Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 251543
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1143 AM EDT MON AUG 25 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL OF OUR WEATHER THROUGH TUESDAY.
A COLD FRONT SHOULD SLIDE SOUTHEASTWARD INTO THE MID ATLANTIC REGION
DURING MID WEEK. IN THE WAKE OF THE COLD FRONT, HIGH PRESSURE
BUILDS IN DURING THURSDAY AND FRIDAY. A WARM FRONT MAY LIFT NORTHWARD
NEAR OUR AREA SATURDAY, THEN A COLD FRONT APPROACHES SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL RIDGE THAT
CONTINUES TO BUILD INTO THE NORTHEAST AND MID ATLANTIC REGION. SINCE
WE ARE NEAR THE EASTERN EDGE OF THIS RIDGE, THE FLOW UP THROUGH
ABOUT 500 MB IS STILL ONSHORE. IN ADDITION, SURFACE HIGH PRESSURE
CENTERED NEAR NORTHERN NEW YORK STATE WILL CONTINUE TO WEDGE DOWN
INTO THE MID ATLANTIC REGION.

DESPITE THE ONSHORE FLOW, THE AIRMASS HAS DRIED SOME MORE SINCE
YESTERDAY ESPECIALLY JUST ABOVE THE SURFACE. THIS IS EVIDENT IN THE
12Z RAOBS FROM STERLING, VA AND UPTON, NY. WHILE SOME CUMULUS SHOULD
OCCUR ESPECIALLY INLAND WITH A NARROW MOIST LAYER NEAR 850 MB, IT
SHOULD BE LESS THAN YESTERDAY GIVEN SOME WARMING ALOFT AND SOME
INCREASE IN SUBSIDENCE. SOME THIN HIGH CLOUDS SHOULD BE AROUND AT
TIMES ESPECIALLY ACROSS THE WESTERN ZONES. A NORTHEASTERLY LOW-LEVEL
FLOW SHOULD TURN MORE EAST AND THEN SOUTH-SOUTHEAST GIVEN THE WEAKER
PRESSURE GRADIENT AND FLOW. THE DELMARVA HOWEVER MAY HOLD ONTO A
NORTHEAST OR EAST FLOW LONGER. THIS TRANSLATES TO PROBABLY SOME
ENHANCEMENT OF A SEA/BAY BREEZE AS THE LAND HEATS UP. IT SHOULD BE
COOLER CLOSER TO THE COAST AND ALSO THE DELMARVA GIVEN THE LINGERING
EFFECTS OF THE OCEAN INFLUENCE. THE DEW POINTS IN GENERAL ARE
ANTICIPATED TO BE IN THE COMFORTABLE RANGE TODAY, WITH SOME DECREASE
PROBABLY OCCURRING WITH HEATING/MIXING.

THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS,
THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST ESPECIALLY WITH
TEMPERATURES AND DEW POINTS. SOME INLAND LOCATIONS ARE WARMING A
BIT FASTER THAN FORECAST SO FAR, THEREFORE THIS WAS ACCOUNTED FOR
IN THE ADJUSTMENTS. NO MAJOR CHANGES WERE MADE TO THE HIGH
TEMPERATURES ATTM, WHICH WERE MOSTLY A NAM/GFS MOS BLEND.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE AFOREMENTIONED HIGH WILL REMAIN PARKED OVER THE AREA SO A CLEAR
SKY, AND DRY CONDS ARE ANTICIPATED.  AGAIN, MOS GUID WAS IN GOOD
AGREEMENT AND GENLY FOLLOWED.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
CONSIDERABLY DIFFERENT MODEL SOLUTIONS FROM BOTH THE GFS AND ECMWF
THAN THE MODEL RUNS 24 HOURS AGO.

TUESDAY...START TO SEE SOUTHWESTERLY FLOW DEVELOP IN THE LOW
LEVELS AT THE SAME TIME AN UPPER LEVEL SHORT WAVE RIDGE PIVOTS
SOUTHEAST OVER THE REGION EARLY IN THE DAY. THE COMBINATION OF
BOTH OF THESE WILL RESULT IN RATHER PRONOUNCED WARM UP FOR
TUESDAY. HIGHS COULD BE AS MUCH AS 5 DEGREES ABOVE NORMAL.

WEDNESDAY AND THURSDAY...THE BIGGEST CHANGE IN THE LATEST LONG
RANGE MODEL RUNS IS WITH THE TIMING OF THE COLD FRONT. WHILE THERE
HAD BEEN A TREND UP THROUGH YESTERDAY`S 00Z MODEL RUNS OF DELAYING
THE ARRIVAL OF THE COLD FRONT (OR NOT EVEN BRINGING IT THIS FAR
SOUTH AT ALL), THE 12Z RUNS, AND NOW THE LATEST 00Z RUNS HAVE SPED
UP THE ARRIVAL OF THE FRONT. SHOWING THE FRONT ARRIVING IN OUR
REGION ON WEDNESDAY OR WEDNESDAY NIGHT. INTERESTINGLY, TO START
THIS PERIOD, MID AND UPPER LEVEL FLOW IS NEARLY ZONAL (SUGGESTING
THAT THE FRONT MAY NOT DIG AS FAR SOUTH). HOWEVER, BOTH THE GFS
AND ECMWF SHOW AN UPPER LEVEL SHORT WAVE TROUGH QUICKLY DIGGING
SOUTHEAST OUT OF NORTH CENTRAL CANADA, CROSSING THE NORTHEASTERN
U.S. BY WEDNESDAY NIGHT. THERE WILL BE SOME CHANCE OF
THUNDERSTORMS ALONG THE FRONT, THOUGH WITH DRIER SOUTHWESTERLY
FLOW IN THE PERIODS LEADING UP TO THIS, THERE IS SOME QUESTION OF
MOISTURE AVAILABILITY, AND THUS HOW WIDESPREAD PRECIPITATION WILL
BE. THE LIMITED LOW LEVEL MOISTURE ALSO HAS AN IMPACT ON
INSTABILITY, AS DOES THE EXPECTED NIGHT TIME ARRIVAL OF THE FRONT.
THUS...AT THIS TIME SEVERE STORMS SEEM UNLIKELY, BUT IF THE FRONT
ARRIVES DURING DAY LIGHT HOURS, NOT COMPLETELY OUT OF THE
QUESTION.

