Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 011425
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1025 AM EDT FRI AUG 1 2014

.SYNOPSIS...
SEVERAL WEAK SURFACE TROUGHS WILL MOVE INTO THE AREA TODAY, BEFORE
HIGH PRESSURE OVER THE WESTERN ATLANTIC PUSHES AN OFFSHORE WARM
FRONT NORTHWESTWARD ACROSS THE EAST COAST THIS WEEKEND. SEVERAL
DISTURBANCES WILL MOVE NORTHEAST ALONG THIS BOUNDARY THROUGH THE
WEEKEND. ANOTHER COLD FRONT WILL THEN MOVE ACROSS THE AREA LATE
TUESDAY INTO WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH THE UPDATE, WE RAISED DEWPOINTS ACROSS THE REGION BY TWO TO
THREE DEGREES USING THE LAV/LAMP GUIDANCE TO REFLECT CURRENT OBS
AND TRENDS THROUGH LATE MORNING AND INTO THE AFTERNOON. NOT MUCH
ADJUSTMENT WAS NEEDED TO HOURLY TEMPS, AND TODAYS MAXIMUM TEMPS
LOOK ON TRACK, ESPECIALLY WITH THE INCOMING MID AND HIGH CLOUDS.
WE DID ADJUST POPS DOWN A BIT THROUGH THE REMAINDER OF THE
MORNING, BASED ON CURRENT RADAR TRENDS AND HRRR GUIDANCE AS
SHOWERS ARE HAVING A DIFFICULT TIME MAKING IT INTO OUR SOUTHERN
DELMARVA ZONES, WITH SOMEWHAT DRIER MID/UPPER LEVEL AIR. WE ALSO
CONFINED ANY ISOLATED TO SCATTERED TSTORM CHANCES TO THE
AFTERNOON.

OTHERWISE, AN ACTIVE WEATHER PATTERN WILL BE RAMPING UP IN THE
NEAR AND SHORT TERM. FIRST...A SHORT WAVE TROUGH CURRENTLY OVER
VIRGINIA WILL MOVE OVER THE REGION BY 18Z. THERE IS CURRENTLY AN
AREA OF MOSTLY STRATIFORM PRECIPITATION ASSOCIATED WITH THIS
TROUGH. HOWEVER...AS THIS TROUGH PROPAGATES NORTHEAST...IT WILL
ENCOUNTER DRIER AIR ESPECIALLY IN THE MID AND UPPER LEVELS.
THUS...EXPECT CLOUDS, BUT NOT NECESSARILY WIDESPREAD PRECIP TO
MOVE INTO THE REGION EARLY IN THE DAY. WHAT SHOWERS AND STORMS DO
MOVE INTO THE REGION SHOULD BE LIMITED IN COVERAGE, AT LEAST AT
FIRST. IT DOES APPEAR THAT THERE WILL BE ENOUGH INSTABILITY TO
SUPPORT THUNDERSTORMS. THE NAM EVEN SHOWS ML CAPE VALUES NEAR 1000
J/KG. HOWEVER, IT SEEMS THAT THE NAM IS OVERLY AGGRESSIVE WITH LOW
LEVEL MOISTURE RETURN, AND THUS TOO HIGH ON THE INSTABILITY. ALSO,
THE PERSISTENT CLOUD COVER SHOULD HELP TO KEEP SURFACE
TEMPERATURES DOWN SLIGHTLY, FURTHER LIMITING INSTABILITY. THUS,
THE GFS SEEMS TO HAVE A BETTER HANDLE ON THIS ASPECT, WITH ML CAPE
VALUES GENERALLY LESS THAN 500 J/KG.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
RIGHT ON THE HEALS OF THE FIRST SHORT WAVE TROUGH TODAY, A SECOND
UPPER LEVEL SHORT WAVE TROUGH APPROACHES THE REGION. THIS, COUPLED
WITH THE MOIST SOUTHERLY AND SOUTHWESTERLY FLOW, AND A SLOW MOVING
WARM FRONT WHICH APPROACHES THE REGION LATE TONIGHT, WILL MEAN
INCREASED PRECIP CHANCES FOR MUCH OF THE REGION. THIS IS ESPECIALLY
TRUE FOR THE EASTERN HALF OF THE REGION WHICH SHOULD HAVE SLIGHTLY
BETTER LIFT, AND SEE PRECIPITABLE WATER VALUES CLIMB TO NEAR 2
INCHES BY LATE IN THE PERIOD.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
OVERALL THE MEDIUM RANGE IS ON PAR WITH ONE ANOTHER WITH THE
SYNOPTIC FEATURES THROUGH EARLY NEXT WEEK. THE EARLY PART OF THE
LONGTERM PERIOD, THIS WEEKEND, IS STILL VIEWED AS AN AVERAGE TO
SLIGHTLY BELOW AVERAGE CONFIDENCE, INLAND, AS THE TIMING AND
PLACEMENT OF SEVERAL SMALLER IMPULSES AND COASTAL BAROCLINIC ZONE
INTERACTION OCCURS.

