019  
FXUS61 KPHI 090238  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
938 PM EST MON FEB 8 2016  
   
SYNOPSIS
 
 
A WEAK LOW PRESSURE SYSTEM WILL DEVELOP OFF OF THE MID ATLANTIC  
COAST OVERNIGHT. THIS SYSTEM WILL THEN GRADUALLY MOVE OUT TO SEA  
LATER TUESDAY INTO WEDNESDAY. A COLDER AIRMASS THEN SETTLES IN FOR  
THURSDAY AND FRIDAY. AN ARCTIC COLD FRONT FRIDAY NIGHT OR SATURDAY  
WILL USHER IN PERHAPS THE COLDEST AIR OF THE WINTER FOR NEXT WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
 
 
THE WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES REMAIN  
UNCHANGED ATTM.  
 
A RATHER CHAOTIC SETUP TONIGHT AS A DEEP UPPER-LEVEL TROUGH  
CONTINUES TO SETTLE INTO THE EASTERN U.S. AN UPPER AIR ANALYSIS  
SHOWED NUMEROUS SHORT WAVES REVOLVING AROUND THIS TROUGH, WITH A  
WEAK ONE NOW MOVING ACROSS OUR SOUTHERN AREAS. A MUCH STRONGER SHORT  
WAVE IS IN THE VICINITY OF KENTUCKY EARLY THIS EVENING AND THIS  
FEATURE IS MORE EVIDENT ON THE WATER VAPOR IMAGERY. AT THE SURFACE,  
WEAK LOW PRESSURE IS IN THE VICINITY OF THE EASTERN GREAT LAKES WITH  
EVEN A WEAKER ONE IN EASTERN NORTH CAROLINA. ON A SIDE NOTE, THE  
RADAR IMAGERY THIS EVENING SO FAR IS SHOWING WHAT APPEARS TO BE SOME  
ATLANTIC MOISTURE SEEDING IN THE LOWER LEVELS WITH THE NORTHEAST TO  
EAST FLOW IN THE OCEAN TO MONMOUTH COUNTY AREAS.  
 
THE SYNOPTIC/MESOSCALE EVOLUTION THROUGH THE NIGHT IS TRICKY AS WE  
START A SERIES OF INCOMING SHORT WAVES, WHICH WILL LEAD TO PERIODS  
OF ENHANCED LIFT. THIS WILL RESULT IN PERIODS OF SNOW, ESPECIALLY  
THE FARTHER SOUTH AND WEST ONE GOES. THE THERMAL PROFILES ARE SUCH  
THAT SOME RAIN OR A RAIN/SNOW MIX OCCURS FOR AWHILE ACROSS PORTIONS  
OF THE SOUTHERN AREAS AS JUST ENOUGH BOUNDARY WARMTH HANGS ON A  
LITTLE LONGER. SOME OF THESE AREAS THAT ALREADY STARTED WITH LIGHT  
RAIN HAS GONE OVER TO SNOW. THE FORECAST SOUNDINGS INDICATE THAT THE  
MID LEVEL LAPSE RATES BEGIN TO STEEPEN SOME OVERNIGHT AND THIS WILL  
CONTRIBUTE TO MORE COOLING. THE FAR SOUTHERN ZONES OF MARYLAND AND  
DELAWARE TO PERHAPS FAR SOUTHEASTERN NEW JERSEY MAY HAVE MIXING  
ISSUES FOR QUITE AWHILE. AS A RESULT, WE ADDED MORE RAIN AND A  
RAIN/SNOW MIX FOR SOME OF THESE PLACES FOR AWHILE. FARTHER TO THE  
NORTH, LOWER DEW POINTS ALONG WITH SOME COOLING ALOFT SHOULD RESULT  
IN ALL SNOW /AFTER A BRIEF START AS SOME RAIN OR MIX INTO  
PHILADELPHIA/.  
 
THE FORECAST CHALLENGE IS THE COVERAGE OF PRECIPITATION THROUGH THE  
NIGHT. THIS WILL BE MOSTLY FOCUSED ON SHORT WAVES TRAVERSING THE  
AREA AND BOOSTING THE VERTICAL MOTION AT TIMES. AS A RESULT, PERIODS  
OF SNOW/RAIN IS ANTICIPATED WITH LESSER PRECIPITATION ACROSS THE FAR  
NORTHERN AREAS. THE POPS WERE LOWERED ACROSS THE FAR NORTH FOR  
AWHILE /NOTING MUCH LOWER DEW POINTS THERE THIS EVENING SO FAR/. IT  
IS POSSIBLE THE ONGOING SURGE IN LIGHT PRECIPITATION BACKS OFF FOR  
AWHILE OVERNIGHT.  
 
