Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 271150 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 650 AM EST FRI FEB 27 2015 .SYNOPSIS... WEAK IMPULSE MOVES THROUGH THE AREA TODAY FOLLOWED BY AN EXTENSIVE HIGH PRESSURE SYSTEM FOR A MAJORITY OF THE WEEKEND. AS THE HIGH SLIPS OFF THE COAST ON SUNDAY A WEAK WARM FRONT LIFTS THROUGH THE REGION AS LOW PRESSURE PASSES TO OUR WEST AND ITS ASSOCIATED COLD FRONT PUSHES THROUGH ON MONDAY. ANOTHER LOW PRESSURE EJECTS OUT OF THE CENTRAL PLAINS AND CROSSES OUR REGION ON TUESDAY INTO WEDNESDAY. THE LOWS ASSOCIATED COLD FRONT PUSHES THROUGH LATER ON WEDNESDAY WITH ANOTHER EXPANSIVE HIGH PRESSURE SYSTEM FILLING IN BEHIND IT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CURRENT SNOW SHOWERS ACROSS CENTRAL PA ARE STRUGGLING TO CROSS THE MOUNTAINS TO MAKE IT INTO OUR CWA. IN ADDITION, A VERY DRY BOUNDARY LAYER AS INDICATED BY LARGE DEW POINT DEPRESSIONS, MEANS THAT EVEN WITH THE FEW LIGHT RADAR ECHOS IN OUR CWA, VERY LITTLE IS REACHING THE GROUND. NOT EXPECTING MUCH ADDITIONAL LOW LEVEL MOISTURE ADVECTION THROUGH THE DAY TODAY, SO WHEN THE UPPER LEVEL SHORT WAVE TROUGH DOES APPROACH OUR REGION BY MID DAY, SIMILAR LIMITATIONS WILL BE IN PLACE FOR ANY PRECIP. THEREFORE, DECREASED POPS SLIGHTLY ESPECIALLY ALONG THE DELAWARE VALLEY. AS FOR TEMPERATURES, AGREE WITH THE PREVIOUS SHIFT THAT RECENT GUIDANCE HAS OVERESTIMATED THE IMPACT OF THE SNOW PACK ON THE DAY TIME TEMPERATURES, SO WENT SLIGHTLY ABOVE GUIDANCE WITH HIGH RANGING FROM THE UPPER TEENS IN THE POCONOS TO AROUND FREEZING IN SOUTHERN DELAWARE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... AT LEAST ONE MODEL IS DEPICTING LOW LEVEL CLOUDS DEVELOPING BY THIS EVENING. HOWEVER, THIS SEEMS UNLIKELY WITH THE SYNOPTIC PATTERN OF A SURFACE HIGH SLIDING EAST TOWARD THE REGION AS FLOW ALOFT TRANSITIONS TO MORE ZONAL FLOW. THEREFORE, EXPECT CLEARING SKIES THIS EVENING INTO THE OVERNIGHT HOURS. THIS, COMBINED WITH SUBSIDENCE IN THE LOW LEVELS AND LIGHT WINDS WILL LEAD TO PRIME RADIATIONAL COOLING CONDITIONS, ESPECIALLY FOR LOCATIONS THAT STILL HAVE A SNOW PACK. THUS, WENT SLIGHTLY BELOW GUIDANCE FOR LOWS. && .LONG TERM /SATURDAY THROUGH THURSDAY/... MEDIUM RANGE GUIDANCE IS IN PRETTY DECENT AGREEMENT WITH THE LARGE SCALE FEATURES THROUGH THE EXTENDED PERIOD. THE MID-LEVELS TAKE ON MORE OF A ZONAL-ISH FLOW OVER THE WEEKEND WITH THE NEXT EMBEDDED WAVE EXPECTED BY MONDAY FOLLOWED BY DEEPENING