864  
FXUS61 KPHI 202030  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
330 PM EST SUN JAN 20 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER CENTRAL CANADA BUILDS SOUTH INTO THE GREAT LAKES  
TONIGHT, THEN MOVES INTO THE MID-ATLANTIC ON TUESDAY BEFORE MOVING  
OFFSHORE TUESDAY NIGHT. LOW PRESSURE WILL AFFECT THE REGION  
WEDNESDAY THROUGH THURSDAY. A STRONG COLD FRONT PASSES THROUGH THE  
REGION THURSDAY NIGHT. HIGH PRESSURE RETURNS TO CLOSE OUT THE  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
LOW PRESSURE SYSTEM CONTINUING TO PULL AWAY AT THIS HOUR AS IT MOVES  
EAST OF LONG ISLAND. IN ITS WAKE TEMPERATURES ARE FALLING BEHIND A  
STRONG COLD FRONT WITH NW WINDS GUSTING 30-40+ MPH. A WIND ADVISORY  
REMAINS IN EFFECT FOR THE ENTIRE CWA UNTIL 5Z WITH WINDS GUSTING 35-  
45 MPH LATE THIS AFTERNOON THROUGH THIS EVENING. AS OF 2 PM, TEMPS  
STILL ABOVE FREEZING MOST OF THE I-95 CORRIDOR BUT FALLING SO EXPECT  
TEMPS TO DIP BELOW FREEZING HERE BY 4 PM WITH TEMPERATURES REACHING  
THE TEENS AND LOW 20S ACROSS THE AREA BY EARLY THIS EVENING EXCEPT  
SINGLE DIGITS IN SOUTHERN POCONOS. THIS WILL FREEZE ANY LINGERING  
STANDING WATER AND SLUSH PRODUCING VERY ICY CONDITIONS.  
 
FOR TONIGHT, THE BIG STORY WILL CONTINUE TO BE STRONG WINDS AND  
FALLING TEMPERATURES AS DEEPENING LOW PRESSURE MOVES NORTHEAST INTO  
THE CANADIAN MARITIMES. THE WINDS REMAIN STRONG AND GUSTY AT LEAST  
THROUGH THIS EVENING AND MAY NOT EVEN COME DOWN THAT MUCH OVERNIGHT  
AS THE STRONG GRADIENT PERSISTS OVER THE AREA. WINDS CONTINUING TO  
BLOW 15 TO 25 MPH THROUGH TONIGHT WILL COMBINE WITH BITTER COLD  
TEMPERATURES TO PRODUCE WIDESPREAD DANGEROUS, SUBZERO WIND CHILLS  
REACHING THE -10 (SOUTH) TO -25 (NORTH) RANGE BY LATER TONIGHT. FOR  
THIS REASON, WIND CHILL WARNINGS REMAIN IN EFFECT FOR CARBON AND  
MONROE COUNTIES WITH WIND CHILL ADVISORIES FOR THE REMAINDER OF THE  
CWA.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
 
 
FOR MONDAY, DEEP LOW PRESSURE CONTINUES TO DRIFT NORTHEAST THROUGH  
ATLANTIC CANADA WHILE HIGH PRESSURE NOSES SOUTHWARD INTO THE  
MIDWEST. THIS WILL KEEP THE TIGHT GRADIENT OVER THE AREA PRODUCING  
CONTINUING STRONG WINDS AND VERY COLD TEMPERATURES WITH BITTER WIND  
CHILLS DESPITE SKIES THAT WILL BE MAINLY SUNNY. EXPECT HIGH  
TEMPERATURES TO ONLY REACH THE SINGLE DIGITS ACROSS THE SOUTHERN  
POCONOS AND FAR NW NJ WITH TEENS FOR MOST OF THE REMAINDER OF THE  
AREA EXCEPT NEAR 20 OVER THE SOUTHERN DELMARVA. THIS WILL MEAN THAT  
EVEN DURING THE PEAK OF DAYTIME HEATING SUBZERO WIND CHILL VALUES  
WILL PERSIST FOR AREAS ALONG AND NORTH OF THE I-95 CORRIDOR.  
 