A MORE PRONOUNCED SHORT WAVE TOWARD MORNING MAY ALLOW FOR A BURST OF  
SNOW FOR PARTS OF THE REGION, HOWEVER IT LOOKS LIKE ANY SNOW  
ACCUMULATIONS WILL BE ON THE LIGHTER SIDE THROUGH THE NIGHT. THE  
HOURLY TEMPERATURES AND DEW POINTS WERE ADJUSTED BASED ON THE LATEST  
OBSERVATIONS, THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN.  
 

 
   
SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/
 
 
A SURFACE TROUGH BECOMES BETTER DEFINED ACROSS OUR AREA AS LOW  
PRESSURE OFFSHORE SLOWLY LIFTS TO THE NORTHEAST. THE LIFT FROM THE  
SURFACE TROUGH, ALONG WITH A STRONGER SHORT WAVE EXPECTED DURING THE  
DAY, WILL CONTINUE TO COMBINE WITH ENHANCED MOISTURE IN THE  
DENDRITIC SNOW GROWTH ZONE AND IS EXPECTED TO LEAD TO A PERIOD OF  
ENHANCED SNOWFALL DURING THE DAY ACROSS PORTIONS OF OUR AREA. IT  
LOOKS TO NOT SNOW THE ENTIRE TIME, BUT WHEN IT DOES SNOW THERE COULD  
BE SOME HEAVIER BURSTS ESPECIALLY EARLY IN THE DAY AND THEN LATER IN  
THE DAY. ACROSS THE FAR SOUTHERN AREAS, A MIX OF RAIN AND SNOW WILL  
OCCUR AT TIMES WHICH WOULD LIMIT ACCUMULATIONS DURING THE DAYTIME.  
 
IT APPEARS THAT SOME OF THE HIGH RESOLUTION GUIDANCE ESPECIALLY  
CONTINUES TO KEY IN ON A STRONGER SHORT WAVE THAT ARRIVES LATER IN  
THE DAY. THIS FEATURE BOOSTS THE VERTICAL MOTION QUITE A BIT, WHICH  
IS ALSO TIED TO SOME AREAS OF 800-700 MB FRONTOGENESIS, AND IF THIS  
BECOMES REALITY THEN COMBINED WITH GOOD MOISTURE WITHIN THE SNOW  
GROWTH ZONE THE SNOWFALL RATES WILL INCREASE TOWARD EVENING. THIS  
MAY END UP BEING THE BEST CHC OF ACCUMULATING SNOW ACROSS MANY  
AREAS. DURING TIMES OF LIGHTER SNOW, ROADWAYS /TREATED ONES/ SHOULD  
BE IN GOOD SHAPE, HOWEVER WE WANT TO EMPHASIZE THAT HEAVIER  
SNOWFALL RATES WILL ALLOW FOR DETERIORATING ROAD CONDITIONS. IN  
ADDITION, THE PLACEMENT OF AN INVERTED TROUGH WILL BE KEY IN WHERE  
THE AXIS OF HEAVIER SNOW STARTS TO SET UP DURING THE COURSE OF THE  
DAY. THE MODEL GUIDANCE CONTINUES TO BATTLE THIS PLACEMENT OUT,  
HOWEVER OUR LATEST SNOWFALL GRAPHIC DEPICTS WHERE WE CURRENTLY  
THINK THE HEAVIEST AXIS WILL BE.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
 
 
A DEEP UPPER TROF/LOW WILL MOVE SLOWLY EASTWARD FROM THE MIDWEST  
ACROSS THE NORTHEAST AND MID ATLANTIC REGIONS OVER THE NEXT 2-3  
DAYS. THIS WILL RESULT IN PERIODS OF SNOW ACROSS THE FORECAST AREA  
FOR MUCH OF THIS TIME. THE SNOW EVENT WILL BE IN PROGRESS OVER THE  
AREA AT THE BEGINNING OF THIS EXTENDED PERIOD...TUES EVE...ALTHO  
IT LOOKS LIKE THE MAJORITY OF THE SNOW MAY HAVE ALREADY FALLEN BY  
THAT TIME. THIS UPPER SYS IS FAIRLY COMPLEX WITH A NUMBER OF  
SHRTWV/VORT CENTERS ROTATING AROUND IT SO IT IS SMWHT DIFFICULT TO  
SAY QUITE WHEN AND WHERE THE HEAVIER SNOW WILL FALL. OVERALL THIS  
DOES NOT LOOK TO BE A MAJOR STORM WITH NO STRONG SFC LOW  
DEVELOPMENT AND MAINLY JUST LIGHT OR MODERATE SNOW AT TIMES...AS  
NOTED ABOVE. FOR TOTAL SNOW...MOST GUIDANCE INCLUDING WPC SEEMED  
TO INDICATE A WEST-EAST BAND OF GREATER SNOWFALL ACROSS THE MIDDLE  
OF OUR FCST AREA AND THAT IS REFLECTED IN OUR TOTAL SNOW GRID.  
 
