NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Apr 22, 8:34 AM EST, 5 hours 25 minutes earlier.
Area forecast discussion, Apr 22, 8:34 AM EST, 5 hours 25 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
934 AM EDT WED APR 22 2015
.SYNOPSIS...
A COLD FRONT WILL CROSS THE FORECAST AREA THIS AFTERNOON WITH
A WEAKER COLD FRONT FOLLOWING ON THURSDAY. A LOW PRESSURE
SYSTEM IS EXPECTED TO CUT ACROSS THE TENNESSEE VALLEY AND
THE CAROLINAS SATURDAY INTO SATURDAY NIGHT. A HIGH PRESSURE
SYSTEM WILL GRADUALLY BUILD IN FROM THE WEST ON SUNDAY AND REACH
THE APPALACHIANS BEFORE WEAKENING ON MONDAY. A STRONG LOW PRESSURE
SYSTEM IS PREDICTED TO START ORGANIZING IN THE CENTRAL UNITED
STATES ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
930 AM UPDATE...NO MAJOR CHANGES WITH THE FORECAST. COLD FRONT IS
SLOWLY TRUDGING THROUGH CENTRAL PA AT THIS TIME. SHOWERS HAVE
BECOME WIDESPREAD AND THERE HAVE BEEN A FEW LIGHTNING STRIKES OVER
SOUTHWESTERN PA AND NORTHERN WV.
PREVIOUS NEAR TERM DISCUSSION...AN AREA OF LOW PRESSURE WILL
SLOWLY PINWHEEL AROUND IN SOUTHEAST CANADA THROUGH TODAY, BRINGING
A COLD FRONT ACROSS THE AREA LATER THIS AFTERNOON. MOSTLY
SUNNY/PARTLY CLOUDY SKIES WILL BEGIN TO DAY TODAY, BUT CLOUD COVER
WILL BE ON THE INCREASE AHEAD OF AN APPROACHING COLD FRONT. THERE
ARE SOME SCATTERED SHOWERS TO OUR WEST EARLY THIS MORNING AS THERE
IS SOME WEAK VORTICITY IMPULSES SLIDING THROUGH PENNSYLVANIA.
THESE SCATTERED SHOWERS WILL CONTINUE THROUGH THE MORNING, BUT
MORE WIDESPREAD ACTIVITY IS EXPECTED TO DEVELOP TO OUR WEST LATER
THIS MORNING INTO THIS AFTERNOON ALONG AND AHEAD OF THE
APPROACHING COLD FRONT. INSTABILITY IS FORECAST TO INCREASE ACROSS
THE AREA DURING THE DAY WITH CAPE VALUES AROUND 200-300 J/KG AND
SLIGHTLY NEGATIVE LI'S, SO THERE COULD BE SOME THUNDERSTORMS
DEVELOP AS THE LINE OF SHOWERS MOVES EASTWARD. IF ANY
THUNDERSTORMS DO DEVELOP, THEY COULD PRODUCE STRONG GUSTY WINDS,
OR EVEN SMALL HAIL WITH THE FREEZING LEVEL BEING PRETTY LOW.
AS WE BEGIN TO WARM THIS MORNING AFTER THE SUN COMES UP, STRONG
MIXING WILL BEGIN TO TAKE PLACE ACROSS THE AREA. THIS WILL ALLOW
WINDS ABOVE THE SURFACE TO BEGIN TO MIX DOWN TO THE SURFACE. GUSTY
WINDS ARE EXPECTED TODAY, WITH THE STRONGEST WINDS EXPECTED DURING
THE AFTERNOON, REACHING 30-40 MPH. THERE IS THE POSSIBILITY THAT
EVEN STRONGER WINDS COULD OCCUR WITH THE SHOWERS/THUNDERSTORMS THIS
AFTERNOON AS THEY COULD CARRY STRONGER WINDS DOWN TO THE SURFACE.
&&
.SHORT TERM /THURSDAY/...
