Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 070905
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
505 AM EDT TUE JUL 7 2015

.SYNOPSIS...
A TROUGH OF LOW PRESSURE LOCATED TO OUR SOUTH TODAY WILL MERGE WITH
A COLD FRONTAL BOUNDARY APPROACHING THE REGION TONIGHT. THIS FRONTAL
BOUNDARY WILL VERY SLOWLY MOVE THROUGH THE REGION BY FRIDAY,
BECOMING NEARLY STATIONARY. SEVERAL WAVES OF LOW PRESSURE WILL ALSO
TRAVEL EASTWARD ALONG THE BOUNDARY. A WARM FRONTAL BOUNDARY WILL
THEN LIFT NORTHEASTWARD THROUGH THE REGION NEXT WEEKEND GIVING WAY
TO ANOTHER COLD FRONTAL BOUNDARY BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY TODAY...STRATUS AND A COUPLE OF DYING ISOLATED LEFTOVER SHOWERS
FROM THIS PAST EVENINGS REMNANT HEAVY SHOWERS/TSTMS ON THE DELMARVA/E
PA. PWAT RIGHT NOW STILL NEAR 1.9 INCHES BUT SLOWLY LOWERS FROM SW
TO NE DURING THE DAY, DOWN TO NEAR 1.6 INCHES LATE AFTN.

DENSE FOG RELEGATED TO THE RIDGES, IF THAT.

THE OVERALL TREND HERE AT 445 AM IS FOR IMPROVING CIGS.

UNSTABLE THIS AFTN IN THE WARM SECTOR AND MODELS CONTINUE DEVELOPING
CLUSTERS OF HEAVY SHOWERS AND ISOLATED GULLY WASHING THUNDERSTORMS
AS THE WEAKENING CLOSED LOW SHORT WAVE LIFTS NEWD OVERHEAD THIS
AFTERNOON.

BULK SHEAR IS MINIMAL TODAY SO ANY TSTORM GUSTS SHOULD NOT EXCEED
40 KT.

BLENDED 00Z/7 GFS/NAM POPS WERE USED WITH SOME SREF/HRRR DIURNAL
DRIER MORNING MODIFICATION OF THE POPS. IN ESSENCE THE SHOWERS
TODAY, MAINLY ALONG AND NW OF I-95, ESP E PA AND NORTHERN NJ (N
OF I-78).

OTHERWISE...THE STRATUS BURNS OFF RAPIDLY FROM SW TO NE DURING MID
MORNING WITH A BKN DECK NEAR 5000 FT EARLY THIS AFTN AND THAT TOO
DRYING OUT FROM SW TO NE DURING MID-LATE AFTN.

HEAT FOLLOWS THIS AFTN WITH 90-92F EXPECTED TO BE WIDESPREAD ON A
GUSTY SW WIND TO 20 MPH. THE HEAT INDEX WITH DEWPOINTS DIPPING
BACK TO THE UPPER 60S SHOULD BE IN THE 95-99 CATEGORY FOR A FEW
HOURS BUT NO HEAT ADVISORY. BLENDED THE 00Z/7 GFS/NAM MOS GUIDANCE
AND MODIFIED IT UP A DEGREE FOR THE 16-17C 850 TEMPS.

THE PRIMARY HAZARD TODAY WILL LIKELY BE POOR DRAINAGE ROAD FLASH
FLOOD OPPORTUNITIES WHERE CONVECTION TRAINS FOR AN HOUR OR SO.
HOURLY FFG IN MORRIS COUNTY IS OUR MOST VULNERABLE AREA WITH ONLY 1
INCH NEEDED IN AN HOUR IN PARTS OF MORRIS COUNTY. SUSPECT WE`LL
SEE SOME CONVECTIVE NARROW SWATH FFW`S THIS AFTN ALONG AND N OF
I-78. THE IDEA: IF WARNINGS ARE ISSUED FOR YOUR AREA, NO WORKING
IN CULVERTS OR PLAYING ALONG SIDE SMALL STREAMS.