RIDGING THROUGH MID- WEEK AS THE LONGWAVE TROUGH RELOADS TO OUR WEST AND ADVANCES THROUGH LATE IN THE PERIOD. SATURDAY...HIGH PRESSURE WILL BE OVERHEAD ALLOWING FOR LOTS OF SUBSIDENCE AND MOSTLY CLEAR SKIES. TEMPERATURES WILL BE RATHER COLD STILL, NEARLY 20 DEGREES UNDER CLIMO FOR THE LAST DAY OF METEOROLOGICAL WINTER. SUNDAY - MONDAY...ZONAL-ISH FLOW TURNS A BIT SHARPER AS THE BROAD TROUGH RELOADS WELL TO OUR WEST. ANOTHER PASSING SHORTWAVE ALOFT APPROACHES AND PUSHES A COLD FRONT THROUGH THE REGION VERY LATE SUNDAY INTO MONDAY MORNING. OUT AHEAD OF THE FRONT TEMPERATURES ARE ABLE TO MODIFY A BIT THANKS TO THE DEPARTING HIGH PRESSURE NOW OFF THE COAST AND A LIGHT RETURN FLOW SETTING UP. WE CONFINED THE HIGHER POPS UNTIL LATE SUNDAY NIGHT JUST AHEAD AND WITH THE FRONTAL PASSAGE. DECENT AMOUNT OF THETA-E ADVECTION OCCURRING AHEAD OF THE COLD FRONT WITH ENOUGH LIFT FOR A LIGHT SNOW TO START BEFORE A WINTRY MIX OF RAIN/SNOW/SLEET/FREEZING RAIN OCCURS, MOSTLY ACROSS THE SOUTHERN HALF OF THE CWA, BY MONDAY MORNING. THERE COULD BE SOME WAK COLD AIR DAMMING OCCURRING, EVEN AS WINDS TURN MORE EASTERLY, BUT GIVEN THE ARCTIC HIGH WILL BE OFFSHORE AND NOT EXPECTING A HUGE REPSONSE IN THE LOW-LEVEL WINDS THE GROUND COULD STILL BE COLD ENOUGH FOR SOME LIGHT FREEZING RAIN...MORESO THEN WE ARE CURRENTLY CARRYING IN THE FORECAST. THE BEST CHANCES FOR AN ALL SNOW EVENT REMAINS AROSS OUR NORTHERN MOST ZONES WHERE THE WARM NOSE GETS CLOSE BUT DOES NOT HAVE ENOUGH PUSH TO MOVE THROUGH, PRIOR TO THE COLD FRONT USHERING IN ANOTHER SHOT OF COLDER AIR. WE ARE CURRENTLY CARRYING A FEW INCHES OF SNOW ACROSS THE POCONOS AT THIS TIME. TUESDAY - THURSDAY...WITH THE COLD FRONT TO OUR EAST AND A BRIEF SHOT OF HIGH PRESSURE BEHIND IT, THE NEXT SYSTEM, FORMING DEEP IN THE SOUTH, BEGINS TO ENTER THE REGION FROM THE SOUTHWEST LATER ON TUESDAY. A LIGHT ONSHORE FLOW WILL HELP TO ENHANCE THE LOW-LEVEL MOISTURE FLUX WHEN COMBINED WITH A STRONG LOW-LEVEL SOUTHERLY SURGE OF WARM/MOIST AIR. THIS EVENT COULD HAVE A COPIOUS AMOUNT OF MOISTURE WITH IT, GIVEN ITS ORIGIN AND THE MODIFYING AIRMASS WE`LL HAVE IN PLACE. TOO EARLY FOR PTYPE SPECIFICS BUT IT DOES APPEAR TO BE ANOTHER MIXED EVENT. THIS SYSTEMS COLD FRONT DRAGS THROUGH RATHER SLOWLY, AS THE TROUGHING TO OUR WEST SHARPENS AND SLOWS IT DOWN A BIT. THIS COULD ALLOW FOR A LONGER DURATION EVENT SO WE CARRY CHANCE POPS THROUGH THE FIRST HALF OF THURSDAY BEFORE DRYING OUT. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. GENERALLY VFR CONDITIONS THROUGH THE TAF PERIOD. BRIEF IFR AND MVFR CONDITIONS WITH SHSN ARE POSSIBLE AT KPHL, KILG, AND KPNE THROUGH 14Z. ANOTHER CAVEAT IS THAT THE GFS IS INDICATING MVFR CEILINGS DEVELOPING THIS EVENING FOR PRIMARILY THE DELAWARE VALLEY. THIS SEEMS UNLIKELY AS IT HAS BEEN OVERESTIMATING THE MOISTURE IN THE LOW LEVELS THE LAST FEW DAYS, SO HAVE CHOSEN TO DISCOUNT THIS FOR NOW. OTHERWISE, SHOULD SEE SKIES SLOWLY CLEARING THROUGH THE DAY AND LIGHT NORTHWESTERLY WINDS. OUTLOOK... SATURDAY - SUNDAY MORNING...VFR. NORTHERLY WINDS PREVAIL AS HIGH PRESSURE NOSES IN FROM THE WEST. SUNDAY NIGHT - MONDAY...MVFR/IFR EXPECTED WITH SNOW TO RAIN/FREEZING RAIN POSSIBLE BY EARLY MONDAY MORNING. TUESDAY...VFR. && .MARINE... WINDS HAVE ALREADY SUBSIDED AND SHOULD REMAIN BELOW SCA CRITERIA TODAY AND TONIGHT, ALTHOUGH A FEW GUSTS NEAR 20 KT ARE POSSIBLE OVER THE OCEAN WATERS THIS EVENING. SEAS ON THE OCEAN WILL SLOWLY SUBSIDE BELOW SCA CRITERIA THROUGH THIS AFTERNOON. ONCE THEY DO, WAVE HEIGHTS SHOULD REMAIN BELOW 5 FT OVERNIGHT TONIGHT. OUTLOOK... SATURDAY - SUNDAY...SUB-SCA EXPECTED, THOUGH PERSISTENT NORTHEAST WINDS MAY ALLOW FOR BUILDING SEAS ACROSS OUR SOUTHERN ZONES. SUNDAY NIGHT - MONDAY...POSSIBLE SCA CONDITIONS LATE ON SUNDAY AHEAD OF AN APPROACHING COLD FRONT WITH INCREASING SOUTHERLY WINDS AND BUILDING SEAS EXPECTED. BETTER CHANCE BEHIND COLD FRONT PASSAGE ON MONDAY WITH GUSTY WEST WINDS. TUESDAY...SUB-SCA EXPECTED. && .CLIMATE... RECORDS FOR FRIDAY AND SATURDAY. NOTE RECORDS FOR FRIDAY UNLIKELY BUT POSTED JUST IN CASE ONE OR 2 ARE APPROACHED AT 1159 PM FRIDAY EVENING. THERE IS A GREATER CHANCE OF RECORDS SATURDAY. POR / SITE / FEB 27 FEB 28 1872 / KPHL / 6 1900 9 1934 1874 / KACY / 7 1934* 2 1934 1894 / KILG / 5 1934 -5 1934 1922 / KABE / -2 1963 -10 1934 1869 / KRDG / 4 1934* 3 1934 1865 / KTTN / 6 1934 1 1934 1948 / KGED / 10 1963 8 1950 1901 / KMPO / -9 1993 -15 1907 KACY RER FOR 3/1 IS 5 IN 1980. NOTE: * INDICATE AND OTHER YEARS. NOTE: POR = PERIOD OF RECORD,THE YEAR OFFICIAL CLIMATE OBS BEGAN. THE FOLLOWING IS A TABLE OF THE ***PROJECTED*** TOP 5 COLDEST FEBRUARY`S ON RECORD, BASED ON THE CURRENT FORECAST, AND THUS SUBJECT TO CHANGE. EACH RANKING DENOTES THE MEAN FEBRUARY TEMPERATURE /F/ AND YEAR OF OCCURRENCE. WE REREVIEWED THESE PROJECTIONS LISTED BELOW USING THIS THURSDAY MORNINGS (26TH) MINS AND THE PHI FCST AS SEEN ON NDFD AND SFT`S. WE