250  
FXUS61 KPHI 060224  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
924 PM EST THU MAR 5 2015  
   
SYNOPSIS
 
 
ARCTIC HIGH PRESSURE BUILDS IN OVERNIGHT AND FRIDAY. THE HIGH  
WILL THEN SETTLE TO OUR SOUTH ON SATURDAY. A WEAK LOW PRESSURE  
SYSTEM WILL TRACK TO OUR NORTH LATE SUNDAY INTO MONDAY, PULLING A  
COLD FRONT ACROSS OUR REGION ON MONDAY. HIGH PRESSURE SHOULD THEN  
BUILD INTO THE AREA TUESDAY INTO WEDNESDAY, WITH THE NEXT COLD  
FRONT SCHEDULED TO ARRIVE LATER WEDNESDAY INTO THURSDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
STORM OVER: PNS AND RER'S ARE POSTED. THE PNS FOR SNOW WILL  
FURTHER UPDATE OVERNIGHT.  
 
HAVE RAISED TEMPERATURES OVERNIGHT BECAUSE OF INCREASED WIND.  
RECORD LOWS STILL APPEAR TO HAVE A GOOD CHANCE OF OCCURRING AT  
KABE AND KRDG, PROVIDED LATE DECOUPLING OCCURS NEAR SUNRISE.  
 
THE 18Z NAM WAS MUCH BETTER AT AT ATTEMPTING TO DEPICT THE  
GUSTINESS ACROSS THE FORECAST AREA. THE 00Z NAM SUGGESTS WIND  
GUSTS WILL INCREASE 5 KT TOWARD 06Z BEFORE DECOUPLING ATTEMPTS TO  
BECOME MORE EXTENSIVE AROUND 09Z.  
 
AT 02Z, THE BACKEDGE OF THE THICK HIGH CLOUD DECK WAS MOVING EAST  
OF THE APPALACHIANS.  
 
LOW TEMPERATURES TONIGHT ARE BLENDED MET/MAV AND ADDITIONALLY FOR  
THE E PA AND NNJ COUNTRYSIDE ONLY, ADDED THE MODELED GFS TWO  
METER TEMPERATURES.  
 
WIND CHILLS ARE LIKELY TO FALL TO NEAR ZERO ACROSS MOST OF THE  
REGION, WITH THE POCONOS SEEING WIND CHILLS WHICH MAY GET CLOSE TO  
ADVISORY THRESHOLD FOR A FEW HOURS. GIVEN THE LIMITED WINDOW AND  
MARGINAL VALUES IN TERMS OF AND ADVISORY, WILL JUST CONTINUE  
MENTION IN THE HWO.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/
 
 
SUNNY DAY WITH HIGH PRESSURE BUILDING IN ON FRIDAY BUT STILL COLD.  
DID GO A TOUCH WARMER THAN MAV/MET GIVEN THE COOL DAYTIME BIAS  
WITH SNOW COVER. OTHER ELEMENTS STRAIGHT MAV/MET. CONTINUED  
NORTHWESTERLY WINDS UNDER 10 MPH OR SO.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
 
 
THE OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH  
FROM THE MIDWEST TO THE NORTHEAST AND MID ATLANTIC. AS SHORT WAVE  
ENERGY MOVES THROUGH THE FLOW, THIS FEATURE SHOULD AMPLIFY A LITTLE  
FOR A TIME OR TWO. THIS SHOULD EVENTUALLY WEAKEN AS ENERGY EJECTS  
ACROSS THE SOUTHERN PLAINS LATE IN THE WEEKEND AND EARLY NEXT WEEK,  
WITH A RIDGE POTENTIALLY BUILDING OFF THE SOUTHEASTERN U.S. COAST.  
THIS RESULTS IN THE UPPER-LEVEL FLOW TURNING MORE ZONAL NEXT WEEK.  
WE USED A MODEL BLEND FOR FRIDAY NIGHT THROUGH SUNDAY, THEN WENT  
WITH THE 12Z WPC GUIDANCE THEREAFTER. WE THEN MADE SOME ADJUSTMENTS  
AFTER ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES.  
 
