON THURSDAY INTO FRIDAY MORNING. ANOTHER
WEAK FRONT MAY CROSS THE REGION SUNDAY INTO MONDAY FOLLOWED BY A
BRIEF SHOT OF HIGH PRESSURE. AFTER THE RESPITE OF HIGH PRESSURE A
STRONGER COLD FRONT IS EXPECTED TO PASS THROUGH ON TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
UPDATED POPS, WEATHER AND SKY GRIDS BASED ON THE LATEST RADAR AND
SATELLITE TRENDS JUST AFTER 530 PM. A STATIONARY BOUNDARY WAS
LOCATED NEAR I-95 LATE THIS AFTERNOON. ANY SHOWERS AND STORMS
EARLY THIS EVENING STILL LOOKS TO BE CONFINED TO THE SOUTH AND
EAST OF THIS BOUNDARY, WHERE HIGHER DEWPOINTS AND INSTABILITY
EXISTS. THE COVERAGE WILL BE MAINLY ISOLATED. ADDITIONAL
CONVECTION IS BEING FOCUSED ALONG THE SEA-BREEZE FRONT IN SOUTHERN
NJ AND SOUTHERN DELAWARE. HIGHER POPS WERE PLACED IN THERE THRU
SUNSET. THESE STORMS ARE SLOW-MOVERS (AS ALL STORMS HAVE BEEN THIS
WEEK), SO THERE IS ONCE AGAIN A LOCALLY HEAVY RAINFALL WITH
ISOLATED 1-2 INCHES PER HOUR CAPABLE OF POOR DRAINAGE FLOODING.

PREVIOUS DISCUSSION...

OTHERWISE, SCATTERED CUMULUS SHOULD DISSIPATE GRADUALLY DURING THE
EVENING HOURS. WHILE SOME PATCHY LOW CLOUDS, HAZE AND LIGHT FOG MAY
DEVELOP LATE TONIGHT THE MODEL GUIDANCE SUGGESTS THAT IT SHOULD NOT
BE AS WIDESPREAD AS IT WAS THIS MORNING.

A MID LEVEL RIDGE IS FORECAST TO EXTEND FROM THE SOUTH CENTRAL
STATES UP ACROSS THE GREAT LAKES TO EASTERN ONTARIO AND WESTERN
QUEBEC TONIGHT. THE RIDGE IS EXPECTED TO KEEP OUR AREA RAIN-FREE FOR
TONIGHT.

MINIMUM TEMPERATURES ARE ANTICIPATED TO BE MAINLY IN THE UPPER 60S
AND LOWER 70S WITH A LIGHT SOUTHWEST TO SOUTH SURFACE FLOW.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
THE AXIS OF THE MID LEVEL RIDGE IS FORECAST TO DRIFT EASTWARD AND IT
SHOULD APPROACH OUR REGION LATE ON WEDNESDAY. AS A RESULT, THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL BE EVEN LOWER THAN IT
WAS TODAY. WE ARE EXPECTING A MOSTLY SUNNY SKY FOR WEDNESDAY WITH
SOME CIRRUS OVERHEAD ALONG WITH THE DEVELOPMENT OF SCATTERED CUMULUS.

MAXIMUM TEMPERATURES ARE FORECAST TO RANGE FROM 90 TO 95 IN MUCH OF
OUR REGION. READINGS SHOULD GET NO HIGHER THAN THE MIDDLE AND UPPER
80S IN THE ELEVATED TERRAIN UP NORTH AND ALONG THE IMMEDIATE COAST.

IT APPEARS AS THOUGH SLIGHTLY DRIER AIR WILL MIX TO THE SURFACE FROM
ALOFT FOR WEDNESDAY AFTERNOON. DEW POINT READINGS ARE EXPECTED TO
FAVOR THE MIDDLE 60S ON WEDNESDAY AFTERNOON, EXCEPT IN DELAWARE AND
NORTHEASTERN MARYLAND WHERE THE BAYS SHOULD HELP KEEP DEW POINT
READINGS IN THE UPPER 60S AND LOWER 70S.

