518
FXUS61 KPHI 200640
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
140 AM EST THU FEB 20 2025
SYNOPSIS
AN AREA OF LOW PRESSURE TRACKS NORTHEASTWARD AND OUT TO SEA
TODAY AND TONIGHT. HIGH PRESSURE WILL BUILD IN LATER FRIDAY
INTO SATURDAY, THEN LOW PRESSURE TRACKS ACROSS THE GREAT LAKES
REGION EARLY NEXT WEEK WITH A WEAK COLD FRONT APPROACHING OUR
AREA.
NEAR TERM /THROUGH TONIGHT/
SURFACE LOW PRESSURE JUST EAST OF CAPE HATTERAS EARLY THIS
MORNING WILL TRACK NORTHEASTWARD OUT TO SEA THROUGH TODAY AND
TONIGHT. MEANWHILE, SURFACE HIGH PRESSURE CENTERED OVER THE
NORTH-CENTRAL GREAT PLAINS WILL EVER SO SLOWLY BUILD EASTWARD
BEHIND IT, ENDING UP CENTERED NEAR THE LOWER OHIO VALLEY BY LATE
FRIDAY. ALOFT, A CLOSED LOW LOCATED OVER THE SOUTHERN GREAT
LAKES WILL HEAD GENERALLY EAST TO EAST-SOUTHEASTWARD TODAY,
CROSSING OUR REGION THIS EVENING BEFORE IT TOO HEADS OUT TO SEA
LATE TONIGHT AND FRIDAY.
ARCTIC AIR MASS PRESENTLY IN PLACE IS KEEPING THE REGION COLD
FOR THE MOMENT, WITH TEMPS IN MANY AREAS LIKELY DEEP INTO THE
TEENS AGAIN EARLY THIS MORNING, AND SOME SPOTS IN THE POCONOS
DOWN IN THE SINGLE DIGITS TO START THE DAY. THE COASTAL LOWS
EFFECTS WILL NOW BE PRIMARILY PRESSURE GRADIENT RELATED AS WINDS
WILL SLOWLY BUT SURELY INCREASE THROUGH TODAY AND TONIGHT AS THE
SYSTEM STRENGTHENS OFFSHORE. MEANWHILE, FORCING WITH THE
APPROACHING CLOSED UPPER LOW WILL INCREASE THROUGH THE DAY,
LIKELY LEADING TO INCREASING CLOUDS THIS MORNING AND THEN SNOW
SHOWERS BREAKING OUT BY THIS AFTERNOON, WHICH WILL KEEP HIGHS
TODAY BELOW FREEZING FOR NEARLY EVERYONE. OVERALL, CONSISTENCY
IMPROVED WITH GUIDANCE ON THIS FEATURE OVERNIGHT, SO NUDGED POPS
UP A BIT, BUT STILL MOSTLY IN THE CHANCE TO HIGH- CHANCE RANGE.
IN THE NORTHERN AREAS, ESPECIALLY THE POCONOS, WENT LIKELY
GIVEN THE OROGRAPHIC ENHANCEMENT AND THE FAVORABLE TRACK OF THE
UPPER LOW JUST TO THE SOUTH, PROMOTING THE BEST CHANCE OF
SNOWFALL THERE. THAT HAVING BEEN SAID, EVEN THERE, WE'RE NOT
LOOKING AT MORE THAN AN INCH OR TWO, AND FOR THE VAST MAJORITY
OF THE REGION, ACCUMULATIONS TODAY INTO THIS EVENING SHOULD BE
LESS THAN AN INCH. THAT SAID, WITH COLD TEMPS, ROADS COULD GET
SLIPPERY ESPECIALLY AFTER SUNSET THIS EVENING, SO ANYONE WITH
PLANS TO BE OUT AND ABOUT SHOULD USE CAUTION AND ALLOW EXTRA
TIME.
ONCE THE UPPER LOW PASSES THIS EVENING, SKIES SHOULD CLEAR AND
THE WIND WILL BECOME THE MAIN STORY, WHICH SHOULD KEEP TEMPS A
LITTLE LESS COLD TONIGHT COMPARED TO THIS MORNING. WINDS PEAK
FRIDAY WITH GUSTS POSSIBLY REACHING 40 MPH. HOWEVER, THE
INCOMING AIR MASS IS ACTUALLY LESS SEVERE, SO TEMPS SHOULD
MODERATE AND HIGHS SHOULD GET ABOVE FREEZING FOR MANY UNDER
SUNNY TO PARTLY CLOUDY SKIES.
SHORT TERM /FRIDAY THROUGH SATURDAY/
SURFACE HIGH PRESSURE REMAINS IN CONTROL OF THE WEATHER ACROSS
THE MIDDLE ATLANTIC THRU THIS PERIOD. MEANWHILE THE UPPER AIR
PATTERN DEAMPLIFIES SOMEWHAT, SO MODERATION OF THE RECENT COLD
TEMPS CAN BE EXPECTED. ONE LAST, FRIGID NIGHT FRIDAY NIGHT/SAT
MORNING WITH LOWS IN THE TEENS FAR N/W AND LOW 20S FOR DELMARVA
AND METRO PHILADELPHIA AREAS. FOLLOWING THAT, HIGHS SATURDAY
WILL POP BACK TO THE UPPER 30S N/W AND LOW 40S MOST OTHER AREAS.