FOR FRIDAY NIGHT AND SATURDAY...A SHORT WAVE TROUGH LOOKS TO SLIDE  
ACROSS THE AREA, HOWEVER A DRY AIRMASS RESULTS IN NO PRECIPITATION.  
AT THE SURFACE, HIGH PRESSURE BUILDS OVER THE AREA HOWEVER ITS  
CENTER SLIDES TO OUR SOUTH THROUGH SATURDAY. THIS WILL RESULT IN A  
GRADUAL RETURN FLOW BEING ESTABLISHED AND AFTER A VERY COLD START  
SATURDAY, SOME MODERATION IS EXPECTED IN THE AFTERNOON.  
 
FOR SUNDAY AND MONDAY...A SHORT WAVE IS FORECAST TO TRACK NEAR THE  
MIDWEST AND GREAT LAKES SUNDAY, THEN WELL TO OUR NORTH MONDAY. THIS  
WILL DRIVE WEAK LOW PRESSURE WELL TO OUR NORTH, HOWEVER A COLD FRONT  
IS FORECAST TO MOVE THROUGH DURING MONDAY. IT APPEARS THAT THE  
MOISTURE WILL BE LACKING WITH THIS FEATURE AS MUCH OF THE LIFT  
OCCURS WELL TO OUR NORTH. THERE COULD BE A SNOW SHOWER THOUGH SUNDAY  
NIGHT INTO MONDAY ACROSS THE FAR NORTHWEST. OTHERWISE, THE AIRMASS  
IS FORECAST TO CONTINUE TO MODIFY AS THE FLOW COMES MORE FROM THE  
WEST AND NOT THE NORTH.  
 
FOR TUESDAY AND WEDNESDAY...HIGH PRESSURE SHOULD SHIFT TO OUR EAST  
AS A COLD FRONT MOVES ACROSS THE MIDWEST AND THE GREAT LAKES. LOW  
PRESSURE APPEARS TO TRACK WELL TO OUR NORTH ONCE AGAIN, WITH A WARM  
FRONT LIFTING MOSTLY TO OUR NORTHWEST. WHILE THE FLOW LOOKS FAIRLY  
WEAK, ENOUGH WAA IS EXPECTED TO OCCUR TO ALLOW FOR FURTHER  
MODERATION OF THE AIRMASS WITH MANY AREAS GETTING INTO THE LOWER 50S  
WEDNESDAY AFTERNOON. THE COLD FRONT SHOULD BE ARRIVING LATE  
WEDNESDAY, HOWEVER GIVEN THE TRACK OF THE SURFACE LOW AND SHORT WAVE  
ALOFT IT ALSO LOOKS TO BE MOISTURE STARVED.  
 
FOR THURSDAY...A WEAK SURFACE HIGH IS ANTICIPATED TO MOVE ACROSS THE  
AREA, WHILE A FRONTAL BOUNDARY IS DRAPED FROM NEAR MAINE TO THE  
GREAT LAKES THEN INTO THE CENTRAL PLAINS. THE AIRMASS SHOULD BE MUCH  
MILDER WITH AFTERNOON HIGHS GETTING INTO THE 50S. THE OCEAN AND  
DELAWARE BAY ARE COLD AND IF THERE IS LIGHT ENOUGH FLOW, THEN A  
COOLING AFFECT CAN BE EXPECTED CLOSER TO THE COAST.  
 

 
   
AVIATION /02Z FRIDAY THROUGH TUESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
REMAINDER OF TONIGHT...VFR CIGS BECOME VFR CLEAR FM WEST TO EAST  
BETWEEN 3Z AND 6Z. NORTH-NORTHWEST WIND GUST AROUND 20 KT  
DIMINISHING TOWARD SUNRISE.  
 
