Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 271510
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1110 AM EDT SAT JUN 27 2015

.SYNOPSIS...
LOW PRESSURE WILL TRACK ACROSS OHIO TO WESTERN PENNSYLVANIA TODAY
INTO TONIGHT, THEN INTO NEW ENGLAND BY LATE SUNDAY. A WEAK AREA OF
HIGH PRESSURE WILL BUILD IN FOR MONDAY, THEN A COLD FRONT SETTLES
ACROSS OUR REGION LATER TUESDAY AND WEDNESDAY BEFORE STALLING TO
OUR SOUTH THURSDAY. THIS FRONT MAY THEN LIFT NORTHWARD ACROSS OUR
AREA FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WE HAVE NOT NEEDED MAY CHANGES DURING THE MID-MORNING UPDATE.
THERE WERE SOME MINOR POP CHANGES FOR THE ONSET OF THE STEADIER
RAINS. A COUPLE OF MAX TEMPS CHANGES WERE ALSO MADE ACROSS THE
NORTH. THE PREVIOUS DESCRIPTION OF THE OVERALL SITUATION REMAINS
VALID AND IS COPED BELOW.

A MID LEVEL LOW IS FORECAST TO DRIFT ACROSS SOUTHERN MICHIGAN
TODAY. MEANWHILE, A SURFACE REFLECTION OF THE LOW IS EXPECTED TO
PASS ACROSS OHIO. THE SURFACE LOW IS ANTICIPATED TO LIFT A WARM
FRONT TOWARD OUR REGION TODAY. AN EAST TO SOUTHEAST SURFACE FLOW
IS EXPECTED AND THAT FLOW WILL DRAW ATLANTIC MOISTURE INTO OUR
REGION.

A LARGE AREA OF RAIN ASSOCIATED WITH THE LOW TO OUR WEST WILL
SPREAD INTO OUR REGION THIS MORNING. RAINFALL RATES WILL BECOME
ENHANCED THIS AFTERNOON DUE TO THE INCREASING ISENTROPIC LIFT, A
DEVELOPING SOUTHEAST TO SOUTH LOW LEVEL JET AND INCREASING
MOISTURE. WE WILL LEAVE THE FLOOD WATCH IN PLACE FOR SOUTHEASTERN
PENNSYLVANIA (INCLUDING BERKS COUNTY AND THE LEHIGH VALLEY) AND
FOR CECIL COUNTY IN MARYLAND AND NEW CASTLE COUNTY IN DELAWARE.

A FAIR AMOUNT OF WIND SHEAR ALONG WITH MARGINAL INSTABILITY WILL
CREATE THE POTENTIAL FOR LOW TOPPED SEVERE THUNDERSTORMS MAINLY IN
AREAS NEAR THE APPROACHING WARM FRONT. THE AREA OF GREATEST
CONCERN INCLUDES NORTHEASTERN MARYLAND, DELAWARE AND THE ADJACENT
COUNTIES OF SOUTHEASTERN PENNSYLVANIA AND SOUTHERN NEW JERSEY. THE
GREATEST THREAT IS FROM THIS AFTERNOON INTO THIS EVENING.

HIGH TEMPERATURES ARE FORECAST TO RANGE FROM THE 60S TODAY IN OUR
NORTHERN COUNTIES TO THE LOWER 80S IN THE SOUTH.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE MID LEVEL LOW IS FORECAST TO MOVE ALONG LAKE ERIE TONIGHT
WITH THE SURFACE LOW EXPECTED TO BE IN THAT VICINITY, AS WELL. A
SECONDARY LOW IS ANTICIPATED TO DEVELOP AT THE TRIPLE POINT AROUND
THE WASHINGTON AND BALTIMORE AREA THIS EVENING BEFORE LIFTING
NORTHEASTWARD AND INTO OUR FORECAST AREA OVERNIGHT.

A SOUTHERLY LOW LEVEL JET WILL CONTINUE TO DRAW MOISTURE INTO OUR
REGION TONIGHT. PRECIPITABLE WATER VALUES SHOULD EXCEED 2 INCHES
IN MUCH OF OUR REGION. RAIN IS ANTICIPATED FOR MUCH OF THE NIGHT
AND IT SHOULD TAPER TO SHOWERS WITH THE ARRIVAL OF THE LOW.

