700  
FXUS61 KPHI 152058  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
358 PM EST SAT DEC 15 2018  
   
SYNOPSIS
 
 
LOW PRESSURE WILL CONTINUE TO MOVE THROUGH THE AREA  
THROUGH EARLY MONDAY MORNING, BEFORE LIFTING OFF TO THE NORTHEAST. A  
COLD FRONT WILL PASS THROUGH THE REGION MONDAY, USHERING IN COLDER  
AIR. HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY AND WEDNESDAY.  
BY LATE WEEK, ANOTHER EXPANSIVE AREA OF LOW PRESSURE LOOKS TO MOVE  
TOWARD TO THE AREA.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
LIGHT RAIN CONTINUES THIS AFTERNOON OVER THE SOUTHERN PART OF OUR  
FORECAST AREA - GENERALLY PHILLY SOUTHWARD - WHILE NORTHERN AREAS  
REMAIN CLOUDY BUT RAIN FREE. WITH THE UPPER LOW NOW OVER THE TN  
VALLEY, SW FLOW ALOFT CONTINUES BRING MOISTURE INTO OUR ARE, WHILE  
NE WINDS AT THE SURFACE ARE MAINTAINING NEAR STEADY TEMPS AND  
DEWPTS.  
 
FOR TONIGHT, ELONGATED EAST-WEST LOW PRESSURE WILL REMAIN TO OUR  
SOUTH WHILE HIGH PRESSURE TO THE NORTH OVER NEW ENGLAND MAINTAINS  
THE NORTHEAST SURFACE FLOW. AS THE UPPER LOW MOVES EAST INTO VA,  
UPPER DIFLUENCE AHEAD OF IT AND A JET STREAK ROUNDING THE SE QUAD  
WILL RESULT IN STRONGER UVV OVERNIGHT. A BAND OF HEAVIER PRECIP IS  
FORECAST TO MOVE GENERALLY SOUTH TO NORTH ACROSS THE AREA FROM  
LATE EVENING THROUGH THE OVERNIGHT. ADDITION RAIN AMOUNTS ARE  
EXPECTED TO BE AROUND A HALF INCH OR SO, AND NO SIG FLOOD ISSUES  
ARE LIKELY.  
 
P-TYPE IS A CONCERN UP NORTH HOWEVER, WITH COLDER SURFACE AIR  
FILTERING INTO THE POCONOS AND FAR NW NJ OVERNIGHT. THIS IS EXPECTED  
TO RESULT IN SOME FREEZING RAIN LATE TONIGHT AND SUNDAY, WITH HIGHER  
ELEVATIONS ACCUMULATING PERHAPS A TENTH TO A QUARTER INCH OF ICE. A  
WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR THESE AREAS.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
 
 
ON SUNDAY, THE UPPER LOW WILL SLIDE BY JUST TO OUR SOUTH WHILE  
THE SURFACE LOW WILL RE-ORGANIZE JUST OFF THE NJ COAST. SOME  
AREAS OR BANDS OF PRECIP WILL LIKELY CONTINUE THROUGH MUCH OF  
THE DAY BUT AMOUNTS SHOULD BE LESS THAN OVERNIGHT. HIGH TEMPS ON  
SUNDAY WILL NOT BE ABLE TO RISE MUCH ABOVE TONIGHT'S LOWS. A  
WINTRY MIX MAY CONTINUE OVER HIGHER ELEVATIONS IN THE POCONOS,  
AND MAY BEGIN TO SPREAD FARTHER SOUTH TOWARDS EVENING AS  
TEMPERATURES BEGIN TO FALL.  
 
LOW PRESSURE SURFACE AND ALOFT WILL MOVE NORTHEAST AND AWAY FROM OUR  
AREA SUNDAY NIGHT. PRECIP SHOULD END FROM WEST TO EAST AND BE OVER  
BY DAWN MONDAY EXCEPT FOR SOME LINGERING SNOW FLURRIES IN THE  
POCONOS.  
 

 
   