THE SNOW SHOULD HAVE MOSTLY ENDED BY EARLY WED MORNING...HOWEVER  
THE UPPER TROF WILL REMAIN OVER THE AREA DURING THE DAY ON WED SO  
SCATTERED SNOW SHOWERS WILL REMAIN A POSSIBILITY. THERE WILL BE  
DECENT COLD ADVECTION BEHIND THE SYSTEM FROM LATE WEDNESDAY INTO  
FRIDAY RESULTING IN TEMPS WELL BELOW NORMAL TOWARD THE END OF THE  
WEEK. HOWEVER EVEN COLDER ARCTIC AIR WILL PUSH INTO THE AREA ON  
SATURDAY WITH SOME OF THE COLDEST TEMPS OF THE WINTER EXPECTED AT  
THAT TIME. THIS PERIOD IS EXPECTED TO BE MOSTLY DRY HOWEVER THERE  
COULD BE SNOW SHOWERS OR SQUALLS WITH THE ARCTIC FRONTAL PASSAGE.  
 

 
   
AVIATION /03Z TUESDAY THROUGH SATURDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
OVERNIGHT...VFR CEILINGS LOWERING TO MVFR/IFR FROM SOUTH TO NORTH.  
SOME WILL CONTINUE TO MOVE NORTHEASTWARD, TAKING THE LONGEST TO  
REACH KABE AND KTTN. SOME LIGHT RAIN WILL START FROM KPHL ON SOUTH  
AND EAST, HOWEVER THIS IS EXPECTED TO QUICKLY MIX WITH AND CHANGE TO  
SNOW. THE SNOW WILL LOWER VISIBILITIES TO IFR WITH PERHAPS A BURST  
OF SNOW OCCURRING ESPECIALLY TOWARD DAYBREAK TUESDAY. EAST-SOUTHEAST  
WINDS MAINLY LESS THAN 10 KNOTS BECOMING NORTHEAST.  
 
TUESDAY...IFR CONDITIONS WITH PERIODS OF SNOW, HOWEVER ESPECIALLY  
NORTH OF KPHL THE CEILINGS MAY IMPROVE TO MVFR FOR AWHILE. WE  
ANTICIPATE A PERIOD OF MODERATE TO PERHAPS HEAVY SNOW TOWARD THE  
LATE AFTERNOON HOURS. THE AXIS OF THIS HEAVIER SNOW WILL DEPEND ON  
THE POSITIONING OF A BOUNDARY THAT WILL BISECT OUR REGION. OUR  
CONFIDENCE IN THE TIMING OF THE HEAVIER SNOW IS ON THE LOWER SIDE,  
HOWEVER IT DOES APPEAR MOSTLY EARLY IN THE DAY AND THEN ESPECIALLY  
LATER IN THE DAY. NORTHEAST WINDS MOSTLY 10-15 KNOTS, BECOMING NORTH  
LATER IN THE DAY.  
 
OUTLOOK...  
TUESDAY NIGHT...PERIODS OF SNOW EXPECTED TUE NIGHT BUT TAPERING  
OFF TO SNOW SHOWERS WED MORNING. EXPECT WIDESPREAD MVFR/IFR CONDS  
AND THE POSSIBILITY FOR LIFR IF THE HEAVIER SNOW BANDS DEVELOP.  
LIGHT WINDS.  
 
WEDNESDAY...LEFTOVER SNOW SHOWERS WILL TAPER OFF FROM WEST TO EAST  
DURING THE DAY, WITH CONDITIONS IMPROVING TO VFR. BREEZY WLY  
WINDS GUSTING TO 25 KT.  
 
THURSDAY AND FRIDAY...VFR AND BREEZY NW WINDS GUSTING 20 TO 30 KT.  
 
SATURDAY...POSSIBLE BRIEF MVFR OR IFR CONDS IN SNOW SHOWERS WINDS  
BECOMING NW AND GUSTING TO 30 KT OR GREATER.  
 

 
   
MARINE
 
 
SMALL CRAFT ADVISORY REMAINS IN EFFECT ACROSS THE ATLANTIC COASTAL  
WATERS THROUGH TODAY AND TUESDAY. WINDS HAVE DIMINISHED AS THE FIRST  
STRONG LOW PRESSURE SYSTEM PULLS AWAY, BUT WAVES WILL REMAIN  
ELEVATED. ALSO, WINDS MAY INCREASE AGAIN TUESDAY AS ANOTHER LOW LOW  
STRENGTHENS OFF THE COAST.  
 