SATURDAY...STARTING TO SEE SOME BETTER CONSENSUS, THOUGH STILL NOT
GREAT, AND ACCORDING TO THE 01/00Z DATA THE NON-NCEP MEMBERS HAVE JUMPED
MORE TOWARDS THE NCEP GUIDANCE IN KEEPING THE BAROCLINIC ZONE AND
ITS SUBSEQUENT SURFACE WAVES MORE OFFSHORE...EC INCLUDED. THE GEFS
HAS BEEN PRETTY CONSISTENT THE PAST FEW NIGHTS WHILE THE EC
ENSEMBLES HAVE BEEN TRENDING LESS CONFIDENT IN THE MID-LEVELS AND AT
MORESO AT THE SURFACE. PWATS INCREASE UPWARDS 1.5 TO 1.75 INCHES BY
SATURDAY EVENING WITH GREATER AMOUNTS EAST OF THE DELAWARE RIVER.
UPPER LEVEL JET DYNAMICS WITH THE RIGHT ENTRANCE REGION SITTING
ACROSS THE MID-ATLANTIC AND AMPLE SUB-TROPICAL MOISTURE AVAILABLE
FOR THE PASSING WAVES TO TAP INTO, WE COULD BE LOOKING AT A HEAVY
RAIN POTENTIAL...GREATER CHANCES EAST OF THE RIVER CLOSER TO THE
COAST AND FRONTAL BOUNDARY. TEMPERATURES WILL STRUGGLE TO GET OUT OF
THE 70S IN A LOT OF PLACES WITH LOTS OF CLOUD COVER, RAIN, AND
EASTERLY FLOW. THE METMOS SEEMED TOO LOW, AS IT USUALLY GOES CRAZY
WITH STRATUS WHEN RAIN IS FORECASTED. ANY BREAKS IN THE CLOUDS FOR
AN HOUR OR TWO COULD EASILY BOOST SOME LOCATIONS INTO THE LOW-80S.

SUNDAY...THERE LOOKS TO BE A DRIER PERIOD, AT LEAST THE FIRST HALF
OF THE DAY BEFORE A STRONGER MID-LEVEL WAVE NEARS FROM THE WEST
DURING THE AFTERNOON HOURS...THIS IS THE KICKER VORT LOBE. COLD POOL
INTERACTION ALOFT AND MINIMAL SURFACE HEATING SHOULD BE ENOUGH FOR
SCATTERED SHOWERS WITH VERY ISOLATED CONVECTION. AGAIN, FRONTAL
BOUNDARY STILL CLOSE TO THE REGION SO WE HAVE LIKELY POPS ACROSS
SOUTHERN DELMARVA AND ALONG THE NJ COAST. TEMPERATURES MAY END UP
BEING A DEGREE OR TWO WARMER THAN SATURDAY WITH POSSIBLY MORE BREAKS
IN THE CLOUDS.