WINDS FINALLY EASE THROUGH MONDAY NIGHT INTO EARLY TUESDAY AS THE  
CENTER OF HIGH PRESSURE MOVES EASTWARD INTO THE AREA. FOLLOWING  
ANOTHER VERY COLD NIGHT MONDAY NIGHT (LOWS IN THE SINGLE DIGITS AND  
TEENS) TEMPERATURES WILL MODERATE TUESDAY BUT STILL BE BELOW  
AVERAGE. EXPECT HIGHS GENERALLY IN THE 20S TO LOW 30S BUT WITH  
LIGHTER WINDS AND MOSTLY SUNNY SKIES AS THE HIGH CRESTS OVER THE  
REGION. THIS HIGH MOVES OFFSHORE TUESDAY NIGHT WITH A DEVELOPING  
SOUTHERLY FLOW AND INCREASING CLOUDS AHEAD OF THE NEXT SYSTEM. AS A  
RESULT, TEMPERATURES TUESDAY NIGHT WON'T DROP TOO MUCH FROM  
TUESDAY'S HIGHS.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
A DEEP UPPER TROUGH WILL CONTINUE TO TRACK EAST THROUGH THE CENTRAL  
U.S. LOW PRESSURE DEVELOPS AT THE BASE OF THE TROUGH OVER THE GULF  
COAST STATES BY WEDNESDAY MORNING AS A PRIMARY LOW MOVES THROUGH THE  
GREAT LAKES. LOW PRESSURE LIFTS NORTH INTO THE REGION, AND LATEST  
FORECAST MODELS HAVE THIS SYSTEM PRIMARILY TAKING AN INLAND TRACK,  
WHICH WOULD ALLOW FOR A SURGE OF WARMER AIR ALONG THE EAST COAST.  
 
INITIALLY, THOUGH, TEMPERATURES WILL BE COLD ENOUGH FOR PRECIP TO  
START OUT AS SNOW ACROSS THE REGION WEDNESDAY MORNING, AND THEN THE  
RAIN/SNOW LINE WILL LIFT NORTH THROUGH THE DAY. SNOW ACCUMULATIONS  
SHOULD BE LIGHT, AND LOOK TO BE LIMITED TO AREAS NORTH AND WEST OF  
PHILLY, WITH POSSIBLY UP TO 2" IN THE SOUTHERN POCONOS.  
 
SURFACE LOW PRESSURE LIFTS NORTH THROUGH THE REGION WEDNESDAY NIGHT  
THROUGH THURSDAY MORNING, AND THEN UPPER TROUGH FOLLOWS THROUGH  
THURSDAY AFTERNOON. STRONG COLD FRONT AHEAD OF AN ARCTIC AIRMASS  
THEN PASSES THROUGH THURSDAY NIGHT.  
 
ABUNDANT LOW LEVEL MOISTURE WILL BE ASSOCIATED WITH THIS SYSTEM, AND  
LATEST FORECAST CALLS FOR 1.5-2" LIQUID QPF OVER A 24-36 HOUR  
PERIOD. SHOULD BE A LONG ENOUGH PERIOD TO KEEP WIDESPREAD FLOODING  
ISSUES LIMITED, BUT WILL HAVE TO MONITOR AS THE HEAVIEST RAIN WILL  
FALL WEDNESDAY NIGHT THROUGH THURSDAY MORNING.  
 
TEMPERATURES THEN FALL OFF GOING INTO THE WEEKEND, THOUGH THE  
COLDEST AIR WILL HOLD OFF UNTIL FRIDAY NIGHT. HIGHS ON FRIDAY WILL  
GENERALLY BE IN THE 30S, THEN FALL OFF INTO THE SINGLE DIGITS/TEENS  
FRIDAY NIGHT. HIGHS ON SATURDAY LOOK TO BE QUITE COLD, IN THE TEENS  
TO MID 20S.  
 
ANOTHER STORM MAY DEVELOP FOR SUNDAY.  
 

 
   
AVIATION /20Z SUNDAY THROUGH FRIDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
REST OF THIS AFTERNOON...VFR CEILINGS AROUND, WHICH THEN SCATTER  
OUT. NORTHWEST WINDS 18-24 KNOTS WITH GUSTS TO AROUND 35 KNOTS.  
 
TONIGHT AND MONDAY...VFR. NORTHWEST WINDS 18-22 KNOTS WITH GUSTS  
TO AROUND 35 KNOTS.  
 
OUTLOOK...  
MONDAY NIGHT AND TUESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH  
GUSTS TO AROUND 30 KNOTS DIMINISH MONDAY NIGHT, THEN BECOMING  
WEST TO SOUTHWEST LESS THAN 10 KNOTS TUESDAY.  
 
WEDNESDAY AND THURSDAY...SUB-VFR CONDITIONS ALONG WITH A PERIOD OF  
SNOW OR SNOW/RAIN MIX TO RAIN PROBABLE. SOUTHERLY WINDS AROUND 10  
KNOTS WEDNESDAY, BECOMING WEST-NORTHWEST AROUND 10 KNOTS THURSDAY.  
 