LONG TERM /MONDAY THROUGH SATURDAY/
 
 
MONDAY THROUGH WEDNESDAY NIGHT...BY MONDAY MORNING, THE WEEKEND  
COASTAL STORM WILL BE CONTINUING TO PUSH OFFSHORE AND OUT TO  
SEA. MEANWHILE, HIGH PRESSURE WILL BEGIN BUILDING ACROSS THE  
OHIO VALLEY CREATING A MODEST PRESSURE GRADIENT WIND ACROSS THE  
REGION THROUGH TUESDAY. OTHERWISE, THE BUILDING HIGH PRESSURE  
WILL QUICKLY CLEAR THINGS OUT ACROSS MUCH OF OUR AREA. A FEW  
ISOLATED LIGHT SNOW SHOWERS OR FLURRIES WILL BE POSSIBLE ACROSS  
THE POCONOS ON MONDAY, HOWEVER GUIDANCE HAS SHOWN A FASTER  
DRYING TREND IN THIS ACTIVITY AS OF THE LAST FEW CYCLES. WINDS  
WILL INCREASE THROUGH THE DAY MONDAY AND PERSIST THROUGH THE  
OVERNIGHT HOURS AND INTO EARLY TUESDAY BEFORE RELAXING TUESDAY  
NIGHT AS THE HIGH SHIFTS JUST SOUTH OF OUR AREA. WINDS COULD  
POTENTIALLY GUST OVER 30 MPH ON MONDAY. EXPECTING TUESDAY TO BE  
AN EXCEPTIONALLY CLEAR, BUT CHILLY DAY WITH HIGHS ONLY TOPPING  
OUT IN THE UPPER 30S TO LOW 40S. CLEAR AND COLD WILL REMAIN THE  
STORY TUESDAY NIGHT WITH TEMPS BOTTOMING OUT IN THE LOW TO MID  
20S BY WEDNESDAY MORNING. FAIR WEATHER IS EXPECTED TO CONTINUE  
INTO WEDNESDAY WITH CLOUDS MOVING BACK INTO THE REGION BY LATER  
IN THE DAY. NOT AS COLD WEDNESDAY NIGHT WITH INCREASING CLOUD  
COVER AND LOWS AROUND NORMAL FOR THIS TIME OF YEAR.  
 
THURSDAY THROUGH SUNDAY...PLEASANT WEATHER THURSDAY WILL BEGIN TO GO  
DOWNHILL AS THE NEXT AREA OF LOW PRESSURE TRACKS TOWARD OUR REGION  
OUT THE GULF COAST STATES. UNFORTUNATELY, THIS WILL LIKELY LEAD TO  
SIMILAR CONDITIONS TO THIS CURRENT WEEKEND IN TERMS OF WIDESPREAD  
DREARINESS AND RAINFALL. LATEST GUIDANCE APPEARS TO BE IN GOOD  
AGREEMENT WITH A SURFACE LOW TRACKING UP THE APPALACHIANS INTO THE  
EASTERN GREAT LAKES REGION, STAYING OFF TO OUR WEST. THIS PLACES US  
IN THE WARM SECTOR WITH MOIST SOUTHERLY FLOW THURSDAY AND FRIDAY.  
HIGHS WILL TREND 5-10 DEGREES AVERAGE THESE DAYS, RANGING FROM NEAR  
40 IN THE POCONOS TO MID 50S ACROSS SOUTHERN DELAWARE. GIVEN THE  
FORECAST STRENGTH OF THE SYSTEM (CENTRAL PRESSURE DROPPING BELOW 980  
MB) AND STRONG WARM AIR ADVECTION, WOULDN'T BE SURPRISED TO SEE THESE  
FORECAST HIGHS NUDGE EVEN FURTHER UPWARDS. THE AMOUNT OF CLOUD COVER  
WILL ULTIMATELY PLAY A PART TOO. FORECAST SOUNDINGS FROM THE GFS  
SUGGEST SOME DRIZZLE AND/OR MIST MAY BE POSSIBLE AHEAD OF THE SYSTEM  
ON THURSDAY, SO THIS MAY HOLD THINGS IN CHECK A BIT.  
 
THE RAIN LOOKS TO MOVE THROUGH THE AREA IN TWO WAVES, AT LEAST  
GIVING US SOMEWHAT OF A BREAK IN BETWEEN. THE FIRST ROUND LOOKS TO  
MOVE THROUGH THURSDAY EVENING THROUGH THE DAY FRIDAY, WHILE THE  
SECOND WILL LIKELY BE MORE SHOWERY BEHIND THE COLD FRONT SATURDAY.  
SATURDAY WILL BE COOLER WITH HIGHS APPROACHING 50 ACROSS DELMARVA,  
WHILE STAYING IN THE MID 30S ACROSS THE NORTHERN PORTIONS OF THE  
AREA. THUS, SOME SNOW SHOWERS ARE POSSIBLE ACROSS THE POCONOS AND  
INTO THE HIGHER TERRAIN OF NORTHWEST NEW JERSEY SATURDAY. THE  
PRECIPITATION LIFTS OFF TO THE NORTH FOLLOWING THE SURFACE LOW  
SATURDAY NIGHT.  
 

