948
FXUS61 KPHI 122029
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
329 PM EST TUE NOV 12 2024
SYNOPSIS
HIGH PRESSURE REMAINS IN CONTROL THROUGH THURSDAY. A WEAK LOW WILL
APPROACH THE REGION ON THURSDAY NIGHT WITH A COASTAL LOW DEVELOPING
TO OUR SOUTH WHICH WILL MOVE OUT TO SEA ON FRIDAY. HIGH PRESSURE
RETURNS FOR THE WEEKEND AHEAD OF A COLD FRONT THAT APPROACHES THE
REGION EARLY NEXT WEEK.
NEAR TERM /THROUGH WEDNESDAY/
GUSTY NNW WINDS UPWARDS OF 25-35 MPH PERSIST THIS AFTERNOON, HELPING
USHER IN A COLD AIRMASS INTO THE REGION FOR TONIGHT.
HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH TONIGHT AND
INTO WEDNESDAY. WINDS WILL GRADUALLY DIMINISH OVERNIGHT, BUT LIKELY
REMAIN A BIT BREEZY THROUGH MIDNIGHT WITH GUSTS REMAINING AROUND 20
MPH UNTIL THEN. COLD AIR WILL FILTER IN AT THIS POINT WITH LOWS
EXPECTED TO DROP IN TO THE MID 20S TO LOW 30S, PLACING MUCH OF THE
REGION BELOW FREEZING WITH THE EXCEPTION OF THE IMMEDIATE COAST
STAYING IN THE MID-30S.
ANOTHER DRY AND COOL DAY WEDNESDAY WITH SUNNY SKIES AND AFTERNOON
HIGHS ONLY REACHING THE UPPER 40S TO LOW 50S. A VERY DRY AIRMASS
WILL BE IN PLACE AT THIS POINT WITH MINIMUM RH VALUES DROPPING TO 20-
30% ACROSS MOST LOCATIONS, BUT WINDS ARE EXPECTED TO BE MUCH LOWER
WITH NORTHERLY WINDS GUSTING TO AROUND 10-15 MPH. GIVEN THE DRY
AIRMASS, FIRE WEATHER RISK WILL REMAIN ELEVATED WEDNESDAY. SEE FIRE
WEATHER SECTION BELOW.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
THE WEDNESDAY NIGHT AND THURSDAY PERIOD WILL FEATURE TRANQUIL AND
SEASONABLY COOL WEATHER OVERALL, AS STRONG HIGH PRESSURE SLOWLY
SHIFTS EAST ACROSS SOUTHERN CANADA. CLOUDS WILL GRADUALLY INCREASE
THROUGH THIS TIME AS THE NEXT WEATHER SYSTEM APPROACHES FROM THE
MIDWEST. LOWS ON WEDNESDAY NIGHT WILL MAINLY BE IN THE MID 20S TO
MID 30S WITH HIGHS ON THURSDAY IN THE 40S AND 50S.
ATTENTION THEN TURNS TO THE THURSDAY NIGHT INTO FRIDAY PERIOD AS A
DECAYING TROUGH AND WEAKENING SURFACE LOW MOVES TOWARD THE AREA. THE
SURFACE LOW IS FORECAST TO TRACK INTO THE EASTERN GREAT LAKES BEFORE
TRANSLATING ITS ENERGY TO A DEVELOPING SECONDARY COASTAL LOW OFF THE
COAST OFF THE CAROLINAS. THIS LOW WILL THEN MOVE OUT TO SEA WITHOUT
POSING MUCH OF A THREAT TO THE MID-ATLANTIC. SO AS THIS INITIAL LOW
APPROACHES, RAIN SHOWERS ARE EXPECTED TO MOVE INTO OUR AREA,
ESPECIALLY SOUTH AND WEST OF PHILADELPHIA (WHERE POPS ARE UP TO 40-
60%). TO THE NORTH AND EAST OF PHILADELPHIA, THE STRONG HIGH
PRESSURE OVER CANADA SHOULD CAUSE A SHARP MOISTURE GRADIENT, SO
THESE LOCATIONS MAY SEE A FEW ISOLATED SHOWERS TO NOTHING AT ALL. IN
TERMS OF QPF, GENERALLY LOOKING AT 0.10-0.25" SOUTH AND WEST OF
PHILLY, WITH LESS THAN 0.10" NORTH AND EAST OF PHILLY. SURPRISINGLY,
THIS SET-UP DOES APPEAR TO BE A COLD AIR DAMMING SET-UP, MAINLY IN
THE POCONO REGION, SO WOULDN'T BE SURPRISED IF THERE IS A SHORT
PERIOD OF FROZEN PRECIP ON THURSDAY NIGHT IF ANY PRECIP IS TO MAKE
IT INTO THESE AREAS. LOWS WILL MAINLY BE IN THE 30S/40S.