ON A SIDE NOTE FOR THIS PERIOD, CRISTOBAL IS STILL EXPECTED TO BE
WELL OUT TO SEA, AND BY THIS POINT RACING FURTHER AWAY FROM THE
REGION. THUS, THE ONLY IMPACTS WE ARE EXPECTING FROM CRISTOBAL ARE
LONG PERIOD SWELLS AND AN ENHANCED RIP CURRENT RISK, THOUGH THE
TIMING OF BOTH IS UNCERTAIN.

FRIDAY...THE CONTINENTAL POLAR AIR MASS SETTLES IN OVER THE
REGION, ALBEIT BRIEFLY, BY FRIDAY, LEADING TO A COOL AND DRY DAY.

FRIDAY NIGHT THROUGH SUNDAY...AS THE HIGH SHIFTS NORTHEAST OFF THE
COAST, LOW LEVEL SOUTHERLY FLOW RETURNS BRINGING A WARMING TREND,
AND MORE MOISTURE. THIS COULD SET THE STAGE FOR THE BEST CHANCE OF
THUNDERSTORMS OVER THE NEXT WEEK EITHER SATURDAY OR SUNDAY AS A
SECOND COLD FRONT COULD APPROACH THE REGION.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR. NORTHEAST WINDS NEAR 10 KNOTS, MOSTLY
BECOMING EAST AND THEN SOUTHERLY LATER THIS AFTERNOON.

TONIGHT...VFR OVERALL. LOCALIZED FOG MAY OCCUR TOWARD MORNING,
HOWEVER IT MAY BE SHALLOW GROUND FOG. OUR CONFIDENCE IS LOW THAT IT
WOULD HAVE AN IMPACT ON ANY TERMINALS, THEREFORE IT WAS NOT INCLUDED
AT THIS TIME. SOUTHERLY WINDS AROUND 5 KNOTS, BECOMING LIGHT AND
VARIABLE OR CALM.

TUESDAY...VFR. LIGHT AND VARIABLE WINDS TO START, BECOMING
SOUTHWESTERLY 5-8 KNOTS. A SEA/BAY BREEZE IN THE AFTERNOON MAY
AFFECT KACY, KMIV AND KILG WITH MORE OF A SOUTHEAST WIND.

OUTLOOK...
TUESDAY NIGHT...VFR CONDITIONS EXPECTED.

WEDNESDAY THROUGH THURSDAY...MOSTLY VFR CONDITIONS EXPECTED. A
SMALL RISK OF THUNDERSTORMS AS A COLD FRONT COULD PUSH THROUGH
WEDNESDAY OR THURSDAY.

FRIDAY...VFR CONDITIONS LIKELY.

&&

.MARINE...
THE SCA WILL REMAIN IN EFFECT AS PREV ISSUED MAINLY FOR SEAS DUE TO
THE NELY FLOW.  THE FLOW SHOULD EVENTUALLY BECOME MORE SLY THEN SWLY
AND THIS SHOULD ALLOW THE SEAS TO SLOWLY SUBSIDE, AFTER WHICH TIME
NO ADDITIONAL MARINE HEADLINES WILL BE NECESSARY FOR THE REMAINDER
OF THE NEAR AND SHORT TERM PDS.

OUTLOOK...
TUESDAY...WINDS AND SEAS ARE EXPECTED TO BE BELOW SMALL CRAFT
ADVISORY CRITERIA.

WEDNESDAY THROUGH FRIDAY...WINDS WILL STAY BELOW SCA CRITERIA. WE
COULD BEGIN TO SEE LONG PERIOD SWELLS ASSOCIATED WITH TROPICAL
CYCLONE CRISTOBAL, WHICH WILL STAY WELL OUT TO SEA, AS EARLY AS
WEDNESDAY. HOWEVER, TIMING AS WELL AS WAVE HEIGHTS ASSOCIATED WITH
THESE SWELLS IS STILL VERY UNCERTAIN AT THIS TIME.

&&

.RIP CURRENTS...
THE RISK OF DANGEROUS RIP CURRENTS IS HIGH THROUGH THIS EVENING. THE
COMBINATION OF TODAY`S NEW MOON, LONG FETCH ONSHORE FLOW EARLY AND
THEN LONG PERIOD SWELLS ASSOCIATED WITH TROPICAL STORM CRISTOBAL
LATER IN THE WEEK SHOULD KEEP AN ELEVATED RISK OF DANGEROUS RIP
CURRENTS.

TROPICAL STORM CRISTOBAL IS FORECAST TO TRACK WELL EAST OF THE MID
ATLANTIC COAST LATER THIS WEEK.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...HIGH RIP CURRENT RISK UNTIL 11 PM EDT THIS EVENING FOR NJZ014-
     024>026.
DE...HIGH RIP CURRENT RISK UNTIL 11 PM EDT THIS EVENING FOR DEZ004.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
     ANZ452>455.

&&

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



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