-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 141804
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
204 PM EDT TUE MAY 14 2013

.SYNOPSIS...
HIGH PRESSURE WILL INFLUENCE OUR REGION TODAY AND THEN SETTLE OFF TO
OUR SOUTH AND EAST LATER TONIGHT. DURING WEDNESDAY, A WARM FRONT
STRETCHING FROM MICHIGAN TO VIRGINIA WILL LIFT NORTHWARD ACROSS OUR
AREA, FOLLOWED BY A WEAK COLD FRONT CROSSING THE MID ATLANTIC BY
THURSDAY NIGHT. WEAK HIGH PRESSURE IS EXPECTED FOR FRIDAY AND
SATURDAY. EARLY NEXT WEEK, A DEVELOPING LOW PRESSURE SYSTEM OVER THE
PLAINS STATES WILL SLOWLY TRACK EASTWARD.

&&

.NEAR TERM /THROUGH TONIGHT/...
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12Z/14 SOUNDINGS OFFER 59-62F FULL SUN TODAY. SINCE WAA IS IN PROGRESS
TODAYS MAX`S AND FCST LOOK ON TARGET AS OF 1230 PM...MAYBE A DEGREE
ON THE HIGH SIDE....ESPECIALLY WITH MODELED CIRRUS COMING TO FRUITION.

NUMEROUS INQUIRIES ON THE VISION OF A HALO...GOOGLE IT FOR THE BEST
EXPLANATION...BUT DONT SPEND ANY TIME LOOKING AT THE SUN...WHICH CAN
BE A SUBSTANTIAL IRREPARABLE VISION HAZARD.

TEMPS WILL BE SEVERAL DEGREES WARMER THAN MONDAY, BUT STILL REMAIN
WELL BELOW NORMAL FOR MID-MAY...AROUND 10 TO 12 DEGREES BELOW NORMAL.

RAPIDLY THICKENING LOWERING CIGS ...THE BAND YOU SEE ON SATELLITE
IMAGERY FROM MICHIGAN TO W PTNS PA AND NYS. SCT LIGHT SHOWERS
EXPECTED...MOSTLY TRACE...AFTER MIDNIGHT AND MODELED THE NSSL WRF
AND NOW THE RAP...FLYING SEWD 30-40 KT. LIGHT S WIND IN THE WAA
PATTERN BEHIND THE DEPARTING SFC HIGH OFF THE SE USA COAST.
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&&

.SHORT TERM /WEDNESDAY/...
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WEDNESDAY...THE 12Z GFS LOOKS LIKE MY IDEA OF A BEST MODEL SOLN OF
THE 12Z INTERNATIONAL SUITE. WILL MERGE THE MORE CONSERVATIVE 12Z/14
RGEM/NAM/UKMET SOLNS. THE 12/14 GFS IMO HAS THE RIGHT IDEA ABOUT
STRONG CONVECTION AND PROBABLY STREAMING EAST SOUTHEAST FROM
SOUTHERN PA ACROSS S NJ AND OR THE DELMARVA LATE IN THE DAY WEDNESDAY.
SPC 1715Z SWODY2 ASSESSMENT MATCHES MY THINKING.

THE APPROACHING WARM FRONT WILL GENERATE SCATTERED SHOWERS AND
THUNDERSTORMS. PLACEMENT AND TIMING UNCERTAIN AND MOST OF THE DAY
SHOULD BE RAINFREE. THE INCREASING BOUNDARY LAYER MOISTURE MAY BE
OVERDONE BY THE MODELS, THUS LIMITING INSTABILITY AND THE POTENTIAL
FOR STRONGER CONVECTIVE ACTIVITY. WE MAINTAIN MAINLY CHANCE POPS
ACROSS THE REGION, THOUGH, FOR SCATTERED SHWRS/T-STORMS AS MU
CAPES AND LI VALUES SHOW SUFFICIENT INSTABILITY IN THE LATE
WEDNESDAY AFTN TO EVENING TIMEFRAME, ESPECIALLY ACROSS THE
DELMARVA REGION AND ADJACENT AREAS OF NEARBY SOUTHEAST PA AND
SOUTHERN NJ.

FWIW...THE GFS HAS GRIDDED LAMP TSTM PROBS IN W NYS AND NW PA BY
14Z

THERE IS MODEL REMNANTS OF AN EML NOW SPREADING EWD FROM THE MIDWEST
THAT SUPPORTS CONCERN FOR HAILERS....INCREASING THE 700-500MB
LAPSE RATES LATE IN THE DAY.

