708
FXUS61 KPHI 130105
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
905 PM EDT MON AUG 12 2013
.SYNOPSIS...
WEAK LOW PRESSURE APPROACHING FROM THE SOUTHWEST WILL MOVE
THROUGH OUR REGION DURING MIDDAY TUESDAY AND THEN OFFSHORE TUESDAY
EVENING ACCOMPANIED BY A COLD FRONTAL PASSAGE. LARGE SUMMER HIGH
PRESSURE OVER THE MIDWEST EARLY WEDNESDAY WILL GRADUALLY STRETCH
EASTWARD TO THE MID ATLANTIC COAST THURSDAY...THEN EDGE OFFSHORE
FRIDAY. A WARM FRONT FORMING ALONG THE SOUTHEAST COAST OF THE
UNITED STATES THIS WEEKEND WILL EDGE NORTHWARD BY EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
MID LEVEL SHORT WAVE WAS LOCATED OVER THE MID OHIO RIVER VALLEY
THIS EVENING. THERE WAS A FAIR AMOUNT OF PRECIPITATION ASSOCIATED
WITH THE FEATURE, ESPECIALLY EXTENDING SOUTHWARD INTO KENTUCKY AND
TENNESSEE. THE SHORT WAVE WILL PROGRESS EASTWARD DURING THE NIGHT
AND IT SHOULD BE APPROACHING OUR REGION TOWARD DAYBREAK.
WE WILL CONTINUE TO SEE THICKENING HIGH CLOUDS WITH SOME MID
LEVEL CLOUDS ARRIVING FROM THE WEST AFTER MIDNIGHT. SCATTERED
LIGHT SHOWERS MAY DEVELOP OVER OR MOVE INTO OUR NORTHWESTERN AND
WESTERN COUNTIES BETWEEN ABOUT MIDNIGHT AND 400 AM. HOWEVER, THE
MAIN PRECIPITATION EVENT IS NOT EXPECTED TO BEGIN ARRIVING UNTIL
CLOSE TO DAYBREAK. SHOWERS AND ISOLATED THUNDERSTORMS ARE
ANTICIPATED AT THAT TIME. MOST OF THE MODERATE TO HEAVY RAINFALL
IS NOT FORECAST TO AFFECT OUR REGION UNTIL AFTER SUNRISE.
THE CLOUD COVER AND THE INCREASING LOW LEVEL MOISTURE SHOULD KEEP
TEMPERATURES FROM DROPPING BELOW THE UPPER 60S AND LOWER 70S IN
MUCH OF OUR REGION OVERNIGHT. THE WIND WILL REMAIN LIGHT AND IT
MAY FAVOR THE SOUTH OR SOUTHEAST ON AND NEAR THE COASTAL PLAIN.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
SHOWER AND POSSIBLE THUNDERSTORM ACTIVITY IS EXPECTED TO BE
ONGOING AT THE START OF TUESDAY MORNING, SO THE MORNING RUSH WILL
LIKELY BE AFFECTED. THE AFOREMENTIONED SHORT WAVE IMPULSE AND
SURFACE FEATURE WILL BE SLIDING ACROSS THE AREA DURING THE MORNING
HOURS AHEAD OF THE APPROACHING COLD FRONT. PW VALUES WILL REMAIN
HIGH UNTIL THE FRONT MOVES THROUGH LATER IN THE DAY/EVENING, SO
HEAVY RAINFALL WILL REMAIN A POSSIBILITY. WHILE WIDESPREAD FLASH
FLOODING IS NOT CURRENTLY EXPECTED AS FLASH FLOOD GUIDANCE ACROSS
THE AREAS WHERE THE HEAVIEST RAIN IS EXPECTED IS FAIRLY HIGH.
HOWEVER, URBANIZED/POOR DRAINAGE FLOODING COULD BE EXPECTED. THE
FRONT IS EXPECTED TO PUSH INTO THE AREA FROM THE WEST LATE IN THE
DAY, SO THERE WILL REMAIN THE POSSIBILITY FOR SHOWERS AND
THUNDERSTORMS THROUGHOUT THE DAY. THE SPC HAS THE EASTERN HALF OF
THE CWA OUTLINED IN A SLIGHT RISK, BUT AS THEY MENTIONED, A
LIMITING FACTOR IN THE POSSIBILITY OF SEVERE WEATHER WILL BE THE
AMOUNT OF CLOUDS AND RAINFALL TO START THE DAY. HOWEVER, THERE
REMAINS INSTABILITY AND SHEAR ACROSS THE AREA, AND IF ANY STORM
CAN PUNCH THROUGH THE LOW-LEVEL CAP, WE COULD GET SOME ISOLATED
STRONG TO SEVERE STORMS.