THE COLD FRONT AND ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO
BE MAKING THEIR WAY ACROSS THE AREA DURING THE EARLY EVENING HOURS.
THERE COULD REMAIN SOME ISOLATED/SCATTERED SHOWERS BEHIND THE FRONT
INTO THE LATE EVENING HOURS AS THE COLD POOL ALOFT MOVES ACROSS THE
AREA. WE EXPECT ANY SHOWER ACTIVITY TO BE ENDING AROUND OR SHORTLY
AFTER MIDNIGHT AS THE SHORT WAVE MOVES PAST THE AREA. SOME PARTIAL
CLEARING MAY BEGIN TAKING PLACE OVERNIGHT, BUT WE DON'T EXPECT ALL
CLEAR SKIES.
TEMPERATURES OVERNIGHT WILL COOL BEHIND THE COLD FRONT. IT IS
POSSIBLE FOR SOME PATCHY FROST TO DEVELOP ACROSS PORTIONS OF
NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY, BUT SINCE IT IS NOT
EXPECTED TO BE WIDESPREAD SINCE THERE COULD REMAIN A STEADY BREEZE
INTO THE NIGHT, WE HAVE KEPT IT OUT OF THE FORECAST FOR NOW. THE
POCONOS WILL BE THE COLDEST AND MOST LIKELY AREA FOR FROST, BUT
SINCE THE GROWING SEASON HAS NOT STARTED THERE YET, WE DID NOT
ISSUED AN ADVISORY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
NO CHANGE TO THE BLOCKY / -NAO PATTERN IN THE LONG TERM. NOT
MUCH PRECIPITATION IS EXPECTED TO OCCUR THROUGH TUESDAY WITH THE
MAIN IMPACT BEING BLUSTERY AND POSSIBLY FROSTY CONDITIONS AT
THE START OF THE LONG TERM, WITH A SLIGHT EASING/RECOVERY TOWARD
THE LATTER HALF. BEYOND OUR DETERMINISTIC FORECASTS, THE CAN GGEM
AND ECMWF ARE PREDICTING A RATHER STRONG NOR'EASTER. WHILE THE
FIRST NEEDED INGREDIENT (NEGATIVE NAO) IS IN PLACE, ITS PREDICATED
ON IT RELAXING (THE ARCHAMBAULT EFFECT) AS THE SURFACE LOW MAKES
THE TURN ALONG THE COAST. CONTRAST THAT SOLUTION WITH THE
SATURDAY SYSTEM IN WHICH THE TELECONNECTION IS STILL PREDICTED
NEGATIVE. THAT LOW IS EXPECTED TO EXIT STAGE SOUTH. MANY SOUNDING
RUNS TO GO WITH THE FORMER AND FOR NOW WE WILL TAKE ONE LOW AT A
TIME.
BOTH THE GFS AND WRF-NMM INITIALIZED THE CLOSED LOW WELL AT
500MB. WHILE NEAR STREAM LOCALES WERE SOMETIMES 1C WARMER THAN
INITIALIZED, THE CORE OF THE CHILLY AIR ENTERING MINNESOTA WAS
COLDER THAN INITIALIZED.
SPEAKING OF COLDER, A REINFORCING COLD FRONT IS EXPECTED TO MOVE
THROUGH OUR CWA ON THURSDAY. WITH THE HIGH PRESSURE SYSTEM STILL
REMOVED FROM OUR AREA, THE SUBSIDENCE INVERSION IS WELL ABOVE THE
SURFACE. LOOKS LIKE MORE SELF DESTRUCT SUNSHINE THAN WE THOUGHT
YESTERDAY. ALSO WITH THE INVERSION WELL DISPLACED FROM THE
SURFACE, CLOUDS SHOULD GET SOME VERTICAL DEVELOPMENT. WHILE WE ARE
EXPECTED TO BE BETWEEN STRONG SHORT WAVES, THE DEEPER MOISTURE
NORTH COULD SUPPORT SOME SHOWERS. IF THEY DEVELOP FAST ENOUGH ON
THURSDAY MORNING, SNOW SHOWERS MIGHT OCCUR OVER THE HIGHER
TERRAIN. MAX TEMPS WILL BE LOWER THAN TODAY AS WE WILL BE GETTING
DEEPER INTO THE CHILLY AIR MASS. STAT GUIDANCE LOOKS REASONABLE
BASED ON PREDICTED 925MB AND 2M TEMPS. LASTLY IT WILL BE WINDY
AGAIN, BUT WE SHOULD NOT HAVE AS MANY SHOWERS OR HAVE WIDESPREAD
EVAPORATIONAL COOLING ENHANCEMENT TO THE WINDS.
