Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 280726
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
326 AM EDT TUE JUL 28 2015

.SYNOPSIS...
WEAK HIGH PRESSURE BUILDING EASTWARD FROM THE GREAT LAKES IS
FORECAST TO INFLUENCE OUR WEATHER TODAY THROUGH WEDNESDAY. A FRONTAL
BOUNDARY FROM THE NORTHWEST IS EXPECTED TO ARRIVE THURSDAY NIGHT,
FOLLOWED BY HIGH PRESSURE FOR FRIDAY AND THE WEEKEND. ANOTHER FRONT
MAY APPROACH FROM THE NORTHWEST ON MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH AXIS NOW TO
OUR EAST WITH A RIDGE BUILDING TO OUR WEST. THIS ALLOWS A
NORTHWESTERLY FLOW ALOFT REGIME TO BE MAINTAINED ACROSS THE
NORTHEAST AND MID ATLANTIC. AT THE SURFACE, WEAK HIGH PRESSURE IS
FORECAST TO SETTLE INTO OUR AREA TODAY.

AS THE RIDGE TO OUR WEST GRADUALLY BUILDS NORTH AND EASTWARD SOME
THROUGH TODAY, THERE DOES NOT APPEAR TO BE MUCH IN THE WAY OF SHORT
WAVE ENERGY /AT LEAST ORGANIZED/ SLIDING SOUTHEASTWARD. AS A RESULT,
NO ORGANIZED AREAS OF LIFT IS FORECAST TO OCCUR TODAY WITHIN A VERY
WARM TO HOT AND HUMID AIR MASS. THE FORECAST SOUNDINGS DO SHOW
DECENT INSTABILITY DEVELOPING THROUGH THE AFTERNOON, HOWEVER ABOVE
ABOUT THE 850 MB LEVEL IT IS DRY. THE WATER VAPOR IMAGERY EARLY THIS
MORNING SHOWS A LOT OF MID LEVEL DRY AIR FROM AROUND THE EASTERN
GREAT LAKES TO THE MID ATLANTIC. AS A RESULT, ANY CONVECTION THAT
CAN DEVELOP SHOULD BE ISOLATED AND ALSO PULSE DRIVEN GIVEN LITTLE
FLOW IN THE LOWER TO MID LEVELS. IT APPEARS THAT SEA AND BAY BREEZE
BOUNDARIES ESPECIALLY THIS AFTERNOON COULD FOCUS SOME CONVECTIVE
DEVELOPMENT AND WE CONTINUED WITH SLIGHT CHC POPS FOR THE EASTERN
ZONES AND PORTIONS OF THE DELMARVA. ELSEWHERE, WE OPTED TO CARRY A
DRY FORECAST ATTM AS THERE IS NOT MUCH TO LATCH ONTO FOR CONVECTIVE
INITIATION OTHER THAN TERRAIN. SOME WARMING AROUND THE 925 MB LEVEL
MAY ALSO TEMPER CONVECTIVE DEVELOPMENT.

A POCKET OF NEAR +25C AIR AT 925 MB IS FORECAST TO ADVECT INTO OUR
AREA THROUGH THE AFTERNOON. DESPITE SOME CUMULUS DEVELOPMENT, PLENTY
OF HEATING IS EXPECTED /ALTHOUGH A LACK OF MIXING DUE TO THE WEAK
FLOW/ AND THEREFORE SOME AREAS ARE ANTICIPATED TO REACH 90 DEGREES
THIS AFTERNOON. THE STRONG WARMING OF THE BOUNDARY LAYER MAY ALLOW
THE SURFACE DEW POINTS TO DECREASE AT LEAST SOME ESPECIALLY FARTHER
NORTH ACROSS THE CWA, AND WITH WEAK FLOW SEA AND BAY BREEZES ARE
EXPECTED. THIS WILL PROVIDE SOME COOLING ALONG THE COAST.