DAYTIME HIGHS WERE A BLEND DO THE MAV/MET MOS AS THEY WERE IN
GOOD AGREEMENT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
500MB: A NOTABLE -2 STANDARD DEVIATION (SD) TROUGH FROM SOUTHEAST
CANADA INTO THE EASTERN GREAT LAKES TO START THE PERIOD WILL
SLOWLY WEAKEN LATE IN THE WEEK AS A NEW -1SD TROUGH EVOLVES OVER
THE LOWER MISSISSIPPI VALLEY THIS COMING WEEKEND. THAT TROUGH
WEAKENS A BIT IN ITS EASTWARD DRIFT TOWARD THE APPALACHIANS EARLY
NEXT WEEK.
TEMPERATURES: THE FIRST 11 DAYS OF THE MONTH HAVE AVERAGED
GENERALLY 1 TO 3 DEGREES BELOW NORMAL AND WILL CONTINUE TO DO SO
OVER THE COURSE OF THIS FORECAST PERIOD. THE CALENDER DAY AVERAGE
SHOULD BE ABOUT 3 TO 5 DEGREES BELOW NORMAL WEDNESDAY AND
FRIDAY... 6 TO 8 DEGREES BELOW NORMAL FOR THURSDAY-DELIGHTFUL FOR
SUMMER IN OUR AREA... THEN STILL SLIGHTLY BELOW NORMAL SATURDAY
WITH NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES SUNDAY AND MONDAY.
WHILE OUT OF OUR FORECAST RANGE...THE NAEFS IS FINALLY OUTLOOKING
ODDS FAVORING ABOVE NORMAL TEMPERATURES TO DEVELOP IN OUR AREA
NEXT WEEK AS 500 MB HEIGHTS RISE IN THE NORTHERN UNITED STATES.
THE DAILIES BELOW...
TUESDAY NIGHT...WHATEVER LEFTOVER SHOWERS AND ISOLATED TSTMS
DURING THE EVENING SHOULD END BY MIDNIGHT...FOLLOWED BY CLEARING.
PATCHY FOG AND STRATUS POSSIBLE LATE.
CONFIDENCE ON ANY RAIN BEYOND 8 PM TUESDAY EVENING IS BELOW
AVERAGE. ITS A CHANCE BUT ONLY A SMALL CHANCE AND IT COULD VERY
EASILY BE DRY. 50 50 12Z/12 GFS/NAM MOS BLEND. PWAT DECREASES
CONSIDERABLY DURING THE NIGHT AS IT DRIES OUT ALOFT...LOSS OF AT
LEAST 3/4 INCH PWAT.
WEDNESDAY...VERY NICE DRY WX WITH PWAT GENERALLY UNDER .75 INCHES
AND A NW SFC WIND GUSTY 15 TO 25 MPH. PARTLY-MOSTLY SUNNY DAY
FOLLOWED BY A CLEAR NIGHT. 50 50 BLENDED 12Z/12 GFS/NAM MOS
GUIDANCE. THE FCST TEMPS MAY BE 2-3 DEGREES TOO WARM WEDNESDAY.
CONFIDENCE ON THE OVERALL FCST: HIGH.
THURSDAY...DELIGHTFUL WEATHER AS HIGH PRESSURE SPREADS ACROSS THE
REGION. LIGHT WIND WITH AFTN SEA BREEZES ALONG THE COASTS. PWAT .6
INCHES. 12Z/12 MEX GUIDANCE WAS BLENDED 50 50 WITH THE PREVIOUSLY
COOLER PHI FCST FROM EARLY THIS MORNING. THE 12Z GFS MEXMOS LOOKS
TOO WARM BY SEVERAL DEGREES ON THURSDAY. EVEN THE FCST LOOKS LIKE
IT MIGHT BE A DEGREE OR TWO ON THE WARM SIDE. NO MATTER...OVERALL
FORECAST SCENARIO CONFIDENCE IS HIGH.
FRIDAY-MONDAY...1522Z HPC GUIDE BLENDED 50 50 AT TIMES WITH THE
12Z/12 GFS MEX GUIDANCE.
FRIDAY AND SATURDAY...FAIR WX FRIDAY THROUGH SATURDAY AS SFC HIGH
PRESSURE IS CURRENTLY MODELED TO BE RIDGED E-W NEAR 42 DEGREES N
LATITUDE...OR JUST N OF OUR AREA. CONFIDENCE AVERAGE.
SUNDAY INTO MONDAY...INCREASING PWAT N OF THE SFC WARM FRONT
ALONG WITH A DEVELOPING E-NE SFC WIND GUSTY 15 -20 MPH AT TIMES.
SHOWERS...SOME HEAVY...SHOULD DEVELOP DELMARVA SUNDAY AND SLIDE
NEWD THROUGH S NJ SUNDAY NIGHT AND MONDAY. ODDS FOR SHOWERS ARE
MOST FAVORED ALONG AND SE OF THE I95 CORRIDOR. CONFIDENCE BELOW
AVERAGE.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
MAINLY VFR CONDITIONS ARE ANTICIPATED UNTIL ABOUT 0700Z OR 0800Z.
THE ONLY EXCEPTION MAY BE SOME LIGHT FOG DEVELOPING AT OUR MORE
SUSCEPTIBLE TAF SITES LIKE KMIV AND KRDG.
