567  
FXUS61 KPHI 200908  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
408 AM EST THU FEB 20 2020  
   
SYNOPSIS
 
 
HIGH PRESSURE LOCATED OVER THE UPPER MIDWEST WILL CONTINUE TO  
SLOWLY SHIFT SOUTH AND EAST OVER THE NEXT FEW DAYS, WITH THE CENTER  
OF THE HIGH FINALLY PASSING OFF THE CAROLINA COAST ON SUNDAY.  
LOW PRESSURE IS EXPECTED TO PROGRESS FROM THE MIDDLE MISSISSIPPI  
RIVER VALLEY ON MONDAY TO THE NORTHEASTERN STATES ON TUESDAY.  
ANOTHER AREA OF LOW PRESSURE MAY TRAIL BEHIND THIS LOW AND  
IMPACT THE AREA TOWARDS THE MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM / THROUGH MIDNIGHT/
 
 
 
THE MAIN INFLUENCE ON OUR WEATHER THE NEXT FEW DAYS WILL BE THE  
AREA OF STRONG HIGH PRESSURE CURRENTLY CENTERED OVER THE UPPER  
MIDWEST. COOL NORTHERLY FLOW WILL PREVAIL ON THE EASTERN  
PERIPHERY OF THIS FEATURE TODAY, AND HIGHS ARE EXPECTED TO BE  
AROUND 5-10 DEGREES BELOW NORMAL (E.G. MOSTLY UPPER 30S TO LOWER  
40S). THE UPPER-LVL JET AXIS WILL PIVOT OVERHEAD TODAY WHICH  
SHOULD SUPPORT A STEADY STREAM OF MID-HIGH CLOUDS.  
 
ALTHOUGH THE VAST MAJORITY OF THE AREA SHOULD REMAIN DRY DUE TO  
THE INFLUENCE OF THE AFOREMENTIONED HIGH THERE ARE TWO POTENTIAL  
AREAS THAT MAY SEE PRECIPITATION LATER THIS AFTERNOON INTO THIS  
EVENING. THE FIRST (AND MORE LIKELY) OF THESE AREAS IS SOUTHERN  
DELMARVA AND FAR SOUTHERN NJ, WHERE THE NORTHERN FRINGE OF THE  
MOISTURE ENVELOPE ASSOCIATED WITH A STRENGTHENING LOW OFF THE NC  
COAST WILL ENCROACH UPON OUR "DRY BUBBLE". GENERALLY THINK THE  
HIGH WILL WIN OUT AND KEEP ANY SIGNIFICANT PRECIPITATION SHUNTED  
TO OUR SOUTH. THAT BEING SAID DUE TO THE COOL AND DRY AIRMASS  
IF PRECIPITATION IS ABLE TO FALL IT WOULD LIKELY COME IN THE  
FORM OF SNOW, AND CAN'T RULE OUT A DUSTING TO A FEW TENTHS OVER  
THE FAR SOUTH THIS AFTERNOON INTO THIS EVENING IF THINGS  
OVER-PERFORM RELATIVE TO CURRENT EXPECTATIONS.  
 
THE SECOND POTENTIAL AREA OF PRECIPITATION (IN THE FORM OF  
FLURRIES OR LIGHT SNOW SHOWERS) WOULD BE IN FAR NORTHERN AND  
WESTERN PORTIONS OF OUR AREA IN ASSOCIATION WITH A COLD FRONT  
AND APPROACHING SHORTWAVE LATE THIS AFTERNOON. SINCE IT WILL BE  
EVEN DRIER RELATIVE TO DELMARVA GENERALLY DON'T HAVE HIGH  
EXPECTATIONS THAT MEASURABLE SNOWFALL WILL OCCUR WITH THIS  
FRONT, AND CONSEQUENTLY LEFT MOST AREAS WITH NON-MENTIONABLE  
POPS OUTSIDE OF THE POCONOS AND WESTERN BERKS COUNTY.  
 

