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 280231 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 931 PM EST TUE JAN 27 2015 .SYNOPSIS...
-- Changed Discussion --
A STRONG STORM SYSTEM EAST OF NEW ENGLAND TONIGHT WILL REACH THE CANADIAN MARITIMES ON WEDNESDAY. HIGH PRESSURE WILL MOVE IN FROM THE OHIO VALLEY WEDNESDAY AND SETTLE OVER THE REGION WEDNESDAY NIGHT AND THURSDAY MORNING. LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY AND REFORM EAST OF NEW ENGLAND ON FRIDAY. HIGH PRESSURE WILL MOVE IN FROM THE GREAT LAKES ON SATURDAY...FOLLOWED BY A LOW PRESSURE SYSTEM MOVING THROUGH THE APPALACHIANS EARLY NEXT WEEK.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
A COLD, BREEZY NIGHT WILL CONTINUE ACROSS THE AREA TONIGHT. MOSTLY MID/HIGH LEVEL CLOUD COVER IS EXPECTED OVERNIGHT AS THE STORM PULLS FARTHER AWAY TO THE NORTHEAST. NORTHWEST WINDS AROUND 15-20 MPH WILL CONTINUE WITH GUSTS AROUND 25-30 MPH AT TIMES. THE FRESH SNOW COVER UP NORTH SHOULD ALLOW TEMPERATURES TO DROP INTO THE SINGLE DIGITS. LOWS IN THE MID-TEENS TO AROUND 20 ARE EXPECTED FURTHER SOUTH WERE THE SNOW COVER ISN/T AS DEEP OR WIDESPREAD. A BLEND OF MAV/MET GUIDANCE WAS USED FOR OVERNIGHT TEMPERATURES, UNDERCUT BY A DEGREE OR TWO UP NORTH TO ACCOUNT FOR SNOW COVER. THE COLD TEMPERATURES COMBINED WITH THE STRONG WINDS WILL CREATE WIND CHILL VALUES IN THE SINGLE DIGITS TO SINGLE DIGITS BELOW ZERO FOR MOST AREAS, AND CLOSE TO -10 TO -15 FOR THE HIGHER ELEVATIONS OF CARBON/MONROE, PA AND SUSSEX, NJ.
-- End Changed Discussion --
&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... MOSTLY SUNNY CONDITIONS ARE EXPECTED...EXCEPT FOR MORNING CLOUDINESS IN NORTHERN NJ (LINGERING EFFECTS FROM THE DEPARTING LOW). NORTHWEST WINDS WILL PICKUP ONCE AGAIN AS DAYTIME MIXING TAKES PLACE...THEN GRADUALLY DECREASE LATE IN THE DAY AS THE SUN BEGINS TO SET AND AS THE PRESSURE GRADIENT CONTINUES TO DECREASE. TEMPS ARE EXPECTED TO MAX OUT IN THE LOW TO MID 20S FAR NORTH, AND IN THE LOW 30S SOUTH. AGAIN...A BLEND OF MAV/MET GUIDANCE WAS USED FOR HIGH TEMPERATURES WITH A SLIGHT CUT IN THE LOCATIONS OF DEEPER SNOWPACKS. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... THE MID LEVEL PATTERN AT 00Z THU IS COMPRISED OF A DEEP TROUGH AT 70W WITH A NORTHERN STREAM RIDGE ALONG THE BRITISH COLUMBIA COAST AND A SOUTHERN STREAM CLOSED LOW INVOF THE CALIFORNIA COAST. BETWEEN THESE TWO FEATURES...S/WV RIDGE WILL CREST OVER THE MID ATL ON THU...THEN NORTHERN AND SOUTHERN STREAM S/WV ENERGY IS PROGGED TO PHASE INVOF THE MISSISSIPPI VALLEY AND BECOME NEG TILTED AS IT REACHES 70W AROUND 00Z SAT. THIS LEADS TO LOW PRESSURE MOVING THRU THE GREAT LAKES ON THU WITH REDEVELOPMENT CURRENTLY MODELED INVOF GEORGES BANK ON FRI. BY SAT...NORTHERN STREAM S/WV ENERGY ENTERING THE NORTHERN PLAINS IS EXPECTED TO INTERACT WITH SOUTHERN STREAM S/WV ENERGY EJECTING OUT OF A CLOSED LOW INVOF THE FOUR CORNERS REGION. THIS LEADS TO