FRIDAY...VFR CLEAR WITH SCT-BKN CIRRUS AOA 20000 FT LATE IN THE DAY.  
LIGHT WIND.  
 
OUTLOOK...  
FRIDAY NIGHT THROUGH SUNDAY...VFR OVERALL. A WEAK SYSTEM MOVING BY  
LATER SATURDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER ANY  
PRECIPITATION LOOKS TO STAY TO OUR NORTH AND WEST.  
 
MONDAY AND TUESDAY...VFR OVERALL. A WEAK COLD FRONT MOVING THROUGH  
MONDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER IT APPEARS THAT IT  
MOVES THROUGH DRY.  
 

 
   
MARINE
 
 
EXTENDING THE SCA ALONG LOWER DELAWARE BAY THROUGH MUCH OF THE  
NIGHT. WE MAY NEED TO ADD A SHORT FUSE SCA FOR UPPER DE BAY AROUND  
05Z? SCA CONTINUES ALONG THE ALTC COASTAL WATERS THROUGH THE  
OVERNIGHT HOURS.  
 
FOR FRIDAY, WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA.  
 
OUTLOOK...  
FRIDAY NIGHT AND SATURDAY...THE CONDITIONS ARE EXPECTED TO BE  
BELOW SMALL CRAFT ADVISORY CRITERIA, HOWEVER THE WINDS WILL  
INCREASE SOME FROM THE WEST-SOUTHWEST DURING SATURDAY. THERE IS A  
CHC FOR SOME LIGHT FREEZING SPRAY FRIDAY NIGHT AND SATURDAY  
MORNING.  
 
SUNDAY THROUGH TUESDAY...WE ARE ANTICIPATING SUB SMALL CRAFT  
ADVISORY CONDITIONS AS A WEAK FRONT MOVES THROUGH MAINLY DURING  
MONDAY.  
 

 
   
CLIMATE
 
 
WITH A SNOW COVER IN PLACE AND ANOTHER ARCTIC AIRMASS SETTLING  
INTO THE REGION AND RADIATIONAL COOLING OCCURRING WE HAVE ANOTHER  
CHANCE FOR MORE RECORD LOWS ACROSS THE REGION.  
 
FRIDAY 3/6  
 
RECORD LOWS  
 
ACY 10 1888  
PHL 10 1978  
ILG 11 1926  
ABE 7 1960  
TTN 7 1872  
GED 10 1978  
RDG 7 1978  
MPO -5 1909  
 
THE THE 9 PM FORECAST HAS KRDG AND KABE BREAKING THEIR RECORD LOW  
FRIDAY MORNING.  
 
SATURDAY 3/7  
 
RECORD LOWS  
 
ACY 10 1890  
PHL 9 1960  
ILG 11 1960  
ABE 1 1960  
TTN 7 1890  
GED 3 1960  
RDG 10 1989  
MPO -18 1911  
 
IT APPEARS THAT READING AND ATLANTIC CITY HAVE THE BETTER CHANCE  
OF GETTING TO THEIR RECORD LOW SATURDAY MORNING.  
 
RECORD DAILY SNOWFALL FOR THURSDAY MARCH 5  
 
RER'S POSTED FOR KILG AND KACY...BOTH 7.0 INCHES.  
 
PHL HAD 7.5 AND ALLENTOWN 6.7.  
 
KACY 0.3 - 1960  
KILG 3.7 - 1981  
KABE 7.0 - 1917  
KPHL 8.8 - 1981  
 
FWIW...WATER EQUIVALENCE OF TOTAL SNOW DEPTH IN PORTIONS OF EASTERN  
PA IS NOW WELL OVER 3 INCHES.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ450>455.  
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ431.  
 

 
 

 
SYNOPSIS...GORSE  
NEAR TERM...DRAG 923  
SHORT TERM...GAINES  
LONG TERM...GORSE  
AVIATION...DRAG/GORSE/O'HARA 923  
MARINE...DRAG/GORSE/O'HARA 923  
CLIMATE...  
 
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