OUTLOOK...  
TUESDAY NIGHT THRU THURSDAY...SMALL CRAFT CONDITIONS EXPECTED TO  
CONTINUE THROUGH THE PERIOD WITH GALES POSSIBLE ON THURSDAY.  
 
FRIDAY...SUB SCA CONDITIONS EXPECTED.  
 
SATURDAY...WINDS/SEAS INCREASING AGAIN TO SCA AND POSSIBLY GALE  
CONDITIONS.  
 

 
   
TIDES/COASTAL FLOODING
 
 
WIDESPREAD MINOR COASTAL FLOODING OCCURRED ALONG THE COASTS OF NEW  
JERSEY AND DELAWARE THIS EVENING. THE MINOR FLOODING WILL LINGER  
OVERNIGHT AND IT WILL WORK ITS WAY UP DELAWARE BAY AND INTO THE  
TIDAL DELAWARE RIVER.  
 
TUESDAY MORNING'S HIGH TIDE...WITH A STRONGER NORTHEAST FLOW AND  
HIGHER WAVE ACTION, WIDESPREAD MODERATE COASTAL FLOODING WITH  
POCKETS OF MAJOR COASTAL FLOODING IS EXPECTED ALONG THE DE AND NJ  
OCEANFRONT DURING THE TIME OF HIGH TIDE. FOR DELAWARE BAY, THERE IS  
A HIGHER LIKELIHOOD OF MODERATE FLOODING NEAR THE TIME OF HIGH TIDE.  
THE COASTAL FLOOD WARNING CONTINUES FOR THE ENTIRE DE AND NJ  
OCEANFRONT AND DELAWARE BAY THROUGH THE TUESDAY MORNING HIGH TIDE.  
WE EXPECT MINOR FLOODING FOR TIDAL SECTIONS OF THE DELAWARE RIVER  
AND ITS TIDAL TRIBUTARIES WHEN HIGH TIDE OCCURS ON TUESDAY  
AFTERNOON. A COASTAL FLOOD ADVISORY CONTINUES THERE.  
 
OVERALL, FOR THE DE AND NJ OCEANFRONT, INCLUDING DELAWARE BAY, WE  
EXPECT THE GREATEST IMPACT WITH THE HIGH TIDE TUESDAY MORNING  
COMPARED WITH THE PREVIOUS TWO HIGH TIDES. IN FACT, THERE WILL BE  
MORE WIDESPREAD ROAD FLOODING WITH ROAD CLOSURES IN SOME AREAS.  
THERE WILL ALSO BE THE POSSIBILITY OF DAMAGE TO MORE VULNERABLE  
STRUCTURES, ESPECIALLY FACTORING IN BREAKING WAVES OF 4 TO 8 FEET,  
WHICH COULD ALSO RESULT IN SIGNIFICANT BEACH EROSION. IN PARTICULAR,  
SOME BEACH AREAS WILL BE MORE SUSCEPTIBLE TO DAMAGE DUE TO BEACH  
EROSION AND DAMAGE TO SHORE STRUCTURES THAT OCCURRED IN LATE  
JANUARY, WITH EMPHASIS ON CAPE MAY COUNTY NJ AND THE DE  
OCEANFRONT.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ060-  
061-103-105.  
WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR PAZ070-071-  
101-102-104-106.  
COASTAL FLOOD ADVISORY UNTIL 5 PM EST TUESDAY FOR PAZ070-071-  
106.  
NJ...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR NJZ009-  
010-012>015.  
COASTAL FLOOD WARNING UNTIL 1 PM EST TUESDAY FOR NJZ012>014-  
020>027.  
WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR NJZ016>025-  
027.  
COASTAL FLOOD WARNING UNTIL 3 PM EST TUESDAY FOR NJZ016.  
COASTAL FLOOD ADVISORY UNTIL 5 PM EST TUESDAY FOR NJZ015-  
017>019.  
DE...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR DEZ003-  
004.  
COASTAL FLOOD WARNING UNTIL 1 PM EST TUESDAY FOR DEZ002>004.  
WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR DEZ001-002.  
COASTAL FLOOD WARNING UNTIL 3 PM EST TUESDAY FOR DEZ001.  
MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR MDZ019-  
020.  
WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR MDZ008-012-  
015.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ450>455.  
 

 
 

 
SYNOPSIS...AMC/GORSE  
NEAR TERM...GORSE  
SHORT TERM...GORSE/ROBERTSON  
LONG TERM...AMC  
AVIATION...AMC/GORSE  
MARINE...AMC/ROBERTSON  
TIDES/COASTAL FLOODING...FRANCK/IOVINO  
 
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