A COMPLEX AREA OF LOW PRESSURE...WHICH IS CURRENTLY PROGGED TO MOVE THRU THE APPALACHIANS EARLY NEXT WEEK. THE BEST CHANCES FOR PRECIP IN THE LONG TERM WILL BE THU NIGHT INTO EARLY FRI AND THEN AGAIN EARLY NEXT WEEK...WITH PTYPE ISSUES LIKELY WITH BOTH SYSTEMS...AS TEMPERATURES ROLLER COASTER FROM NEAR NORMAL TO WELL BELOW NORMAL THROUGHOUT THE PERIOD. DETAILS... WED NIGHT AND THU... GENERALLY TRANQUIL WEATHER AS A RIDGE OF HIGH PRES CRESTS OVER THE REGION. EXPECTING IDEAL CONDITIONS FOR RADIATIONAL COOLING THU AM AS ATMOS DECOUPLES WITH CLEAR SKIES...LIGHT WINDS...AND FRESH SNOW COVER. EXPECTING MIN TEMPS 10 TO 15 DEGREES BELOW NORMAL REGION- WIDE. ON THU LARGE SCALE FLOW BECOMES SOUTHWEST AND MODEL X-SECS INDICATE MID LEVEL MOISTURE STREAMING INTO THE REGION...ESPECIALLY IN THE AFTN. THE GFS AND CANADIAN ARE MOST AGGRESSIVE IN BRINGING PRECIP IN PRIOR TO 00Z ALONG AND WEST OF THE DE RIVER...AND THIS TIMING IS REFLECTED IN THE FCSR. MAX TEMPS WILL GENERALLY BE 5 TO 10 DEGREES BELOW NORMAL. THU NIGHT THRU FRIDAY NIGHT... LOW PRESSURE MOVES THRU THE SAINT LAWRENCE VALLEY WITH GOOD MODEL AGREEMENT ON THE STRONGEST DYNAMICS JUST TO THE NORTH AND WEST... AND THUS RESULTANT QPF BULLSEYE. ATTM...MODEL QPF IS GENERALLY A TRACE OVER THE DELMARVA TO 0.2 INCHES OVER THE FAR NORTHWEST. THE GREATEST UNCERTAINTY IS IN MODEL THERMAL PROFILES AND THUS PTYPE. THIS DOES NOT APPEAR TO BE A COLD AIR DAMMING SITUATION WITH HIGH PRES OFFSHORE AND THE ABSENCE OF AN INVERSION. NEVERTHELESS...LOW PRES WELL NORTHWEST WILL LEAD TO BOUNDARY LAYER WINDS INSUFFICIENT FOR WARM AIR ADVECTION. MODEL SOUNDINGS INDICATE A RAIN/SNOW EVENT WITH CURRENT PROFILES CONFINING RAIN TO SOUTHEAST NJ...DE...AND MD WHERE MODEL QPF IS LIGHTEST. EXPECTING SNOW-LIQUID RATIOS RANGING FROM 5:1 TO 10:1 WHICH WOULD GIVE ACCUMULATIONS UP TO 1 INCH INVOF I-95 TO 3 INCHES OVER THE NORTHWEST...BUT THIS IS PRELIMINARY... STAY TUNED. PRECIP ENDS EARLY FRI WITH STRONG COLD AIR ADVECTION AS LOW PRESSURE REDEVELOPS EAST OF NEW ENG...AS TEMPS FALL THRU THE DAY AFTER MORNING MAXS. THERE IS ALSO THE POTENTIAL FOR SNOW SQUALLS...PARTICULARLY OVER THE POCONOS...WITH A COLD FRONTAL PASSAGE FRI AFTN. MODEL SOUNDINGS SHOW MIXING TO 850 HPA WITH POTENTIAL FOR WIND GUSTS AROUND 30 KNOTS. THE COMBINATION OF BLUSTERY WINDS AND BELOW NORMAL TEMPERATURES ON FRIDAY NIGHT WILL LEAD TO LOW WIND CHILLS...THEREFORE...A WIND CHILL ADVISORY MAY EVENTUALLY BE NEEDED. SAT AND SUN... MID-LEVEL CYCLONIC FLOW OVER THE REGION ON SAT GRADUALLY GIVES WAY TO BRIEF RIDGING ON SUN. ON SAT THE COLUMN WILL DRY OUT...ASIDE FOR POSSIBILITY OF STRATOCUMULUS BENEATH A MODELED SUBSIDENCE INVERSION...WITH ONE LAST BRISK DAY IN NORTHWEST FLOW BEHIND DEPARTING LOW. MID LEVEL FLOW ON SUNDAY BECOMES SOUTHWEST...AND THE COLUMN WILL GRADUALLY MOISTEN IN ADVANCE OF STORM SYSTEM TO THE SOUTHWEST. TEMPS EXPECTED TO BE 10 TO 15 DEGREES BELOW NORMAL. SUNDAY NIGHT THRU TUESDAY... COMPLICATED