RAINFALL TOTALS FOR THE EVENT ARE EXPECTED TO RANGE MAINLY FROM
1.5 TO 2.5 INCHES FROM THE INTERSTATE 95 CORRIDOR NORTHWESTWARD.
LOCALLY HIGHER AMOUNTS ARE LIKELY. RAINFALL AMOUNTS NEAR THE COAST
SHOULD RANGE FROM ABOUT AN INCH TO AN INCH AND A QUARTER.

THE EAST TO SOUTHEAST SURFACE FLOW IS FORECAST TO LESSEN TONIGHT
BEFORE BECOMING SOUTHWEST AFTER THE LOW PASSES. MINIMUM
TEMPERATURES SHOULD BE MAINLY IN THE 60S.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE SYNOPTIC SETUP IS COMPRISED OF A RIDGE ACROSS THE WEST WITH A
TROUGH ACROSS THE EAST. THIS WILL RESULT IN SOME UNSETTLED WEATHER
AT TIMES ESPECIALLY AS IT AMPLIFIES AND TOSSES SOME FRONTAL
BOUNDARIES OUR WAY, HOWEVER EVEN A SURGE IN WARMTH IS ANTICIPATED
FOR A TIME. WE USED A MODEL BLEND FOR SUNDAY THROUGH TUESDAY, THEN
BLENDED IN THE 00Z WPC GUIDANCE WITH CONTINUITY. SOME ADJUSTMENTS
WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR
NEIGHBORING OFFICES.

FOR SUNDAY...SHOWERS ARE EXPECTED TO QUICKLY END EARLY IN THE
MORNING FROM SOUTHWEST TO NORTHEAST AS LOW PRESSURE HEADS TOWARD
NEW ENGLAND. THERE THEN SHOULD BE A FEW LINGERING WRAPAROUND
SHOWERS THROUGH THE DAY MAINLY UP NORTH. OTHERWISE, SOME SUNSHINE
SHOULD DEVELOP DURING THE DAY ESPECIALLY SOUTH AS LOW PRESSURE
MOVES TO OUR NORTH AND NORTHEAST AND WINDS SHIFT TO SOUTHWEST AND
WEST. THE PRESSURE GRADIENT TIGHTENS AND WITH BOUNDARY LAYER
HEATING AND DEEPER MIXING BREEZY CONDITIONS SHOULD OCCUR DURING
THE DAY FOR MUCH OF THE CWA, THEN THE WINDS START TO DIMINISH AT
NIGHT.

FOR MONDAY AND TUESDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
REMAIN IN PLACE DURING THIS TIME FRAME, WITH EVEN SOME
AMPLIFICATION TAKING PLACE TUESDAY. A WEAK AREA OF HIGH PRESSURE
SHOULD BUILD IN FOR MONDAY, HOWEVER THE NEXT SHORT WAVE TO AMPLIFY
THE TROUGH SWINGS ACROSS THE LOWER GREAT LAKES MONDAY NIGHT AND
TUESDAY. THIS MAY ALLOW FOR A WEAK WARM FRONT TO LIFT NORTHWARD
TUESDAY WITH POTENTIALLY SOME SURGE IN WARMTH. AN INCREASE IN WAA
AND LIFT SHOULD RESULT IN SOME CONVECTION ESPECIALLY INLAND
TUESDAY.

FOR WEDNESDAY THROUGH FRIDAY...A STRONGER PUSH OF THE UPPER-
LEVEL TROUGH IS FORECAST TO OCCUR DURING THIS TIME FRAME. THIS
SHOULD FORCE A COLD FRONT ACROSS OUR AREA WEDNESDAY BEFORE
STALLING TO OUR SOUTH THURSDAY. THIS COULD RESULT IN SOME SHOWERS
AND THUNDERSTORMS ON WEDNESDAY. THERE IS THE POTENTIAL FOR SHORT
WAVE ENERGY TO RIDE THE TAIL END OF THE FRONT, AND THEREFORE
SLOWING THE FRONT DOWN AS IT CROSSES OUR AREA. AS OF NOW, WE STALL
THE FRONT TO OUR SOUTH THURSDAY THEN AS ANOTHER TROUGH AMPLIFIES
FROM THE WEST THE FRONT SHOULD LIFT NORTHWARD FRIDAY. AT LEAST
SOME OF THE MODEL GUIDANCE MAY HAVE CONVECTIVE FEEDBACK ISSUES,
HOWEVER THE PATTERN LOOKS ACTIVE WITH POTENTIAL ENERGY SLIDING
EAST WITH A FRONT LIFTING NORTH. OVERALL, THE POPS ARE IN THE CHC
RANGE OR LESS.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY, AND SURROUNDING AREAS.