STILL A COUPLE DEGREES BELOW NORMAL, BUT 10 TO 12 DEGREES
WARMER THAN TODAY. ALONG WITH THE HIGH PRESSURE, MOSTLY CLEAR
SKIES MUCH OF THE TIME. WINDS WILL BE LIGHT MUCH OF THE TIME.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
OVERVIEW: THE UPPER PATTERN FOR THE END OF THE WEEKEND AND INTO
NEXT WEEK WILL FEATURE A RIDGE ACROSS THE WESTERN U.S. WHILE A
TROUGH REMAIN ACROSS THE EAST. AS THE WEEK CONTINUES, THE RIDGE
WILL STRENGTHEN WHILE THE TROUGH BECOMES DEEPER. OVERALL, DRY
WITH MILDER TEMPS EARLY IN THE WEEK AND COLDER AIR LATE.
AFTER A PERIOD OF FROSTY WINTRY READINGS FOR MUCH OF MID-
FEBRUARY, TEMPERATURES BACK NEAR NORMAL ARE EXPECTED SUNDAY.
NORMALS FOR THIS TIME OF YEAR ARE IN THE MID 40S FOR THE
DELAWARE VALLEY AND SOUTH NJ WHILE READINGS UP NORTH ARE
NORMALLY IN THE MID/UPPER 30S FOR MOUNT POCONO AND SUSSEX COUNTY
NJ. SOUTHERN DELAWARE HAS AVERAGE HIGHS CLOSE TO 50 DEGREES.
TEMPERATURES DURING THE LONG TERM WILL FEATURE TEMPERATURES BACK
TO NORMAL OR A LITTLE ABOVE WITH THE UPPER TROUGH RELAXING
ACROSS THE MIDDLE ALTANTIC AND NORTHEAST. HIGH TEMPS ARE
CURRENTLY FORECASTED TO GO INTO THE UPPER 40S OR LOW 50S,
PERHAPS SOME MID 50S ACROSS THE REGION EARLY NEXT WEEK. THE MILD
READINGS SHOULD COULD HOLD IN TO WEEKS END WHEN MORE COLD AIR
LOOMS OFF IN THE DISTANCE.
THERE IS NOT MUCH OPPORTUNITY FOR SIGNIFICANT PRECIPITATION
DURING THE LONG TERM. THE MODERATING AIR MASS/PATTER
SUNDAY/MONDAY WILL STEER A WEAK CLIPPER-TYPE SYSTEM NORTH OF THE
REGION LATER MONDAY AND INTO TUESDAY. WE HAVE SOME NBM POPS,
MOSTLY SLIGHT CHC BUT CHC ACROSS THE NORTH FOR THOSE PERIODS.
P-TYPE WILL FAVOR SNOW NORTH AND RAIN SOUTH. TIME OF DAY WILL
PLAY INTO THE P-TYPE FACTOR WHEN THE TIME NEARS. OVERALL, LIGHT
TOTALS ARE EXPECTED ATTM.
AVIATION /07Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
VFR THRU EARLY THIS MORNING WITH NW WINDS 5-15 KTS. WINDS
INCREASE AS THE DAY WEARS ON, REACHING 10-20 KTS WITH GUSTS
APPROACHING 30 KTS LATE TODAY. MORE IMPORTANTLY, HOWEVER, BAND
OF SNOW/SNOW SHOWERS MAY RESULT IN INTERVALS OF IFR CONDITIONS
MAINLY FROM KPHL ON NORTH DURING THE AFTERNOON, POSSIBLY
EXTENDING INTO THE EVENING. FOR NOW HAVE INSERTED IFR TEMPOS FOR
NORTHERN TERMINALS AND MVFR TEMPOS FURTHER SOUTH, BUT THESE WILL
SURELY NEED REFINEMENT.
CONDITIONS IMPROVE TO VFR AFTER ANY LINGERING SNOW ENDS THIS
EVENING AND STAY VFR THRU FRIDAY. WINDS WILL REMAIN GUSTY FROM
THE NW, 10-20 KTS WITH GUSTS TO 30 KTS THRU THE PERIOD, POSSIBLY
TOPPING 35 KTS ON FRIDAY.
OUTLOOK...
SATURDAY THROUGH MONDAY...VFR.
MARINE
NO HEADLINES PRESENTLY, BUT WITH COASTAL LOW STRENGTHENING AS IT
HEADS EAST OF US TODAY THRU FRIDAY, EXPECT WINDS TO REALLY RAMP
UP. SCA STARTS AT DAWN TODAY, THOUGH MAY TAKE A FEW HOURS TO GET
GOING, ESPECIALLY IN THE NORTHERN WATERS. MEANWHILE, GALES NOW
LOOK LIKELY FOR ALL WATERS TONIGHT INTO FRIDAY, SO HOISTED GALES
FOR BOTH PERIODS FOR ALL WATERS. PERIODS OF SNOW OR SNOW SHOWERS
MAY ALSO IMPACT NAVIGATION, ESPECIALLY THIS AFTERNOON AND
EVENING.
OUTLOOK...
FRIDAY NIGHT...WINDS AND SEAS DIMINISH OVERNIGHT. SCA FLAG INTO
THE EVENING MAY BE NEEDED. FAIR WEATHER.
SATURDAY THROUGH MONDAY...SUB-SCA EXPECTED. FAIR WEATHER.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS
EVENING FOR ANZ430-431-450>455.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EST FRIDAY FOR
ANZ430-431-450>455.
SYNOPSIS...GORSE/RCM
NEAR TERM...RCM
SHORT TERM...OHARA
LONG TERM...OHARA
AVIATION...OHARA/RCM
MARINE...OHARA/RCM
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