 
   
SHORT TERM /TONIGHT/
 
 
THE COLD FRONT WILL CONTINUE TO PUSH THROUGH THE REGION FOR THE  
FIRST HALF OF THE OVERNIGHT PERIOD, WHILE THE APPROACHING  
SHORTWAVE SHOULD BEGIN TO LIFT THE LOW TO OUR SOUTH OUT TO SEA.  
DRIER AIR FILTERING IN BEHIND THE FRONT SHOULD RESULT IN  
CLEARING SKIES FROM N-S WITH MOSTLY CLEAR SKIES EXPECTED BY  
FRIDAY MORNING. ANY LIGHT PRECIPITATION EITHER ASSOCIATED WITH  
THE FRONT OR THE SOUTHERN LOW SHOULD CLEAR THE AREA BY MIDNIGHT.  
 
OVERNIGHT LOWS WILL BE A BIT CHALLENGING AS THIS WILL BE A  
SITUATION WHERE THE WINDS WILL REMAIN SOMEWHAT ELEVATED BEHIND  
THE FRONT, BUT AT THE SAME TIME THERE WILL BE FAIRLY STRONG COLD  
ADVECTION. CONSEQUENTLY WENT TOWARDS THE MEAN OF GUIDANCE WHICH  
RESULTS IN A FAIRLY COOL NIGHT WITH LOWS BOTTOMING OUT IN THE  
UPPER TEENS TO LOWER 20S BY FRIDAY MORNING, BUT TEMPERATURES  
COULD BE LOCALLY COLDER IN PRONE SPOTS (E.G. PINE BARRENS, PA  
VALLEYS) IF WE DECOUPLE.  
 

 
   
LONG TERM /FRIDAY THROUGH WEDNESDAY/
 
 
FRIDAY THROUGH SUNDAY...THE START OF THE EXTENDED WILL BE QUITE  
UNEVENTFUL AS THE EXPANSIVE CENTRAL US HIGH VERY SLOWLY DRIFTS  
SOUTHEASTWARDS AND ALSO WEAKENS. AT UPPER LEVELS THE AREA WILL  
REMAIN DISPLACED FROM BOTH THE SOUTHERN AND NORTHERN STREAMS  
WHICH WILL FURTHER SUPPORT THE TRANQUIL WEATHER... AND EVEN  
CLOUDS WILL BE HARD TO COME BY.  
 
FRIDAY WILL REMAIN ON THE COOL SIDE WITH HIGHS GENERALLY ONLY IN  
THE MID TO UPPER 30S BUT WE WILL BEGIN TO WARM UP QUICKLY OVER  
THE WEEKEND AS THE LOW-LVL FLOW BACKS TO MORE WESTERLY AND THEN  
SOUTHWESTERLY. SATURDAY'S HIGHS SHOULD BE IN THE UPPER 40S TO  
LOWER 50S, WHILE SUNDAY'S HIGHS WILL GENERALLY BE IN THE LOW TO  
MID 50S. THESE TEMPERATURES COMBINED WITH ABUNDANT SUNSHINE  
SHOULD MAKE FOR A VERY NICE WEEKEND.  
 
MONDAY THROUGH WEDNESDAY... THE HIGH WILL HAVE FINALLY SHIFTED  
OFFSHORE BY MONDAY AND SOME MOISTURE WILL START TO RETURN AS  
SOUTHERLY FLOW INCREASES. GUIDANCE HAS SLOWED A BIT WITH THE  
ARRIVAL OF THE NEXT STORM SYSTEM (WITH SOME LINGERING DISCREPANCIES  
AMONG INDIVIDUAL MODELS), DELAYING IT UNTIL MONDAY NIGHT OR  
TUESDAY. THE THERMAL PROFILES DO NOT SUPPORT MUCH CHANCE OF  
SIGNIFICANT WINTRY PRECIPITATION WITH THIS SYSTEM SO AT THE  
MOMENT THINK THIS WILL BE PRIMARILY A RAIN EVENT (WITH THE MOST  
LIKELY TIME FOR STEADY RAIN BEING TUESDAY). THERE IS THE  
POTENTIAL FOR A SECONDARY SYSTEM WEDNESDAY INTO THURSDAY OF NEXT  
WEEK BUT DETAILS ARE LACKING AT THIS TIME.  
 