VFR CONDITIONS CONTINUE AT THE TAF SITES THIS MORNING...BUT A
TREND TOWARD MVFR CONDITIONS WILL CONTINUE...BEGINNING N/W DURING
THE EARLY AFTERNOON. CONDITIONS WILL CONTINUE TO DETERIORATE
GRADUALLY...AND WE ARE ANTICIPATING MVFR AND IFR CONDITIONS FOR
MUCH OF THE LATE AFTERNOON INTO TONIGHT. THE RAIN WILL BECOME
MODERATE TO HEAVY AT TIMES AND SCATTERED THUNDERSTORMS ARE
ANTICIPATED.

AN EAST TO SOUTHEAST WIND IS FORECAST TO INCREASE TO 10 TO 15
KNOTS FOR TODAY WITH GUSTS IN THE 20 TO 25 KNOT RANGE. THE EAST TO
SOUTHEAST WIND WILL CONTINUE INTO THIS EVENING BEFORE DECREASING
AND GRADUALLY BECOMING SOUTHWEST LATE TONIGHT.

OUTLOOK...
SUNDAY...WIDESPREAD SHOWERS SHIFTING TO OUR NORTHEAST EARLY, THEN
A FEW SHOWERS DURING THE DAY MAINLY NORTH AND WEST OF KPHL. THE
CONDITIONS ARE EXPECTED TO BE VFR OVERALL. SOUTHWEST TO WEST WINDS
12 TO 15 KNOTS WITH GUSTS TO 25 KNOTS, DIMINISHING SOME AT NIGHT.

MONDAY...VFR. WESTERLY WINDS 5 TO 10 KNOTS.

TUESDAY...MAINLY VFR, HOWEVER SUB-VFR POSSIBLE IN ANY SHOWERS OR
THUNDERSTORMS THAT MAY DEVELOP. SOUTHERLY WINDS 10 TO 15 KNOTS.

WEDNESDAY...SUB-VFR POSSIBLE IN SHOWERS OR THUNDERSTORMS.
WESTERLY WINDS 5 TO 10 KNOTS.

&&

.MARINE...
LOW PRESSURE WILL CONTINUE TO APPROACH FROM THE WEST DURING TODAY
AND TONIGHT. AN EAST TO SOUTHEAST WIND IS FORECAST TO INCREASE TO
15 TO 25 KNOTS FOR TODAY INTO THIS EVENING. GUSTS AROUND 30 KNOTS
ARE ANTICIPATED. WAVE HEIGHTS ON OUR OCEAN WATERS ARE EXPECTED TO
BUILD TO 6 TO 8 FEET.

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR OUR OCEAN WATERS FOR
TODAY AND TONIGHT. THE ADVISORY IS IN EFFECT ONLY UNTIL 1100 PM
FOR DELAWARE BAY. WIND SPEEDS ARE ANTICIPATED TO DECREASE
GRADUALLY TONIGHT BUT WAVE HEIGHTS SHOULD REMAIN ABOVE 5 FEET ON
OUR OCEAN WATERS.

OUTLOOK...
SUNDAY...THE SMALL CRAFT ADVISORY IN EFFECT DURING THE DAY BUT
MAY NEED TO BE EXTENDED INTO THE EVENING. IN ADDITION, WINDS MAY
GUST TO 25 KNOTS ON DELAWARE BAY AND THEREFORE AN ADVISORY MAY
NEED TO BE ADDED. SEAS REMAINING ELEVATED BUT GRADUALLY SUBSIDING
THROUGH THE EVENING.

MONDAY...THE WINDS AND SEAS ARE ANTICIPATED TO SUBSIDE BELOW
ADVISORY CRITERIA.