ON THURSDAY NIGHT, WE MIGHT NEED FROST OR FREEZE RELATED HEADLINES
IN PA AND NJ WHERE THE GROWING SEASON HAS STARTED. AS OF TODAY
THIS INCLUDES ALL OF OUR NORTHERN CWA EXCEPT FOR THE POCONOS. THIS
LOOKS MORE ADVECTIVE THAN RADIATIONAL WHICH MAKES THIS AIR MASS
EVEN MORE IMPRESSIVE.
ANOTHER CHILLY DAY ON FRIDAY, BUT HERE THE NAM/WRF IS NOT AS AGGRESSIVE
WITH CONVECTIVE TEMPS BEING REACHED AND EVEN THE GFS HAS LESS
PREDICTED MOISTURE. WE WOULD EXPECT A BROKEN DECK OF CLOUDS TO
STILL FORM BY AFTERNOON, ESPECIALLY THE NORTHERN HALF OF OUR CWA.
MAX TEMPS SHOULD BE SIMILAR TO THURSDAY'S WITH SLIGHTLY WEAKER
WINDS.
WINDS SHOULD FINALLY START DECREASING ON FRIDAY NIGHT AS THE HIGH
PRESSURE SYSTEM NEARS. THAT IS THE GOOD NEWS. THE BAD NEWS IS WITH
A CHILLY AIR MASS IN PLACE THIS MAKES A RADIATIONAL COOLING NIGHT
WITH MORE FROSTY CONDITIONS POSSIBLE, ESPECIALLY IN MORE RURAL
LOCATIONS.
WITH THE SOUTHERN SLIDER SYSTEM ON SATURDAY AND SATURDAY NIGHT, THE
GFS (GOING NORTH) AND ECMWF (NOW AMONG THE MOST SOUTHWARD SUPPRESSED)
HAVE FLIPPED THEIR POSITIONS. THE COMMON THREAD THEY ARE VACILLATING
OVER IS OUR CWA BEING NEAR THE NORTHERN FRINGE OF PCPN CHANCES. WE
KEPT THE LOW CHANCE SOUTH SATURDAY AFTERNOON (SLOWER TIMING) INTO
SATURDAY NIGHT. CLOUDS WOULD KEEP SATURDAY MAX TEMPS FROM REBOUNDING
FURTHER. ON THE FLIP SIDE CLOUDS SHOULD KEEP SATURDAY NIGHT'S MIN TEMPS
HIGHER.
A WEAKENING HIGH PRESSURE SYSTEM IS THEN EXPECTED TO TRY TO REACH OUR
CWA SUNDAY INTO MONDAY. TEMPERATURES SHOULD RETURN CLOSER TO NORMAL
LEVELS WITH OVERALL DRY WEATHER MAINTAINED. BECAUSE OF TIMING AND
INTENSITY ISSUES, WE PUT IN A LOW CHANCE FOR RAIN ON TUESDAY. ALBEIT
A GREATER, NASTIER CHANCE MIGHT POSSIBLY OCCUR LATER IN THE WEEK.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
VFR CONDITIONS ARE EXPECTED FOR MOST OF THE TAF PERIOD. CLOUDS
WILL INCREASE AND LOWER THROUGH THE DAY AHEAD OF AN APPROACHING
COLD FRONT...HOWEVER CEILINGS SHOULD REMAIN VFR. WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS WILL ACCOMPANY THE FRONT.