IF HEAVY SHOWERS HAVEN`T DEVELOPED BY 4PM, ITS UNLIKELY THEREAFTER
IN OUR AREA AS THE BACK EDGE OF THE DEEPER INSTABILITY (KI=30) IS
DEPARTING NEWD FROM NE NJ. THEREFORE, LOWERED POPS TO NO MENTION
AT 6 PM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
RAINFREE THIS EVENING AND QUITE WARM! THEN A BAND OF CONVECTION
AHEAD OF THE EWD MOVING COLD FRONT MAY ARRIVE AND CROSS NE PA AND
NW NJ NEAR AND AFTER MIDNIGHT WITH ISOLATED EMBEDDED THUNDER. PWAT
IN THE EARLY EVENING BRIEFLY DRIES TO 1.4 INCHES BUT WITH THE
CONVECTIVE BAND, INCREASES TO 1.85 INCHES BY WEDNESDAY MORNING.

OTHERWISE...I CALL IT SUMMERTIME FAIR-A TYPICAL WARM SUMMER NIGHT!

USED THE WARMER OF THE AVAILABLE MOS GUIDANCE FOR TONIGHT.

LIGHT SW WIND.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
WEDNESDAY AND WEDNESDAY NIGHT: A COLD FRONTAL BOUNDARY BEGINS TO
ENTER THE PICTURE WEDNESDAY AFTERNOON AND EVENING GIVING US THE
TRIGGER MISSING TODAY FOR A MORE WIDESPREAD SHOWER AND THUNDERSTORM
CHANCE. WITH THE HIGHER CHANCES OF RAIN, HIGH TEMPERATURES MAY NOT
REACH THE FULL POTENTIAL DUE TO THE PRESENCE OF MORE CLOUDS. DID
KNOCK DOWN THE HIGHS BUT NOT AS MUCH AS MET/ MAT ECMWF MOS DO, GIVEN
THE MAJORITY OF PRECIPITATION HOLDS OFF TILL AFTER 18Z. PLENTY OF
WINDOW FOR WARMING AHEAD OF THE FRONT. ANOTHER RESULT OF THE
PROSPECTS FOR INCREASED CLOUD COVER IS THAT MODELED INSTABILITY
HAS DECREASED TO UNDER 1000 J/KG OF CAPE IN SOME PARTS OF THE
REGION COUPLED WITH LESS IN THE WAY OF MODELED STEEP LAPSE RATES.
SHEAR CONTINUES TO LOOK TO BE MINIMAL AS WELL IN THE REGION. THIS
POINTS TO ANY STRONG/SEVERE STORM TO BE ISOLATED. HEAVY RAIN LOOKS
TO BE THE PRIMARY CONCERN WITH PW VALUES NEAR 2 INCHES. STORM
MOTIONS LOOK FASTER AS WELL, SO EVEN WITH THE INCREASED
CONVERGE ANY OCCURRENCES OF FLASH FLOODING MAY NOT BE WIDESPREAD.
THIS WOULD LEAD TO MORE TYPICAL POOR DRAINAGE FLOODING ISSUES. A
WARM, MUGGY NIGHT IS LIKELY WEDNESDAY NIGHT AS WELL WITH PLENTY OF
CLOUDCOVER TO KEEP TEMPERATURES UP.