SEE PHL/ABE/ILG ALL VERY CLOSE TO YESTERDAYS PROJECTIONS. KACY CHANGED TO A WARMER PROJECTION HOWEVER THAT COULD YET REVERT BACK TO A COLDER MONTHLY AVERAGE DUE TO THE POTENTIAL FOR RADIATIONAL COOLING ON ONE OR 2 OF THE MORNINGS. POR / SITE / 1ST RANK / 2ND RANK / 3RD RANK / 4TH RANK / 5TH RANK 1872 / KPHL / 22.2(1934) 23.0(1979) 24.3(1885) 24.6(1978) 25.5(2015) 1874 / KACY / 21.6(1979) 23.8(1978/1934) 24.5(2015) 25.5(1875) 25.7 (1905) 1894 / KILG / 20.2(1934) 22.1(1979) 22.7(1978) 24.5(2015) 24.9(1936) 1922 / KABE / 16.6(1934) 18.9(2015) 20.4(1979) 21.6(1936) 22.0(1963) PER THE ABOVE TABLE, ABE IS EASILY ON TRACK FOR THE SECOND COLDEST FEBRUARY, ATLANTIC CITY 3RD COLDEST FOLLOWED BY THE FOURTH COLDEST AT ILG, AND THE FIFTH COLDEST AT PHL. THE FOLLOWING IS A TABLE OF THE ***PROJECTED*** MEAN FEBRUARY 2015 TEMPERATURES /F/ AND DEPARTURES FROM NORMAL. THIS IS ALSO BASED ON THE CURRENT FORECAST, AND THUS SUBJECT TO CHANGE. JANUARY 2015 MEAN TEMPERATURES ARE ALSO INCLUDED FOR COMPARISON PURPOSES. POR / SITE / FEB MEAN(F) / FEB NORMAL(F) / DEPARTURE / JAN MEAN(F) 1872 / KPHL / 25.5 / 35.7 / -10.2 / 30.9 1874 / KACY / 24.5 / 35.3 / -10.8 / 30.2 1894 / KILG / 24.5 / 35.1 / -10.6 / 30.3 1922 / KABE / 18.9 / 30.7 / -11.8 / 25.9 IN GENERAL, MEAN TEMPERATURES AT OUR FOUR MAJOR CLIMATE SITES ARE ON TRACK TO BE AROUND 10 TO 12 DEGREES BELOW NORMAL FOR FEBRUARY 2015. IT`S ALSO INTERESTING TO NOTE THAT THE PROJECTED FEBRUARY 2015 MEAN TEMPERATURES WILL BE WELL BELOW THE JANUARY 2015 MEAN TEMPERATURES. TO PUT THIS IN PERSPECTIVE, NORMAL MEAN FEBRUARY TEMPERATURES AT OUR FOUR MAJOR CLIMATE SITES ARE ABOUT 2 TO 3 DEGREES WARMER THAN JANUARY. THE OPPOSITE IS SHAPING UP FOR FEBRUARY 2015. ALSO...OF INTEREST...THIS WOULD ALSO BE THE SECOND COLDEST MONTHLY MEAN TEMPERATURE ON RECORD AT ALLENTOWN SINCE RECORDS BEGAN IN 1922; FEBRUARY 1934 BEING THE COLDEST! PHL PROJECTS AROUND 12TH COLDEST MONTHLY MEAN SINCE RECORDS BEGAN IN 1873. ATLANTIC CITY 7TH COLDEST MONTHLY MEAN SINCE RECORDS BEGAN THERE IN 1874. WILMINGTON HAS MISSING DATA IN ITS DATABASE (1897-1916) AND SO WE DON`T FOCUS AS MUCH ATTENTION ON THAT RECORD. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EST THIS AFTERNOON FOR ANZ450>455. && $$ SYNOPSIS...HEAVENER/O`HARA NEAR TERM...JOHNSON SHORT TERM...DRAG/JOHNSON LONG TERM...HEAVENER AVIATION...HEAVENER/JOHNSON MARINE...HEAVENER/JOHNSON CLIMATE...

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.