AS FOR THE HIGH TEMPERATURES, WE USED AN EVEN BLEND OF THE NAM/GFS
MOS THEN MADE SOME LOCAL TWEAKS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
A WEAK SURFACE HIGH IS FORECAST TO BE OVER OUR AREA TONIGHT AS AN
UPPER-LEVEL RIDGE AXIS SLIDES ACROSS THE EASTERN GREAT LAKES AND
OHIO VALLEY. THIS STILL MAINTAINS NORTHWESTERLY FLOW ALOFT, BUT
LIGHT AND VARIABLE FLOW AT THE SURFACE. DUE TO A LACK OF ORGANIZED
SHORT WAVES TO PROVIDE ENOUGH LIFT, AN ISOLATED SHOWER OR
THUNDERSTORM INITIATED PROBABLY BY ANY LOW-LEVEL CONVERGENCE /I.E.
SEA AND BAY BREEZES/ ARE EXPECTED TO DISSIPATE EARLY IN THE EVENING.
IN ADDITION, ANY CUMULUS FIELD IS EXPECTED TO FLATTEN AND DISSIPATE
WITH PERHAPS SOME HIGH CLOUDINESS OCCURRING AT TIMES.

IT WILL BE A WARM AND MUGGY NIGHT FOR MUCH OF THE CWA AS THE SURFACE
DEW POINTS SHOULD RECOVER FROM ANY DAYTIME HEATING INFLUENCE. THE
COMBINATION OF LIGHT TO CALM WINDS, A MOIST BOUNDARY LAYER AND NOT A
LOT OF CLOUDINESS COULD RESULT IN PATCHY LOW CLOUDS/FOG DEVELOPMENT
LATE.

AS FOR THE LOW TEMPERATURES, A MOS BLEND WAS GENERALLY USED.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
A MID LEVEL RIDGE IS EXPECTED TO PROGRESS EASTWARD AND ITS AXIS
SHOULD PASS OVER OUR REGION ON WEDNESDAY NIGHT. A MID LEVEL LOW IS
ANTICIPATED TO MOVE TO HUDSON BAY ON WEDNESDAY NIGHT. THE LOW IS
FORECAST TO MEANDER OVER THE HUDSON BAY REGION FROM WEDNESDAY
NIGHT THROUGH MONDAY. MID LEVEL TROUGHING IS EXPECTED OVER THE
NORTHEASTERN STATES FOR THURSDAY NIGHT THROUGH MONDAY WITH A RIDGE
BUILDING OVER THE WESTERN STATES.

THE HEAT IS FORECAST TO BE ON THE INCREASE FOR WEDNESDAY AND
THURSDAY. WE ARE ANTICIPATING MAXIMUM TEMPERATURES MAINLY IN THE
LOWER AND MIDDLE 90S ON BOTH DAYS WITH HEAT INDEX VALUES
APPROACHING 100 EXCEPT IN THE ELEVATED TERRAIN AND IN THE
COMMUNITIES ALONG THE COAST. DEW POINT READINGS ARE EXPECTED TO BE
MAINLY IN THE MID TO UPPER 60S ON WEDNESDAY AFTERNOON AND IN THE
UPPER 60S AND LOWER 70S ON THURSDAY AFTERNOON.

THE MAXIMUM HEAT INDEX VALUES IN OUR HIGHLY URBANIZED AREAS ALONG
THE INTERSTATE 95 CORRIDOR ARE EXPECTED TO BE IN THE UPPER 90S ON
WEDNESDAY AND THURSDAY BASED ON THE LATEST GUIDANCE. AS A RESULT,
WE WILL NOT ISSUE AN EXCESSIVE HEAT WATCH AT THIS TIME. THE
GUIDELINE CRITERION IS 100. HOWEVER, WE WILL KEEP A CLOSE WATCH TO
SEE IF THE GUIDANCE BEGINS TO CREEP UPWARD WITH EITHER THE
TEMPERATURE OR DEW POINT FORECAST.

WE ARE NOT ANTICIPATING ANY PRECIPITATION FOR TUESDAY NIGHT,
WEDNESDAY AND WEDNESDAY NIGHT DUE TO THE LACK OF ANY SUBSTANTIAL
TRIGGERING MECHANISMS. WE WILL MENTION A CHANCE OF SHOWERS AND
THUNDERSTORMS FOR THURSDAY AFTERNOON INTO THURSDAY NIGHT AS A
FRONTAL BOUNDARY IS EXPECTED TO APPROACH AND PASS THROUGH OUR
REGION DURING THAT PERIOD OF TIME. A WEAK WAVE OF LOW PRESSURE MAY
DEVELOP ALONG THE FRONT CAUSING PRECIPITATION TO LINGER INTO EARLY
FRIDAY MORNING IN OUR SOUTHEASTERN COUNTIES.