THURSDAY THROUGH FRIDAY NIGHT: THE FRONTAL BOUNDARY WILL LIKELY
SLOWLY SAG TO OUR SOUTH IN THIS TIMEFRAME WITH THE POTENTIAL FOR A
WAVE OF LOW PRESSURE LATE THURSDAY TO BUCKLE IT BACK NORTH FOR A
SHORT PERIOD. THIS KEEPS A SHOWER/STORM CHANCE GOING AS WELL INTO
FRIDAY. AFTER THE PASSAGE OF THE FRONT, A COOLER AIRMASS WILL
ADVECT INTO THE REGION. MODELING DOES DIFFER ON HOW FAST THE FRONT COMES
THROUGH THE REGION. THE 00Z 7/7 NAM AND ECMWF ARE SLOWER AND TAKE A
LOW PRESSURE SYSTEM INTO THE EASTERN LAKES/ NORTH OF OUR REGION,
BRINGING RENEWED WARM AND INSTABILITY ADVECTION INTO THE REGION
LATE THURSDAY (WARM FRONT) BEFORE SENDING THE FRONT BACK SOUTH ON
FRIDAY. THESE POSSIBILITIES PLACE A HIGHER SHEAR ENVIRONMENT IN
THE REGION COUPLED WITH THE INCREASING INSTABILITY LATE THURSDAY,
MORE OF A SEVERE THREAT. THE MORE PROGRESSIVE SOLUTIONS AKA THE
GFS AND CMC WEAKEN THE LOW PRESSURE TO OUR SOUTH. OUR FORECAST
RAISES POPS AND SETS UP A QPF MAX AREA ACROSS NORTHERN PARTS OF
THE FORECAST AREA THURSDAY AND THURSDAY NIGHT. THE NAM DOES HAVE A
BIAS OF TRACKING LOWS TO FAR NORTH IN THE LAST 24-36 HOURS OF
MODEL RUNS. SO THIS FORECAST DID NOT FULLY JUMP ON THE BOARD WITH
THE SLOWER MOVING FURTHER NORTH FRONTAL IDEA. IT WILL BE COOLER AS
WELL WITH A SOMEWHAT MORE REFRESHING AIRMASS COMING IN BEHIND THE
FRONT. RAIN CHANCES MAY LINGER ON FRIDAY IN THE DELMARVA.

SATURDAY THROUGH MONDAY NIGHT: ANOTHER WARM FRONT WILL PUSH
NORTHWARD INTO THE REGION LATER IN THE WEEKEND. SO THE SOMEWHAT
COOLER AND LESS HUMID AIRMASS WILL GET REPLACED BY ANOTHER ROUND OF
HOT AND HUMID WEATHER EARLY NEXT WEEK. DID TREND TEMPERATURES THAN
THE ENSEMBLE GUIDANCE BY EARLY NEXT WEEK. THE ENSEMBLE GUIDANCE
POPS WERE ALSO LOWERED IN THIS FORECAST GIVEN NORMAL 5-7 DAY
FORECAST UNCERTAINTIES.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

AMD NOT SKED AT KACY DUE TO LACK OF TIMELY AUTOMATED TRANSMISSION
OF METAR INFORMATION WHICH WITH IFR CONDITIONS.

THROUGH ABOUT 12Z...WIDESPREAD CIGS AOB 1200 FEET WITH AREAS IFR
STRATUS, ESPECIALLY VCNTY KABE/KTTN. 3-5 MILE FOG SHOULD DEVELOP
BY 10Z BUT IT MAY NOT DROP BELOW 2 OR 3 MILES EXCEPT ON THE RIDGES
OF THE POCONOS AND KITTATINNYS IN NE PA AND NW NJ WHERE LIFR AND
RIDGES MAY BE OBSCURED. SOUTHEAST WIND 5-10 KT BECOMES SOUTH
SOUTHWEST BY 12Z. SCATTERED SHOWERS AT 0855Z REFUSE TO QUIT I-95
NWWD.

AFTER 12Z...AS THE WIND SHIFTS MORE SOUTHWESTERLY, CONDITIONS
IMPROVE TO VFR SCT-BKN AOA 3500 FEET BETWEEN 12Z AND 14Z. CIGS
RISE FURTHER TO AOA 5000 FT EARLY THIS AFTERNOON THEN CLEAR FROM
SW TO NE LATER IN THE DAY AS THE PWAT DROPS. SCATTERED IFR SHOWERS
AND ISOLATED TSTMS IN THE 15Z-21Z TIME FRAME, MAINLY ALONG AND NW
OF I-95. A COUPLE OF THESE STORMS MAY PRODUCE A GUST TO 35 KT.

GRADIENT SOUTHWEST WIND GUSTS 15-20 KT AT ALL SITES DURING THE
AFTN.