ANY SHOWERS WILL THEN TAPER OFF FROM NORTH TO SOUTH EARLY ON FRIDAY
WITH CLEARING SKIES BY THE AFTERNOON AS HIGH PRESSURE BUILDS BACK IN
FROM THE WEST. HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL MAINLY
IN THE UPPER 40S TO MID 50S.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
HEADING INTO NEXT WEEKEND, UPPER LEVEL RIDGING IS FORECAST TO BUILD
AS AN EXPANSIVE AREA OF HIGH PRESSURE APPROACHES FROM THE WEST. THIS
WILL RESULT IN A DRY WEEKEND WITH TEMPERATURES RETURNING TO ABOVE
NORMAL STANDARDS. IT MAY BE BREEZY AT TIMES OVER THE WEEKEND HOWEVER
AND WITH DRY NORTHWESTERLY FLOW, THIS COULD SPARK AN ADDITIONAL
ROUND FOR SOME FIRE WEATHER CONCERNS...HOWEVER ITS TOO FAR IN
ADVANCE TO NARROW DOWN SPECIFICS.
BY EARLY NEXT WEEK, A SHORTWAVE TROUGH WILL APPROACH THE REGION WITH
A SURFACE COLD FRONT. CURRENT TIMING AT THIS POINT APPEARS TO BE ON
MONDAY WHERE A FEW RAIN SHOWERS MAY BE POSSIBLE WITH THE FRONT. HIGH
PRESSURE THEN RETURNS FOR TUESDAY AS TEMPERATURES STILL REMAIN A FEW
DEGREES ABOVE NORMAL.
AVIATION /21Z TUESDAY THROUGH SUNDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. NORTHWEST WINDS GUSTING UP TO 30 KT DURING THE
DAY TIME HOURS. HIGH CONFIDENCE.
TONIGHT...VFR CONDITIONS EXPECTED. WIND SPEEDS SHOULD DROP OFF
QUICKLY AROUND 04-05Z, REMAINING NEAR 10 KT FOR MUCH OF THE NIGHT.
WEDNESDAY...VFR. NORTH WINDS AROUND 5-10 KT.
OUTLOOK...
WEDNESDAY NIGHT...VFR WITH INCREASING CLOUDS. NO SIGNIFICANT WEATHER
EXPECTED.
THURSDAY THROUGH THURSDAY NIGHT...MAINLY VFR. SUB-VFR CONDITIONS
POSSIBLE ON THURSDAY NIGHT WITH A CHANCE OF RAIN SHOWERS.
FRIDAY THROUGH SATURDAY...VFR. NO SIGNIFICANT WEATHER EXPECTED.
MARINE
SMALL CRAFT ADVISORY IN EFFECT FOR THE ENTIRE MARINE AREA. NNW WINDS
REMAIN GUSTY AROUND 30 KT LATE THIS AFTERNOON WITH SEAS 4-7 FEET,
EXPECTING WINDS TO GRADUALLY DIMINISH TONIGHT. UPPER AND LOWER
DELAWARE BAY WILL SEE WINDS FALL BELOW ADVISORY CRITERIA OVERNIGHT
WITH THE REMAINING COASTAL MARINE ZONES SEEING LINGERING SEAS 3-5
FEET THROUGH THE AFTERNOON.