FORECAST AS LOW PRESSURE TRAVERSES THE APPALACHIANS LATE SUNDAY INTO EARLY MONDAY. STRONG MID-LEVEL VORT MAX APPROACHES THE COAST WITH DUAL JET SETUP FAVORING REDEVELOPMENT INVOF MID ATL OR NEW ENGLAND. ATTM...THERMAL PROFILES GENERALLY FAVOR SNOW WITH RAIN MIXING IN CLOSER TO THE COAST...BUT THIS IS HIGHLY UNCERTAIN. REDEVELOPMENT COULD LEAD TO COLDER AIR BEING DRAWN IN...WHICH WOULD BRING SNOW FURTHER SOUTH ALONG THE COAST. ANY WINTER WX WOULD BE EXACERBATED BY COLD ANTECEDENT CONDITIONS...MAKING SURFACES MORE PRONE TO ICING. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED OVERNIGHT FOR ALL TAF SITES. THERE MAY BE SOME LINGERING SCATTERED LOWER CLOUDS AROUND, BUT WE EXPECT MOSTLY MID/UPPER LEVEL CLOUDS THROUGH THE NIGHT. SUSTAINED WINDS WILL CONTINUE AROUND 10-15 KNOTS, WITH IN AND OUT GUSTS AROUND 20-25 KNOTS INTO THE EARLY PART OF THE NIGHT. FREQUENT GUSTS SHOULD DROP OFF DURING THE NIGHT AS MIXING WEAKENS, BUT THERE COULD STILL BE OCCASIONAL GUSTS. WEDNESDAY WILL BE A VFR DAY WITH FREQUENT NORTHWEST GUSTS AGAIN AROUND 20-25 KNOTS. GUSTS WILL AGAIN DECREASE AFTER SUNSET. OUTLOOK... WEDNESDAY NIGHT...PRIMARILY VFR. THURSDAY INTO FRIDAY MORNING...PRIMARILY VFR FOR MUCH OF THU. LIGHT SNOW IS EXPECTED TO OVERSPREAD THE AREA FROM WEST TO EAST THU NIGHT BUT MAY REACH ABE/RDG BY LATE AFTERNOON. MVFR/IFR POSSIBLE WITH THE SNOW. HIGHEST CONFIDENCE IS AT NORTHERN TERMINALS. FRIDAY AFTERNOON...VFR WITH NW WINDS GUSTING AROUND 30 KT. FRI NIGHT...VFR WITH GUSTY NW WINDS EXPECTED TO CONTINUE. SATURDAY...VFR. SUNDAY...LIGHT SNOW IS EXPECTED TO OVERSPREAD THE AREA FROM WEST TO EAST DURING THE DAY...LOW CONFIDENCE ON TIMING. MVFR/IFR POSSIBLE WITH THE SNOW.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
GALE WIND GUSTS HAVE TAPERED OFF IN CONJUNCTION WITH THE DEPARTING LOW PRESSURE SYSTEM. HOWEVER, ON THE BACKSIDE OF THE LOW PRESSURE STRONG NORTHWEST WINDS WITH SCA GUSTS WILL LIKELY CONTINUE TILL AROUND 18Z WEDNESDAY IN ALL MARINE ZONES, WITH SOME SCATTERED SCA GUSTS THROUGH 23Z. WAVE HEIGHTS WILL GRADUALLY DECREASE BY WEDNESDAY AFTERNOON TO AROUND FIVE FEET. SCA REMAINS THROUGH 23Z WEDNESDAY ON THE OCEAN, AND 18Z ON THE BAY. OUTLOOK... WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...NO MARINE HEADLINES ARE ANTICIPATED. SOME FREEZING SPRAY POSSIBLE WEDNESDAY NIGHT. FRIDAY...NEAR GALE-FORCE NW GUSTS BEHIND DEPARTING LOW PRESSURE. FRIDAY NIGHT...POSSIBLE LEFTOVER NW GALE FORCE GUSTS. FREEZING SPRAY LIKELY. SATURDAY...SCA CONDITIONS POSSIBLE. FREEZING SPRAY POSSIBLE... ESPECIALLY EARLY. SUNDAY...CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA THRESHOLDS.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR ANZ430-431.
-- End Changed Discussion --
&& $$ SYNOPSIS...FRANCK NEAR TERM...ROBERTSON/MIKETTA SHORT TERM...MIKETTA LONG TERM...FRANCK AVIATION...FRANCK/GAINES/ROBERTSON MARINE...FRANCK/GAINES

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