FRIDAY...SUB-VFR CONDITIONS AT TIMES POSSIBLE. WESTERLY WINDS 10-15  
KNOTS.  
 

 
   
MARINE
 
 
GALE WARNING EXTENDED THROUGH MONDAY EVENING. STRONG NORTHWESTERLY  
WINDS WILL CONTINUE THROUGH MONDAY AS ARCTIC AIR OVERSPREADS THE  
AREA RESULTING IN DEEPER MIXING. AS THIS OCCURS, FREEZING SPRAY WILL  
DEVELOP AND BECOME MORE WIDESPREAD BY LATER TONIGHT AND CONTINUE  
THROUGH MONDAY. A FREEZING SPRAY ADVISORY REMAINS IN EFFECT FOR  
MODERATE RATES OF ICE ACCRETION, AND THIS ADVISORY HAS BEEN EXTENDED  
THROUGH MONDAY EVENING TO MATCH UP WITH THE GALE WARNING. A LOW  
WATER ADVISORY MAY BE NEEDED ESPECIALLY MONDAY AFTERNOON GIVEN  
THE STRONG AND PERSISTENT OFFSHORE WINDS.  
 
OUTLOOK...  
TUESDAY...THE CONDITIONS (WINDS) ARE ANTICIPATED TO BE DROPPING  
BELOW SMALL CRAFT ADVISORY EARLY.  
 
WEDNESDAY AND THURSDAY...WINDS SHOULD INCREASE TO SMALL CRAFT  
ADVISORY CRITERIA WEDNESDAY, THEN DECREASE DURING THURSDAY WITH A  
WIND SHIFT FROM THE WEST. SEAS LOOK TO REMAIN AT 5 FEET OR HIGHER ON  
THE OCEAN WATERS.  
 
FRIDAY...SMALL CRAFT ADVISORY CONDITIONS PROBABLE.  
 

 
   
TIDES/COASTAL FLOODING
 
 
THE LAST OF THE MINOR TIDAL FLOODING WAS COMING TO AN END ON THE  
TIDAL DELAWARE RIVER AT MID AFTERNOON. ALSO, THERE WERE A FEW  
LINGERING POCKETS OF MINOR FLOODING ON THE UPPER PART OF BARNEGAT  
BAY WHICH SHOULD ALSO COME TO AN END SHORTLY.  
 
A STRONG NORTHWEST WIND IS EXPECTED FOR TONIGHT AND MONDAY AND IT  
WILL CONTINUE TO PUSH WATER AWAY FROM THE COAST. THEREFORE, NO  
ADDITIONAL TIDAL FLOODING IS ANTICIPATED BEYOND THAT WHICH OCCURRED  
TODAY.  
 
THE STRONG OFFSHORE WIND MAY RESULT IN SOME LOW WATER ISSUES, MAINLY  
ON PARTS OF THE LOWER DELAWARE RIVER AND THE UPPER DELAWARE BAY ON  
MONDAY. WE WILL CONTINUE TO MONITOR GUIDANCE TRENDS FOR THE EARLY  
MORNING AND ESPECIALLY FOR THE EVENING LOW TIDE ON MONDAY FOR A  
POSSIBLE LOW WATER STATEMENT OR ADVISORY. THE MOST SUSCEPTIBLE AREAS  
SEEMS TO BE NEW CASTLE COUNTY IN DELAWARE AND SALEM COUNTY IN NEW  
JERSEY.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ054-055-  
060>062-070-071-101>106.  
WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 1 PM EST MONDAY  
FOR PAZ060>062-070-071-101>106.  
WIND CHILL WARNING FROM 11 PM THIS EVENING TO 1 PM EST MONDAY  
FOR PAZ054-055.  
NJ...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NJZ001-007>010-  
012>027.  
WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 1 PM EST MONDAY  
FOR NJZ001-007>010-012>027.  
DE...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR DEZ001>004.  
WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 1 PM EST MONDAY  
FOR DEZ001>004.  
MD...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MDZ008-012-015-  
019-020.  
WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 1 PM EST MONDAY  
FOR MDZ008-012-015-019-020.  
MARINE...FREEZING SPRAY ADVISORY FROM 1 AM MONDAY TO MIDNIGHT EST  
MONDAY NIGHT FOR ANZ430-431-450>455.  
GALE WARNING UNTIL MIDNIGHT EST MONDAY NIGHT FOR ANZ430-431-  
450>455.  
 

 
 

 
SYNOPSIS...MPS  
NEAR TERM...FITZSIMMONS  
SHORT TERM...FITZSIMMONS  
LONG TERM...MPS  
AVIATION...GORSE  
MARINE...GORSE  
TIDES/COASTAL FLOODING...IOVINO  
 
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