 
   
AVIATION /21Z SATURDAY THROUGH THURSDAY/
 
 
IFR CONDITIONS REMAIN AT MOST OF OUR TAF SITES EXCEPT FOR ABE/RDG  
WHERE SOME DRIER AIR HAS FILTERED IN AT LOW LEVELS. RAIN IS EXPECTED  
TO RE-DEVELOP AND SPREAD NORTHWARD TONIGHT, BRINGING A RETURN TO IFR  
AT ALL SITES. NORTHEAST WINDS WILL CONTINUE THROUGH SUNDAY AND FOR  
PHL VCNTY AND EAST, THEY SHOULD INCREASE AND BECOME SOMEWHAT GUSTY  
OVERNIGHT INTO SUNDAY MORNING. IFR CONDITIONS ARE EXPECTED THROUGH  
MOST OF SUNDAY, WITH PERIODS OF LIGHT RAIN.  
 
OUTLOOK...  
 
MONDAY THROUGH MONDAY NIGHT...MOSTLY VFR CONDITIONS ARE EXPECTED.  
WEST TO NORTHWESTERLY WINDS THROUGH MAY GUST UP TO 25 KT THROUGH THE  
EVENING HOURS. A STEADY BREEZE IS EXPECTED TO LAST THROUGH THE  
OVERNIGHT HOURS.  
 
TUESDAY THROUGH TUESDAY NIGHT...VFR CONDITIONS EXPECTED. A STEADY  
BREEZE IS EXPECTED WITH NORTHWESTERLY WINDS GUSTING UP TO 20 KT  
DURING THE DAY.  
 
WEDNESDAY AND WEDNESDAY NIGHT...VFR CONDITIONS EXPECTED WITH LIGHT  
WEST TO SOUTHWESTERLY WINDS.  
 
THURSDAY THROUGH SUNDAY...MAINLY VFR CONDITIONS EXPECTED. MVFR TO  
IFR POSSIBLE WITH SNOW SHOWERS ACROSS THE NORTHERN PORTIONS OF THE  
AREA SATURDAY. SOUTHERLY WINDS THROUGH FRIDAY 10-15 KNOTS, TURNING  
WEST TO NORTHWESTERLY SATURDAY. GUSTS TO 25 KNOTS ARE POSSIBLE  
FRIDAY, ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF THE AREA.  
 

 
   
MARINE
 
 
SMALL CRAFT ADVISORIES FOR ALL FORECAST WATERS AND GALE WARNINGS FOR  
NORTHERN NJ COASTAL WATERS REMAIN IN PLACE. LOW PRESSURE ORGANIZING  
OFF THE NJ COMBINED WITH HIGH PRESSURE OVER NEW ENGLAND SHOULD  
PRODUCE A NORTHEAST GALE STARTING LATE TONIGHT AND CONTINUING  
THROUGH MUCH OF SUNDAY. SEAS WILL ALSO BUILD UP TO 7 TO 10 FEET  
DURING THIS TIME. VSBYS WILL BE LIMITED IN AREAS OF RAIN AND FOG  
THROUGH TONIGHT AND SUNDAY.  
 
OUTLOOK...  
 
MONDAY THROUGH MONDAY NIGHT...SCA CONDITIONS EXPECTED BY MONDAY  
AFTERNOON AS NORTHWESTERLY WINDS INCREASE THROUGH THE DAY WITH GALE  
FORCE GUSTS POSSIBLE MONDAY NIGHT. WAVES ARE EXPECTED TO BE IN  
THE 5-7 FEET RANGE MONDAY.  
 
TUESDAY THROUGH TUESDAY NIGHT...SCA CONDITIONS EXPECTED TO LAST  
THROUGH TUESDAY EVENING WITH GALE FORCE GUSTS POSSIBLE IN THE  
MORNING, OTHERWISE SUB-SCA CONDITIONS EXPECTED OVERNIGHT.  
 
WEDNESDAY THROUGH WEDNESDAY NIGHT...SUB-SCA EXPECTED.  
 
THURSDAY THROUGH SUNDAY...SUB-SCA CONDITIONS INITIALLY WILL LIKELY  
REACHING SCA CRITERIA FRIDAY, LASTING THROUGH SUNDAY MORNING. WINDS  
GUSTING FROM 25-30 KNOTS POSSIBLE DURING THIS TIMEFRAME. WAVES  
BUILDING FROM 8-13 FEET WILL BE POSSIBLE.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...WINTER WEATHER ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR  
PAZ054-055-062.  
NJ...WINTER WEATHER ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR  
NJZ001-007.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST SUNDAY FOR ANZ452>455.  
GALE WARNING UNTIL 6 PM EST SUNDAY FOR ANZ450-451.  
SMALL CRAFT ADVISORY UNTIL 9 AM EST SUNDAY FOR ANZ430-431.  
 

 
 

 
SYNOPSIS...DAVIS  
NEAR TERM...AMC  
SHORT TERM...AMC  
LONG TERM...DAVIS/STAARMANN  
AVIATION...AMC/DAVIS/STAARMANN  
MARINE...AMC/DAVIS/STAARMANN  
 
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