TEMPERATURES WILL LIKELY BE QUITE WARM ON MONDAY AND TUESDAY  
WITH HIGHS GENERALLY IN THE 50S (WITH SOME POTENTIAL FOR 60S  
EVEN), BEFORE COOLING OFF A BIT ON WEDNESDAY BEHIND THE COLD  
FRONT. OF NOTE THERE IS A PRETTY STRONG SIGNAL IN THE ENSEMBLE  
GUIDANCE FOR A PERIOD OF COLDER TEMPERATURES LATE NEXT WEEK BUT  
SPECIFIC DETAILS ARE NATURALLY LACKING.  
 

 
   
AVIATION /08Z THURSDAY THROUGH MONDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
TODAY...VFR CONDITIONS EXPECTED WITH MID AND HIGH CLOUDS  
EARLY, WITH SOME LOWER CEILINGS (BUT STILL VFR) MOVING IN LATE  
THIS AFTERNOON. WINDS WILL GENERALLY BE NW-N AROUND 5 KTS. HIGH  
CONFIDENCE.  
 
TONIGHT... VFR WITH CEILINGS CLEARING OUT THROUGH THE FIRST HALF  
OF THE NIGHT. N/NE WINDS AROUND 10-15 KTS EXPECTED.  
 
OUTLOOK...  
 
FRIDAY-SUNDAY...VFR WITH NORTH-NORTHWEST WINDS 5 TO 10 KNOTS  
FRIDAY BECOMING WESTERLY 10 KTS ON SATURDAY, AND THEN  
SOUTHWESTERLY 5-10 KTS ON SUNDAY. WINDS MAY BECOME LIGHT AND  
VARIABLE OVERNIGHT EACH DAY. HIGH CONFIDENCE.  
 
MONDAY...MAINLY VFR. A CHANCE OF RAIN IN THE AFTERNOON. SOUTH  
WIND 5 TO 10 KNOTS. HIGH CONFIDENCE.  
 

 
   
MARINE
 
 
SEAS WILL GENERALLY BE 2 FT OR LESS THROUGH MOST OF THE DAY  
TODAY WITH NORTHERLY WINDS 5-10 KTS AND GUSTS 10-15KTS.  
 
BEHIND A COLD FRONT THIS EVENING NORTHERLY WINDS SHOULD INCREASE  
TO SUSTAINED 20-25 KTS WITH GUSTS UP TO 30KTS WHILE SEAS WILL  
INCREASE TO 4-6 FT BY FRIDAY MORNING. SOME SNOW SHOWERS WILL BE  
POSSIBLE LATE THIS AFTERNOON INTO THIS EVENING ACROSS THE FAR  
SOUTHERN WATERS.  
 
OUTLOOK...  
 
FRIDAY...SCA CONDITIONS ARE EXPECTED THROUGH THE EARLY  
AFTERNOON FRIDAY AFTER WHICH TIME WINDS AND SEAS SHOULD DIP  
BELOW SCA CRITERIA.  
 
FRIDAY NIGHT THROUGH MONDAY...SUB-SCA CONDITIONS EXPECTED  
THROUGH THE PERIOD WITH SEAS GENERALLY RUNNING 2-3 FT AND GUSTS  
20 KTS OR LESS.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST FRIDAY  
FOR ANZ452>455.  
SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST FRIDAY  
FOR ANZ430-431-450-451.  
 

 
 

 
SYNOPSIS...CARR  
NEAR TERM...CARR  
SHORT TERM...CARR  
LONG TERM...CARR  
AVIATION...CARR  
MARINE...CARR  
 
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