TUESDAY...AN INCREASE IN A SOUTHERLY FLOW MAY BUILD THE SEAS ON
THE OCEAN TO ADVISORY CRITERIA.

WEDNESDAY...SUBSIDING SEAS WITH SUB-ADVISORY CONDITIONS
ANTICIPATED.

&&

.HYDROLOGY...
A FLOOD WATCH IS IN EFFECT FOR BERKS COUNTY, THE LEHIGH VALLEY
AND SOUTHEASTERN PENNSYLVANIA FROM NOON TODAY UNTIL 500 AM SUNDAY.
ALSO, THE FLOOD WATCH INCLUDES CECIL COUNTY IN MARYLAND AND NEW
CASTLE COUNTY IN DELAWARE.

WE ARE ANTICIPATING WIDESPREAD RAINFALL AMOUNTS OF 1.5 TO 2.5
INCHES IN THE WATCH AREA. LOCALLY HIGHER AMOUNTS ARE LIKELY. THE
LOWER SCHUYLKILL RIVER VALLEY IS PARTICULARLY VULNERABLE TO NEW
FLOODING DUE TO THE SATURATED CONDITIONS THERE. RADAR INDICATED
LOCALIZED RAINFALL AMOUNTS OF GREATER THAN 4 INCHES FROM AROUND
PHOENIXVILLE AND COLLEGEVILLE DOWN TO CONSHOHOCKEN DURING THE
HOURS AROUND MIDNIGHT.

GENERALLY, SMALL STREAMS AND CREEKS WILL BE MOST VULNERABLE
DURING THIS EVENT ALONG WITH AREAS OF POOR DRAINAGE. THE MAIN
RIVERS SUCH AS THE LEHIGH, THE SCHUYLKILL AND THE DELAWARE ARE NOT
EXPECTED TO FLOOD.

&&

.TIDES/COASTAL FLOODING...
THE EAST TO SOUTHEAST FLOW WILL PUSH WATER UP ALONG THE COAST AND
INTO DELAWARE BAY. WE ARE NOT ANTICIPATING ANY PROBLEMS ON THE
OCEANFRONT OR ALONG THE DELAWARE BAY SHORE. HOWEVER, WE ARE A BIT
CONCERNED THAT MINOR TIDAL FLOODING MAY OCCUR EARLY TONIGHT ON THE
LOWER DELAWARE RIVER AS THE SURGE WORKS ITS WAY INTO THAT AREA.
HIGH TIDE AT REEDY POINT, DELAWARE IS AT 838 PM AND HIGH TIDE AT
PHILADELPHIA OCCURS AT 1113 PM.

WE WILL RE-EXAMINE THE LATEST GUIDANCE AND A COASTAL FLOOD
ADVISORY MAY BE NEEDED FOR THE LOWER DELAWARE RIVER FOR EARLY
TONIGHT.

&&

.RIP CURRENTS...
THE STRENGTHENING EAST TO SOUTHEAST FLOW WILL RESULT IN THE
DEVELOPMENT OF A HIGH RISK OF RIP CURRENTS TODAY ALONG THE NEW
JERSEY SHORE. WE WILL KEEP THE RISK AT MODERATE FOR THE DELAWARE
BEACHES BASED ON OUTPUT FROM OUR LOCAL PROGRAM.

THE SURF IS EXPECTED TO BECOME DANGEROUS TODAY. BE SAFE AND STAY
OUT OF THE WATER.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH THROUGH LATE TONIGHT FOR PAZ060>062-070-071-
     101>106.
NJ...HIGH RIP CURRENT RISK UNTIL 10 PM EDT THIS EVENING FOR NJZ014-
     024>026.
DE...FLOOD WATCH THROUGH LATE TONIGHT FOR DEZ001.
MD...FLOOD WATCH THROUGH LATE TONIGHT FOR MDZ008.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ430-
     431.

&&

$$
SYNOPSIS...GORSE
NEAR TERM...IOVINO/PO
SHORT TERM...IOVINO
LONG TERM...GORSE
AVIATION...GORSE/IOVINO/MEOLA/PO
MARINE...GORSE/IOVINO/MEOLA
HYDROLOGY...
TIDES/COASTAL FLOODING...
RIP CURRENTS...



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