THEREFORE, A BRIEF PERIOD (GENERALLY A 2 TO 3 HOUR WINDOW) OF
MVFR VISIBILITIES ARE POSSIBLE WITH THESE SHOWERS AND STORMS. AT
THIS TIME, THINK KRDG AND KABE SHOULD SEE PRIMARILY SHOWERS AS
INSTABILITY IS LIMITED FURTHER WEST. FOR THE REST OF THE TAF
SITES, INCLUDING KPHL, KTTN, KPNE, KILG, KMIV, AND KACY, THERE
IS A HIGH ENOUGH RISK OF TSRA TO INCLUDE THAT MENTION IN THE
TAFS.
WINDS WILL INCREASE LATER THIS MORNING OUT OF THE SOUTHWEST, AND
COULD GUST AROUND 30-35 KNOTS BY THIS AFTERNOON. STRONGER WINDS
COULD OCCUR IF THUNDERSTORMS OCCUR AS WELL. THE STRONG WIND GUSTS
WILL BEGIN TO WEAKEN LATE IN THE AFTERNOON INTO THE EVENING, BEFORE
GUSTS DROP OFF OVERNIGHT, ALTHOUGH A STEADY BREEZE SHOULD REMAIN
ACROSS THE AREA.
OUTLOOK...
THURSDAY AND THURSDAY NIGHT...VFR CONDITIONS EXPECTED. WESTERLY WINDS
WILL BECOME GUSTY IN THE MORNING, GUSTS 20 TO 25 KNOTS, THROUGH THE
AFTERNOON BEFORE DIMINISHING IN THE EVENING AND NIGHT.
FRIDAY AND FRIDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED. WESTERLY
WINDS WILL BECOME GUSTY IN THE MORNING, GUSTS UP TO 20 KNOTS,
THROUGH THE AFTERNOON BEFORE DIMINISHING IN THE EVENING.
SATURDAY AND SATURDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED.
SOME SHOWERS POSSIBLE FROM KPHL AND TO THE SOUTH AND EAST.
SUNDAY...MAINLY VFR CONDITIONS EXPECTED.
&&
.MARINE...
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL OF THE WATERS TODAY.
WINDS ARE EXPECTED TO BEGIN GUSTING 25-30 KNOTS LATER THIS MORNING
INTO THE AFTERNOON AND SEAS ON THE OCEAN WILL BUILD AGAIN TO 5-6
FEET. THERE IS SOME 35-40 KNOT WINDS ABOVE THE SURFACE, BUT WITH THE
COOL WATERS, THE INVERSION IS EXPECTED TO PREVENT THESE STRONG WINDS
FROM MIXING DOWN TO THE SURFACE.
OUTLOOK...
THURSDAY THROUGH FRIDAY...GUSTY WESTERLY WINDS THURSDAY AND
FRIDAY THAT COULD REACH SMALL CRAFT ADVISORY LEVELS. THE
PRESENT SMALL CRAFT ADVISORY APPEARS DESTINED FOR AN EXTENSION
INTO THIS TIME PERIOD.
FRIDAY NIGHT THROUGH SUNDAY...SUB-ADVISORY CONDITIONS ARE
EXPECTED ON THE AREA WATERS. SOME RESIDUAL SMALL CRAFT ADVISORY
CONDITIONS MIGHT OCCUR ON FRIDAY EVENING ON THE OCEAN.
&&
.RIP CURRENTS...
OUR SURF ZONE FORECASTS START FRIDAY THE 15TH OF MAY AND A PNS WAS
ISSUED AROUND 554 PM ANNOUNCING THE NEW BEACH HAZARDS STATEMENT
THAT WILL SUPPLEMENT OUR PRIMARY RIP CURRENT RISK PRODUCTS.
WMO HEADER WHUS41 KPHI
AWIPS ID CFWPHI
THATS THE HEADER
THE PUBLIC INFORMATION STATEMENT EXPLAINS IT ALL.