HIGH PRESSURE IS EXPECTED TO FOLLOW THURSDAY NIGHT`S FRONTAL
PASSAGE. THE HIGH IS ANTICIPATED TO INFLUENCE OUR WEATHER FOR
FRIDAY AND THE WEEKEND. WE WILL CARRY A PRECIPITATION-FREE
FORECAST ALONG WITH SLIGHTLY ABOVE NORMAL DAYTIME TEMPERATURES.
EVEN WITH THE MID LEVEL TROUGHING, IT APPEARS AS THOUGH OUR
WEATHER WILL REMAIN QUITE WARM. HOWEVER, HUMIDITY LEVEL SHOULD
DROP A BIT FROM THOSE EXPECTED DURING THE MID WEEK PERIOD.

ANOTHER FRONTAL BOUNDARY MAY APPROACH FROM THE NORTHWEST ON
MONDAY AND WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS
FOR THAT PERIOD OF TIME.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TODAY...LOCAL LOW CLOUDS/FOG DISSIPATE BY MID MORNING, OTHERWISE
VFR WITH A CLOUD BASE MOSTLY BETWEEN 3500-5000 FEET. AN ISOLATED
SHOWER OR THUNDERSTORM MAY DEVELOP THROUGH THE DAY ESPECIALLY
SOUTH AND EAST OF KPHL. SEA/BAY BREEZES ARE EXPECTED TO DEVELOP BY
MID AFTERNOON AND AFFECT KACY, KMIV AND KILG WITH WINDS TURNING
MORE FROM THE SOUTHEAST.

TONIGHT...MAINLY VFR. HOWEVER DUE TO THE MOIST AIR MASS IN PLACE,
SOME LATE NIGHT LOW CLOUDS/FOG MAY DEVELOP, AND OUR CONFIDENCE IS
ON THE LOWER SIDE AT THIS TIME. LIGHT SOUTHERLY TO CALM WINDS.

OUTLOOK...
WEDNESDAY THROUGH THURSDAY MORNING...MAINLY VFR. HOWEVER, THE
HIGH HUMIDITY LEVELS MAY RESULT IN SOME LATE NIGHT AND EARLY
MORNING LOW CLOUDS, HAZE AND FOG.

THURSDAY AFTERNOON AND THURSDAY NIGHT...A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT MAY RESULT IN MVFR OR IFR CONDITIONS AT TIMES.

FRIDAY THROUGH SATURDAY...MAINLY VFR.

&&

.MARINE...
THE CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA THROUGH TONIGHT. A SOUTHERLY FLOW WILL CONTINUE WITH SOME
ENHANCEMENT OCCURRING THIS AFTERNOON AND EARLY EVENING AS A SEA AND
BAY BREEZE DEVELOPS. THE SEAS SHOULD RUN IN THE 1-3 FEET RANGE
THROUGH TONIGHT.

OUTLOOK...
WEDNESDAY THROUGH SATURDAY...NO MARINE HEADLINES ARE ANTICIPATED.

&&

.RIP CURRENTS...
A LONG PERIOD /AROUND 10 SECONDS/ SWELL FROM THE EAST-SOUTHEAST WILL
CONTINUE TODAY. A SOUTHERLY WIND AT 10-15 MPH WITH SOME AFTERNOON
SEA BREEZE ENHANCEMENT ALONG WITH WAVES OF AROUND 2 FEET IN THE SURF
ZONE ARE FORECAST TODAY. THE SETUP IS SIMILAR TO YESTERDAY AND
THEREFORE WE WILL MAINTAIN A MODERATE RISK OF DANGEROUS RIP CURRENTS
FOR BOTH THE NEW JERSEY AND DELAWARE COASTS.

&&

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

&&

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



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