OUTLOOK...
WEDNESDAY NIGHT THROUGH FRIDAY...SMALL CRAFT ADVISORY CONDITIONS ON
THE ATLANTIC OCEAN COASTAL WATERS ARE POSSIBLE MAINLY DUE TO SEAS
HOVERING AROUND 5 FEET.
FRIDAY NIGHT THROUGH SATURDAY...SMALL CRAFT ADVISORY CONDITIONS
LIKELY DUE TO WINDS AROUND 25-30 KT AND SEAS AROUND 5 FEET.
FIRE WEATHER
GUSTY WINDS CONTINUE THROUGH TUESDAY EVENING WITH GUSTS OVER 20 MPH.
FOR WEDNESDAY, DRY CONDITIONS ARE EXPECTED TO CONTINUE. WINDS WILL
GENERALLY BE NEAR 5-10 MPH WITH A FEW GUSTS UP TO 15 MPH, MUCH LOWER
THAN THE DAY BEFORE. A VERY DRY AIRMASS WILL BE IN PLACE
HOWEVER WITH MINIMUM RH VALUES WILL FALLING INTO THE 20-30% RANGE.
RH VALUES DO RECOVER THURSDAY WITH A CHANCE OF SHOWERS IN THE
AFTERNOON AND EVENING. BEST CHANCE FOR RAINFALL WILL BE SOUTH AND
WEST OF THE PHILADELPHIA METRO WITH MINIMAL RAINFALL NORTH AND EAST.
LOOKING FARTHER AHEAD, RH VALUES REMAIN IN THE 30-40% RANGE FOR
FRIDAY AND INTO THE WEEKEND ALONG WITH SOME BREEZY CONDITIONS.
TIDES/COASTAL FLOODING
A COMBINATION OF PERSISTENT SHORE PARALLEL WINDS AND INCREASING
ASTRONOMICAL TIDES WITH A FULL MOON ON FRIDAY LOOK TO LEAD TO
SOME COASTAL FLOODING CONCERNS FOR THE BACK HALF OF THIS WEEK.
THE MOST LIKELY LOCATIONS TO BE IMPACTED BY TIDAL FLOODING WOULD
BE ALONG THE ATLANTIC OCEAN COASTS OF NEW JERSEY AND DELAWARE
AND THE ASSOCIATED BACKBAYS.
SPOTTY MINOR TIDAL FLOODING MAY OCCUR AS EARLY AS THE WEDNESDAY
MORNING HIGH TIDE BUT ANY WIDESPREAD TIDAL FLOODING IS FORECAST
TO HOLD OFF UNTIL THE THURSDAY MORNING HIGH TIDE. SOME OF THE
GUIDANCE SUGGESTS THE POTENTIAL FOR MODERATE TIDAL FLOODING
TOWARDS THE END OF THE WEEK ALONG THE ATLANTIC COASTLINE. FURTHER
UPDATES WITH GREATER SPECIFICITY IN THE TIMING AND EXTENT OF
ANY IMPACTS WILL COME AS UNCERTAINTY DECREASES.
COASTAL FLOODING IS NOT EXPECTED TO OCCUR ALONG THE CHESAPEAKE
BAY IN THE EASTERN SHORE OF MARYLAND AND ALONG THE TIDAL
DELAWARE RIVER.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ430-431.
SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR ANZ450.
SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ451>455.
SYNOPSIS...DESILVA/HOEFLICH
NEAR TERM...MJL
SHORT TERM...DESILVA
LONG TERM...DESILVA/HOEFLICH
AVIATION...DESILVA/MJL
MARINE...DESILVA/MJL
FIRE WEATHER...WFO PHI
TIDES/COASTAL FLOODING...WFO PHI
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page