MONDAY...DEPENDING ON THE TIMING OF MORE MID-LEVEL SHORTWAVES, OR
LACK THEREOF, MONDAY COULD END UP BEING A MOSTLY DRY DAY. EC DOES
NOT SHOW MUCH FORCING WHILE THE GFS KEEPS A FEW IMPULSES SHEARING
THROUGH. GEFS PAINTS A PRETTY BROAD AREA OF AT LEAST CHANCE POPS AND
GIVEN THE UNCERTAINTY AT THIS POINT DID NOT WANT TO CHANGE TOO MUCH
DURING THE TIMEFRAME...CONTINUE CHANCE POPS WITH MODERATING
TEMPERATURES.


TUESDAY - THURSDAY...CONTINUING CYCLONIC FLOW ALOFT MAY BE ENOUGH
FOR ISOLATED SHOWER ACTIVITY EACH AFTERNOON, OTHERWISE A MOSTLY DRY
FORECAST IS EXPECTED THIS TIMEFRAME. WEAK FRONT MAY CROSS ON
WEDNESDAY WITH OUR BEST CHANCES AT SCATTERED ACTIVITY. TEMPERATURES
MODERATE EVEN MORE AND SHOULD END UP BEING NORMAL.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD;
ALTHOUGH, SOME MVFR CIGS ARE STILL LINGERING FOR OUR WESTERN TAF
SITES, NAMELY KABE AND KRDG. THIS SHOULD IMPROVE TO VFR CIGS FOR
THESE SITES BY AROUND 16Z. THE BIGGER QUESTION FOR TODAY WILL BE
TIMING OF SHRA AND TSRA. VERY LOW CONFIDENCE ON THE TIMING OF ANY
SHRA AND TSRA THROUGH THE DAY TODAY, BUT IF ANY DO MOVE OVER
TERMINALS THROUGH THE DAY, EXPECT VFR CONDITIONS EVEN WITH THE
PRECIPITATION. COVERAGE THROUGH 00Z IS EXPECTED TO BE TOO LIMITED
TO INCLUDE IN THE TAFS AT THIS TIME. AFTER 00Z...CHANCE FOR SHRA
INCREASES. THERE MAY REMAIN ISOLATED TSRA AFTER SUNSET, BUT EXPECT
THE RISK FOR LIGHTNING TO DECREASE BY LATE EVENING, AND AT THIS
TIME WE HAVE KEPT ANY MENTION OF TSRA OUT OF THE TAFS AS ANY
OCCURENCE LOOKS TO BE ISOLATED. FOR THE PERIOD BETWEEN 00 AND
12Z, EXPECT SHRA TO BE MORE WIDESPREAD ESPECIALLY FOR LOCATIONS
ALONG AND EAST OF THE DELAWARE RIVER, INCLUDING KPHL, KPNE, KTTN,
KILG, KMIV, AND KACY. MVFR VISIBILITIES WILL BE POSSIBLE WITH ANY
OVERNIGHT SHRA.

OUTLOOK...
SATURDAY - SUNDAY...MOSTLY VFR WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS POSSIBLE EACH AFTERNOON. HEAVY RAIN MAY OCCUR CLOSER
TO THE COAST. MVFR/IFR CONDITIONS LIKELY IN SHOWERY ACTIVITY.
EASTERLY FLOW IN PLACE. MEDIUM CONFIDENCE.

MONDAY - TUESDAY...VFR. ISOLATED SHOWERS POSSIBLE ON EACH AFTERNOON.
MEDIUM CONFIDENCE.

&&

.MARINE...
EXPECT WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY TODAY AND
TONIGHT WITH WINDS STAYING NEAR OR BELOW 20 KT AND SEAS BETWEEN 2
AND 3 FEET.

OUTLOOK...
FRIDAY - TUESDAY...SUB-SCA CONDITIONS ARE EXPECTED ACROSS OUR
WATERS THIS PERIOD.

&&

.RIP CURRENTS...
THE RISK OF RIP CURRENTS WILL INCREASE TO MODERATE TODAY AS THE
WINDS SHIFT TO SOUTHEASTERLY.

&&

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

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...JOHNSON/KLINE
SHORT TERM...JOHNSON
LONG TERM...HEAVENER
AVIATION...HEAVENER/JOHNSON/KLINE
MARINE...HEAVENER/JOHNSON
RIP CURRENTS...JOHNSON





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