WE WILL BE ISSUING THE BEACH HAZARDOUS STATEMENT ON AN AS NEEDED
BASIS TO SUPPORT SURF ZONE SAFETY, BUT NO REDUNDANCY WITH OTHER
PRODUCTS. EMPHASIS FOR OUR OFFICE MAY BE ECOLOGICAL (RED TIDE) OR
WIDESPREAD AND ANOMALOUSLY COLDER THAN NORMAL WATERS, POSSIBLY A
RARE SQUALL LINE PRESSURE INDUCED SEICHE. THIS BEACH HAZARD STATEMENT
WILL BE EVOLVING OVER THE COMING YEARS AND WILL CONTAIN INFORMATION
THAT CANNOT BE FOUND IN ANY OTHER MOUNT HOLLY NON-AFD PRODUCT. IT
WILL NOT REPLACE THE PRIMARY METHOD OF INFORMING ABOUT DANGEROUS
RIP CURRENTS, AT LEAST NOT FOR THIS YEAR.
STATEMENTS FROM THIS PROGRAM COULD BEGIN AS EARLY AS THE START OF
OUR MOUNT HOLLY SURF ZONE FORECAST PROGRAM, FRIDAY MAY 15TH BUT
LIKELY BE DELAYED.
THE RECENT COASTAL RESILIENCY WORKSHOP IN VIRGINIA WAS
INFORMATIVE AND CHANGES ARE COMING THE NEXT SEVERAL SEASONS BEYOND
2015. HOPEFULLY THESE CHANGES FURTHER IMPROVE AWARENESS OF THE
RIP CURRENT DANGER. THE OCEAN IS NOT YOUR CALM SWIMMING POOL.
EVENTUALLY PROBABILISTIC TIME OF DAY INFORMATION REGARDING RIP
CURRENT RISK WILL BE DEVELOPED AND VALIDATED BY OBSERVATION. THIS
WILL TAKE INTO ACCOUNT BEACH BATHYMETRY, EVEN AS IT IS CONSTANTLY
ADJUSTING, AS WELL AS TIDAL RELATED TOTAL WATER LEVEL.
THERE WILL NO LONGER BE ANY ASSOCIATION OF RIP CURRENT RISK AND
SWIMMER SKILL. TOO MANY PEOPLE ARE BECOMING VICTIM TO RIP CURRENTS
NO MATTER WHAT SWIMMING SKILL LEVEL, IN LARGE PART DUE TO
SWIMMING AT UNGUARDED BEACHES.
RIP CURRENT AWARENESS WEEK IS JUNE 7-13. MORE TO RIP CURRENT
INFORMATION TO COME HERE AND IN POSSIBLE PUBLIC FORUMS.
REMAINING CALM AND FLOATING IS EXTREMELY IMPORTANT WHEN BEING
SWEPT SEAWARD...THEN ITS AN ATTEMPT TO SWIM OUT OF THESE NARROW
SWIFT CURRENTS OF WATER...PARALLEL TO THE SHORE. RESEARCH IS
DEMONSTRATING THAT MOST OF THESE CURRENTS EVENTUALLY CIRCLE BACK
TOWARD THE SHORE.
SST'S DESPITE THE NEAR RECORD COLD WATERS OF FEBRUARY 20-MARCH 1
HAVE RECOVERED TO NEAR NORMAL AND ACTUALLY ARE WELL ABOVE NORMAL
NOT TOO FAR OFFSHORE, AROUND LONGITUDE 73W.
WE ATTM HAVE NOTHING NEW TO REPORT ON SURF ZONE WAVE RELATED INJURY
RESEARCH BEING CONDUCTED IN DELAWARE.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ430-431-
450>455.
&&
SYNOPSIS...GIGI/MEOLA
NEAR TERM...JOHNSON/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...GIGI
AVIATION...GIGI/JOHNSON/ROBERTSON/MEOLA
MARINE...GIGI/ROBERTSON/MEOLA
RIP CURRENTS...DRAG