TONIGHT...VFR CLEAR THIS EVENING THEN A DECK OF BKN CIGS AOA 5000
FT ARRIVES N OF I-78 (NEAR KABE AND KRDG) AFTER 04Z/8 ASSOCIATED
WITH A DECAYING BAND OF CONVECTION AHEAD OF THE EWD MOVING COLD
FRONT.

OUTLOOK...

WEDNESDAY THROUGH THURSDAY NIGHT: POTENTIAL MVFR AND IFR
RESTRICTIONS IN SHOWERS AND THUNDERSTORMS, HIGHEST CHANCES EACH
AFTERNOON AND EVENING. WEST-SOUTHWEST WIND GUSTS AT OR UNDER 20
KNOTS.

FRIDAY THROUGH SATURDAY NIGHT: VFR. WINDS AT OR UNDER 10 KNOTS,
MAINLY NORTHERLY.

&&

.MARINE...
SUB-SCA CONDITIONS EXPECTED THROUGH THIS EVENING. ATLC SEAS MAY
INCREASE TO THE HAZARDOUS 5 FT THRESHOLD LATE TONIGHT BUT NO SCA
ATTM SINCE DURING WARM AIR ADVECTION, GUIDANCE TENDS TO HAVE A
HIGH BIAS ON THE SEAS.

WINDS WILL BECOME SW TODAY AND INCREASE TO 15 TO 20 KT LATE TODAY
AND TONIGHT.

OUTLOOK...

SUB-SCA WINDS AND SEAS EXPECTED. ANY WIND GUSTS LOOK TO
REMAIN BELOW 20 KNOTS, MORE SOUTHWESTERLY THROUGH WEDNESDAY NIGHT THEN
MORE NORTHERLY THROUGH SATURDAY NIGHT. SEAS AROUND FOUR FEET ON
WEDNESDAY AND THURSDAY. THE HIGHEST CHANCE OF THUNDERSTORMS IS
WEDNESDAY AFTERNOON AND EVENING THEN AGAIN LATER THURSDAY.

&&

.RIP CURRENTS...
FORECASTING A LOW RISK TODAY USING A 3 FT 5 SECOND SOUTHERLY SWELL
THIS AFTERNOON OR EARLY THIS MORNINGS 2 FT 9 SECOND. COMBINE THAT
WITH A SOUTHERLY WIND THAT INCREASES TO 12-13 KT THIS AFTERNOON
AND WE GET A LOW RISK ALONG OUR WATERS.

WE CANNOT OVEREMPHASIZE...LOW RISK DOES NOT MEAN NO RISK. TRANSITORY
AND RECURRENT RIP CURRENTS OCCUR EVERY DAY. PLAY IT SMART AND SWIM
SAFELY IN THE PRESENCE OF A LIFEGUARD WHO KNOWS WHAT THEY`RE DOING
IF A RESCUE IS NEEDED. THEY ARE THERE INSTANTLY TO SAVE LIVES INSTEAD
OF BE NOTIFIED TO RECOVER.

MEDIA COMMUNICATION OF THE INCREASED RIP CURRENT DANGER SWIMMING
AWAY (OUTSIDE) FROM THE WATCHFUL EYES OF LIFEGUARDS IS VERY
IMPORTANT. RAISING AWARENESS CAN BE A LIFESAVER, FOR ALL AGES BUT
EVEN MORE SO FOR THE VULNERABLE 10-29 AGE MALES THAT MAKE THE
PREPONDERANCE OF RIP CURRENT RELATED FATALITIES. INTERVIEWS CAN
BE CONDUCTED. JUST CONTACT US.

&&

.EQUIPMENT...
KACY DATA MAY NOT BE TRANSMITTING THOUGH WE SEE IT INTERNALLY IN THE
OFFICE. NO NOTAM.

&&

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

&&

$$
SYNOPSIS...GAINES
NEAR TERM...DRAG  504
SHORT TERM...DRAG 504
LONG TERM...GAINES
AVIATION...DRAG/GAINES 504
MARINE...DRAG/GAINES 504
RIP CURRENTS...504
EQUIPMENT...504


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