AFTER 0700Z OR 0800Z, CONDITIONS ARE EXPECTED TO DETERIORATE IN
OUR REGION AS AN AREA OF SHOWERS AND SCATTERED THUNDERSTORMS
ARRIVES FROM THE WEST. THE RAIN MAY BE MODERATE TO HEAVY AT TIMES
ON TUESDAY MORNING CAUSING CONDITIONS TO DROP INTO THE IFR RANGE.
THE MAIN AREA OF PRECIPITATION IS FORECAST TO PASS TO OUR EAST AND
NORTHEAST ON TUESDAY AFTERNOON. HOWEVER, LINGERING SHOWERS AND
THUNDERSTORMS ARE POSSIBLE.
THE WIND IS FORECAST TO BE 6 KNOTS OR LESS OVERNIGHT AND ON
TUESDAY MORNING. IF IT FAVORS ANY DIRECTIONS THEY WILL BE SOUTH
AND SOUTHEAST. THE WIND IS EXPECTED TO BECOME WESTERLY FOR
TUESDAY AFTERNOON WITH SPEEDS INCREASING TO 8 TO 10 KNOTS.'
OUTLOOK...
TUESDAY NIGHT...VFR WITH A CHANCE OF BRIEF MVFR OR IFR CONDS IN
ANY LEFTOVER SHOWERS/TSTMS AND IN ANY PATCHES OF ST/FOG.
CONFIDENCE: AVERAGE.
WED THRU SAT...MOSTLY VFR EXPECTED. NW WIND GUST 15-20 KT
WEDNESDAY OTRW GENERALLY LIGHT WIND THU-SAT WITH COASTAL SEA
BREEZES. PRIMARILY DIURNAL DRIVEN AFTN SCT-BKN CLOUDS AOA 5000 FT.
CONFIDENCE: ABOVE AVERAGE.
&&
.MARINE...
SUB-ADVISORY CONDITIONS ARE EXPECTED TO REMAIN ACROSS THE COASTAL
WATERS FOR TONIGHT INTO TUESDAY, ALTHOUGH WINDS MAY GUST AROUND 20
KNOTS AHEAD OF AN APPROACHING COLD FRONT ON TUESDAY. A PERIOD OF
HEAVY RAIN AND POSSIBLE THUNDERSTORMS IS EXPECTED TO OCCUR
TUESDAY AHEAD OF THE COLD FRONT. LOCALLY GUSTY WINDS ARE POSSIBLE
WITH ANY SHOWERS/THUNDERSTORMS.
OUTLOOK...
OVERALL TUESDAY NIGHT THROUGH SATURDAY...SUB-SCA CONDITIONS
THROUGH THE PERIOD.
THE NW WIND MAY BRIEFLY GUST 20-23 KT WEDNESDAY AND THERE IS
SMALL CHANCE WE'LL NEED AN SCA FOR A PORTION OF THE DAYLIGHT HOURS
WEDNESDAY BUT FOR NOW WIND GUSTS HAVE BEEN CAPPED AT 22 KT.
IN ESSENCE...OVERALL VERY GOOD FISHING WEATHER MOST DAYS ON
RELATIVELY QUIET SEAS THIS WEEK.
&&
.RIP CURRENTS...
THE QUIET ATLANTIC BASIN TROPICS SO FAR THIS SEASON HAS RESULTED
IN GENERALLY DAILY LOW RISKS FOR THE FORMATION OF TRANSITORY RIP
CURRENTS ALONG THE NJ DE ATLANTIC BEACHES. THIS PATTERN IS
OUTLOOKED TO CONTINUE THIS WEEK WITH LOW RISK PROJECTED THROUGH AT
LEAST FRIDAY.
ITS POSSIBLE THAT FOR A DAY NEXT WEEKEND...THE PERSISTENT
EASTERLY FLOW MIGHT BUILD UP A 4 FT 7 SECOND EASTERLY SWELL AND IF
THE EASTERLY WIND IS STRONG ENOUGH...THIS COULD LEAD TO A MODERATE
RISK FOR THE FORMATION OF RIP CURRENTS. EVEN THIS IS IN DOUBT
SINCE THE GFS WW3 TENDS TO OVER FORECAST THE SWELLS WHEN THE
ATLANTIC BASIN IS QUIET.
A REMINDER: LOW RISK DOES NOT MEAN NO RISK! FOR GREATEST SURF
ZONE SAFETY...SWIM IN THE PRESENCE OF LIFEGUARDS AND NEVER ALONG
PIERS AND JETTIES WHERE RIP CURRENTS ARE KNOW TO CONSTANTLY RECUR.
&&
.EQUIPMENT...
FOR THOSE WHO USE THE GFS ETSS WEB SITE: IT IS OTS AND ITS TIME
OF RTS IS UNKNOWN. THE PROBLEM IS BEING WORKED ON.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DRAG
NEAR TERM...IOVINO
SHORT TERM...ROBERTSON
LONG TERM...DRAG
AVIATION...DRAG/IOVINO
MARINE...DRAG/ROBERTSON
RIP CURRENTS...DRAG
EQUIPMENT...DRAG