THE COMBINATION OF TEMPERATURE AND DEW POINT IS ANTICIPATED TO RESULT
IN MAXIMUM HEAT INDEX VALUES BEING NEAR OR A DEGREE OR TWO ABOVE THE
MAXIMUM AIR TEMPERATURES IN EASTERN PENNSYLVANIA AND NEW JERSEY. THE
IMPACT OF THE HIGHER HUMIDITY ON THE DELMARVA SHOULD BRING MAXIMUM
HEAT INDEX VALUES SOLIDLY INTO THE UPPER 90S THERE WITH PERHAPS A
FEW SPOTS HITTING 100, ESPECIALLY SOUTH OF THE CANAL.

WE WILL NOT BE ISSUING A HEAT ADVISORY OR AN EXCESSIVE HEAT WARNING
AT THIS TIME SINCE ALL LOCATIONS IN OUR FORECAST AREA ARE EXPECTED
TO REMAIN JUST BELOW THE ISSUANCE CRITERIA.

A SOUTHWEST TO SOUTH WIND AROUND 5 TO 10 MPH IS EXPECTED FOR
WEDNESDAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
5-WAVE MODEL GUIDANCE SHOWS SOUTHEAST RIDGING GIVING WAY TO A
DEVELOPING TROUGH ACROSS THE NORTHEASTERN HALF OF THE CONUS BY THE
WEEKEND. A FEW IMPULSES WILL TRAVERSE THROUGH THE BASE OF THE TROUGH
NEXT WEEK PROVIDING CHANCES FOR MORE UNSETTLED WEATHER EARLY NEXT
WEEK.

THURSDAY...INCREASING MOISTURE FLUX AHEAD OF THE WEAKENING COLD
FRONT MAY BRING IN MORE CLOUD COVER THAN PREVIOUSLY EXPECTED. THERE
COULD BE ENOUGH INSTABILITY ADVECTING IN ALOFT TO SPARK SCATTERED
SHOWERS WITH EMBEDDED THUNDER DURING THE MORNING HOURS, MOSTLY
ACROSS THE SOUTH AND WEST, TO KEEP TEMPERATURES FROM REALLY PEAKING
AS HIGH AS PREVIOUSLY THOUGHT, THOUGH LOW-90S IS NOTHING TO SNEEZE
AT. THERE WILL BE SOME ENHANCED VERTICAL MIXING DURING THE AFTERNOON
WHICH SHOULD KEEP DEWPOINTS FROM STAYING IN THE LOW-70S, SO
EXPECTING THEM TO MIX OUT INTO THE UPPER-60S...SHOULD KEEP HEAT
INDEX VALUES JUST BELOW ADVISORY CRITERIA BUT STILL HAVE SOME TIME
FOR FURTHER ASSESSMENT. BESIDES THE HEAT, THE APPROACH OF THE COLD
FRONT LATER IN THE AFTERNOON, WILL TRIGGER MORE SCATTERED SHOWERS
AND THUNDERSTORMS. INSTABILITY IS PREVALENT BUT SHEAR IS ON THE
WEAKER SIDE AS OF NOW BUT DEPENDING ON THE SHEAR AXIS ORIENTATION
TO THE STORMS, WE COULD SEE CELL MERGER OCCUR FORMING A BROKEN
LINE OF STORMS WITH STRONGER WINDS THE MAIN ISSUE. PWATS APPROACH
AND COULD SURPASS 2" SO HEAVY EFFICIENT RAINERS IS ALSO LIKELY
WITH POOR DRAINAGE AND SPOTTY FLASH FLOOD ISSUES POSSIBLE.