MORE THAN ADEQUATE BULK SHEAR FOR SVR WIND... AND SO THE QUESTION
BECOMES...IS THERE ENOUGH MOISTURE TO SUPPORT TSTM GENERATION. 12Z/14
GFS ML CAPE IS ONLY 600J LATER IN THE DAY AND SO WILL NOT WORD
HAIL OR GUSTY WINDS IN THE ZONE PRODUCTS.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE WARM FRONT IS PROGGED TO BE NORTH OF OUR REGION BY EARLY
THURSDAY, WITH SOME SUN AND WARM TEMPERATURES IN STORE FOR
THURSDAY. MUCH OF THE REGION SHOULD PEAK IN THE UPPER 70S TO LOWER
80S FOR HIGH TEMPERATURES. BY MID TO LATE DAY, A WEAK COLD FRONT
WILL BE APPROACHING FROM THE WEST, AND THERE LOOKS TO BE ENOUGH
MODELED INSTABILITY TO TRIGGER SCATTERED SHWRS/T-STORMS, WITH THE
BEST CHANCES OVER OUR DELMARVA REGION. THIS FRONT MAY STALL FOR A
TIME JUST TO THE SOUTH OF OUR AREA, ESPECIALLY THROUGH THURSDAY
NIGHT AND INTO EARLY FRIDAY, AND WE HAVE ADDED POPS ACROSS OUR
SOUTHERN ZONES TO INDICATE AN ONGOING CHANCE FOR SCATTERED
SHWR/T-STORM ACTIVITY. OTHERWISE FARTHER NORTH, THROUGH EASTERN PA
AND MUCH OF NJ, MOST OF FRIDAY AND SATURDAY SHOULD FEATURE DRY
CONDITIONS WITH SOME SUN AND MILD TEMPERATURES REACHING INTO THE
MIDDLE AND UPPER 70S. WEAK HIGH PRESSURE WILL THEN SHIFT EAST AND
AWAY FROM THE REGION BY SUNDAY. FROM THERE, MODEL DIFFERENCES
INCREASE, BUT THE OVERALL PICTURE FROM SUNDAY AND INTO EARLY NEXT
WEEK HAS UNSETTLED WEATHER IN PLACE ACROSS OUR REGION, WITH THE
POTENTIAL FOR MORE SCATTERED SHWR/T-STORM ACTIVITY. WE USED A
BLEND OF WPC GUIDANCE WITH CONTINUITY AT THIS EXTENDED TIMEFRAME
AND KEPT CHANCE POPS IN PLACE.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

REMAINDER THIS AFTERNOON...VFR WITH CIRRUS DEVELOPING SEWD. WNW
WIND WIND GUSTS GENERALLY LESS THAN 17 KT.

TONIGHT...VFR CIGS AOA 7000 FT DEVELOPING FM NW TO SE WITH SCT
SPRINKLES OR LIGHT .02 SHOWERS STREAMING SEWD 30-40 KT AFTER 04Z.
LIGHT SOUTH SFC WIND.

WEDNESDAY...VFR SCT-BKN CLOUDS AOA 5000 FT WITH A SMALL CHANCE OF
A LEFTOVER SHOWER POSSIBLE IN THE MORNING BUT A BAND OF SCT-BKN
SHOWERS AND ISO STRONG TSTMS EXPECTED LATE IN THE DAY...PROBABLY
MOVING ESEWD THRU SE PA NEAR KPHL. SSW WIND GUSTS 15 KT IN THE
AFTN. STRONGER WLY GUST TO 35 KT `POSSIBLE` IN A LATE DAY TSTM
VCNTY KPHL.

OUTLOOK...
WEDNESDAY NIGHT...MOSTLY VFR CONDITIONS EXPECTED. SOME LOWERING TO
MVFR CIGS/VSBYS POSSIBLE IN SCATTERED SHWRS/T-STORMS, MAINLY
EVENING.

THURSDAY...MOSTLY VFR CONDITIONS. A WEAK COLD FRONT MAY TRIGGER
SCATTERED SHOWERS IN AFTN TO EVE, WITH POSSIBLE BRIEF LOWERING MVFR.

FRIDAY AND SATURDAY...MAINLY VFR CONDITIONS.
-- End Changed Discussion --

&&

.MARINE...
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HIGH PRESSURE WILL MOVE OVER THE SERN CONUS TODAY AND THEN FURTHER
EWD OVER THE SERN COASTAL WATERS TONIGHT. AS A RESULT THE WIND
AND SEAS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA THRU THE NEAR
AND SHORT TERM PDS.

WEDNESDAY...GUIDANCE INDICATES OUR COASTAL WATERS WILL REACH SCA
WIND GUSTS DURING THE DAYTIME WEDNESDAY WITH SEAS BUILDING TO 5
FT ON THE ATLC WATERS DURING THE AFTN GENERATED BY THE SLY FLOW
AHEAD OF AN APPROACHING WFRONT. FOR LOWER DE BAY THERE MAY BE A
PERIOD OF SCA WIND GUSTS WED AFTN BUT CONFIDENCE WAS NOT HIGH
ENOUGH AT THIS TIME TO INCLUDE THIS IN THE HEADLINE.

PROBABLY STARTING THE SCA A BIT SOONER ON THE ATLC WATERS
WEDNESDAY... AROUND 12Z. WILL LEAVE IT TO THE MID SHIFT TO ISSUE
FOR DE BAY.

OUTLOOK...
THE WARM FRONT WILL BE LIFTING NORTHEASTWARD THROUGH THE REGION
WEDNESDAY NIGHT. SCA CONTINUES THROUGH 12Z THURSDAY. THIS SCA MAY
POSSIBLY NEED TO BE EXTENDED FURTHER INTO THURSDAY, DEPENDING ON
HOW QUICKLY THE SEAS DIMINISH. ONCE SEAS SUBSIDE ON OUR COASTAL
WATERS THURSDAY, WE ANTICIPATE SUB-SCA CONDITIONS FOR OUR WATERS
THROUGH FRIDAY AND SATURDAY AS WEAK HIGH PRESSURE SETTLES ACROSS
THE REGION.
-- End Changed Discussion --

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM WEDNESDAY TO 8 AM EDT THURSDAY
     FOR ANZ450>455.

&&

$$
SYNOPSIS...KLINE
NEAR TERM...DRAG 204
SHORT TERM...DRAG 204
LONG TERM...KLINE
AVIATION...DRAG/KLINE 204
MARINE...DRAG/KLINE 204