FRIDAY - SUNDAY...AS MID-LEVEL TROUGHING BEGINS TO STRENGTHEN BY THE
WEEKEND, THE AFOREMENTIONED FRONT BECOMES MORE PARALLEL TO THE UPPER-
LEVEL FLOW...IT LOOKS TO STALL OFFSHORE. IT BEGINS TO SLOW ITS
DEPARTURE EARLY ON FRIDAY SO THERE COULD BE SOME LINGERING SHOWERS
AND THUNDERSTORMS FRIDAY MORNING BEFORE DRYING OUT. TEMPERATURES
WILL STILL BE QUITE WARM BUT THE FRONT SHOULD BE ABLE TO EAT UP THE
HIGHER DEWPOINTS AS THE AIRMASS DRIES OUT A BIT. WE LOOK TO BE ON
THE SOUTHERN EXTENT OF THE TROUGHING SO MOST OF THE MID-LEVEL ENERGY
STAYS TO OUR NORTH THROUGH THE WEEKEND KEEPING US MOSTLY DRY...COULD
BE SOME ISOLATED SHOWERS ACROSS SOUTHERN DELMARVA CLOSER TO THE
STALLED BOUNDARY. TEMPERATURES ON SATURDAY AND SUNDAY WILL STILL
REMAIN 90+ DEGREES.

MONDAY -  TUESDAY...ANOTHER COLD FRONT IS PROGGED TO PUSH CLOSER TO
THE REGION BY LATE MONDAY INTO TUESDAY. TEMPERATURES AHEAD OF THE
FRONT WILL ONCE AGAIN BE 90+ DEGREES WITH A MOISTENING AIRMASS.
MORE SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE.

&&

.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

AN AREA OF SHOWERS AND NEARBY STORMS CURRENTLY IMPACTING ACY WITH
A BRIEF PERIOD OF IFR VSBYS. OTHERWISE, VCSH MENTIONED AT ILG AND
MIV THRU 00Z.

A MAINLY CLEAR SKY IS EXPECTED FOR TONIGHT. WHILE SCATTERED LOW
CLOUDS, HAZE AND LIGHT FOG REMAIN POSSIBLE FOR LATE TONIGHT AND
EARLY WEDNESDAY MORNING, IT SHOULD NOT BE NEARLY AS WIDESPREAD AS IT
WAS THIS MORNING.

VFR CONDITIONS WITH SCATTERED CUMULUS IS IN THE FORECAST FOR
WEDNESDAY. THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IS VERY LOW.

A LIGHT SOUTHWEST TO SOUTH WIND, GENERALLY LESS THAN 10 KNOTS, IS
EXPECTED THROUGH THE TAF PERIOD.

OUTLOOK...
THURSDAY...EARLY MORNING FOG/HAZE WITH MVFR CONDITIONS POSSIBLE...THEN
SCT AFTERNOON/EVENING TSTMS WITH MVFR OR LOWER CONDS.

FRIDAY - SUNDAY...VFR.

&&

.MARINE...
WEAK HIGH PRESSURE WILL CONTINUE TO AFFECT THE COASTAL WATERS OF NEW
JERSEY AND DELAWARE FOR TONIGHT AND WEDNESDAY.

A SOUTHWEST TO SOUTH WIND AROUND 5 TO 10 KNOTS IS EXPECTED. WAVE
HEIGHTS ON THE OCEAN WILL FAVOR 2 TO 3 FEET WHILE WAVES ON DELAWARE
BAY SHOULD BE 2 FEET OR LESS.

OUTLOOK...
THURSDAY - SUNDAY...SUB-SCA CONDITIONS EXPECTED THIS PERIOD.
THUNDERSTORM CHANCES INCREASE ON THURSDAY WITH VERY HEAVY RAINFALL
AND STRONG WIND GUSTS POSSIBLE.

&&

.RIP CURRENTS...
THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS RIP
CURRENTS ALONG THE NEW JERSEY AND DELAWARE COAST INTO THIS EVENING
DUE TO A LONG PERIOD SOUTHEASTERLY SWELL. THE WAVE PERIOD WILL
CONTINUE TO BE AROUND 10 SECONDS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...IOVINO/KLEIN
SHORT TERM...IOVINO
LONG TERM...HEAVENER
AVIATION...IOVINO/HEAVENER/KLEIN
MARINE...IOVINO/HEAVENER
RIP CURRENTS...


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