Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 011423 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 923 AM EST SUN MAR 1 2015 .SYNOPSIS... HIGH PRESSURE LOCATED OVER OUR REGION EARLY THIS MORNING WILL DRIFT OUT TO SEA TODAY. A DEVELOPING COLD FRONT IS FORECAST TO APPROACH FROM THE NORTHWEST AND IT SHOULD PASS THROUGH OUR AREA EARLY ON MONDAY MORNING. HIGH PRESSURE IS EXPECTED TO FOLLOW FOR MONDAY AFTERNOON INTO EARLY TUESDAY. LOW PRESSURE IS ANTICIPATED TO MOVE ACROSS THE GREAT LAKES ON TUESDAY AFTERNOON AND TUESDAY EVENING, THEN DOWN THE SAINT LAWRENCE RIVER VALLEY FROM LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. THE LOW IS FORECAST TO PULL A COLD FRONT SLOWLY THROUGH OUR REGION ON WEDNESDAY. WEAK LOW PRESSURE IS EXPECTED TO RIDE ALONG THE FRONT ON THURSDAY BEFORE HIGH PRESSURE BUILDS INTO OUR AREA FROM THE WEST FOR FRIDAY INTO SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SNOW HAS ARRIVED ACROSS THE WESTERN COUNTIES AND IT WILL CONTINUE TO OVERSPREAD THE AREA. THE PRECIP ACROSS THE DELMARVA WILL BEGIN AS SNOW BUT WILL CHANGE TO SLEET SOON AFTER. WE MAY HAVE TO RECONSIDER P-TYPE QPF AMTS OVER THE DELMARVA FOR POSSIBLE WSW UPGRADE. LOW/MID- LEVEL MOISTURE IS INCREASING ACROSS THE AREA, AN AREA OF ENHANCED LIFT SLIDES ACROSS THE AREA. TEMPERATURES AT THE SURFACE AND ALOFT WILL BE COLD ENOUGH FOR THE PRECIPITATION TO START OUT AS SNOW ACROSS THE AREA. HOWEVER, AS WARM AIR ABOVE THE SURFACE MOVES IN THROUGH THE DAY, PRECIPITATION WILL CHANGE OVER TO SLEET THEN FREEZING RAIN ACROSS MUCH OF THE AREA. THIS OCCURS WHEN THE HEAVIEST PRECIPITATION IS EXPECTED TO MOVE INTO THE AREA AS WELL. WE ARE BECOMING MORE CONCERNED WITH THE POTENTIAL FOR MORE ICE TO OCCUR ACROSS PORTIONS OF OUR AREA, ESPECIALLY THE I-95/I-295 CORRIDOR. FOR THESE AREAS, ICE AMOUNTS OF 1/4-1/3 OF AN INCH OF ICE IS POSSIBLE, ALONG WITH AN INCH OR TWO OF SNOW/SLEET. THEREFORE, WE HAVE UPGRADED THESE AREAS TO A WINTER STORM WARNING DUE TO THE INCREASED ICE EXPECTATION. AREAS TO THE SOUTH AND NORTH OF THE WARNING ARE EXPECTED TO GET UP TO 1/10-2/10 OF AN INCH OF ICE ALONG WITH AN INCH OF SNOW FOR SOUTHERN AREAS AND 3-4 INCHES FOR NORTHERN AREAS. THE EXCEPTIONS TO THIS WOULD BE ACROSS FAR SOUTHERN DELAWARE WHERE JUST A FEW HUNDREDTHS OF AN INCH OF ICE AND A LIGHT DUSTING OF SNOW MAY OCCUR AND FAR NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY WHERE THEY WILL LIKELY REMAIN ALL SNOW AND GET 4-5 INCHES OF SNOW. THE WINTER WEATHER ADVISORY REMAINS IN PLACE FOR ALL AREAS OUTSIDE OF THE WINTER STORM WARNING. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... THE WINTER STORM WARNINGS/WINTER WEATHER ADVISORIES REMAIN IN PLACE ACROSS THE AREA INTO THIS EVENING AS WINTRY PRECIPITATION IS EXPECTED TO BE ONGOING; THE ONLY CHANGE WAS TO ADJUST THE END TIME FOR THE SOUTHERN AREAS. AS A DEVELOPING FRONTAL BOUNDARY MOVES ACROSS THE AREA OVERNIGHT, THE ENHANCED LOW/MID-LEVEL MOISTURE AND LIFT WILL BE MOVING TO OUR EAST AS WELL. PRECIPITATION IS EXPECTED TO COME TO AN END FROM WEST TO EAST DURING THE OVERNIGHT HOURS AND ALL PRECIPITATION SHOULD BE ENDING BETWEEN MIDNIGHT AND DAYBREAK. && .LONG TERM /MONDAY THROUGH SATURDAY/... IT CONTINUES TO APPEARS AS THOUGH WE WILL SEE A BREAK IN THE PRECIPITATION FOR MONDAY INTO EARLY TUESDAY AS HIGH PRESSURE FROM THE WEST BUILDS ACROSS OUR REGION. A GUSTY NORTHWEST WIND IS ANTICIPATED FOR MONDAY AND TEMPERATURES SHOULD REMAIN ABOUT 10 DEGREES BELOW NORMAL FOR MONDAY AND MONDAY NIGHT. HIGH CLOUDS SHOULD BEGIN TO OVERSPREAD OUR REGION FROM THE WEST AND SOUTHWEST LATE ON MONDAY NIGHT. MID LEVEL CLOUDS ARE FORECAST TO FOLLOW ON TUESDAY MORNING. PRECIPITATION IS EXPECTED TO ARRIVE IN OUR REGION FOR TUESDAY AFTERNOON. THE FORECAST TEMPERATURE PROFILES SUGGEST A MIX OF SNOW AND SLEET AT THE START, EXCEPT PERHAPS IN OUR FAR SOUTH WHERE THE PRECIPITATION MAY BEGIN AS RAIN. STRONG WARM ADVECTION IS EXPECTED TO TAKE PLACE ALOFT FROM TUESDAY AFTERNOON INTO TUESDAY EVENING. A TRANSITION FROM MIXED PRECIPITATION TO RAIN WILL LIKELY WORK ITS WAY NORTHWARD THROUGH OUR REGION. THE PRECIPITATION TYPE IS FORECAST TO BECOME RAIN ALONG THE INTERSTATE 95 CORRIDOR DURING THE EVENING HOURS. THE MIX OF SNOW AND ICE SHOULD LINGER INTO THE OVERNIGHT HOURS IN OUR FAR NORTHERN COUNTIES. HOWEVER, EVEN THE POCONOS AND SUSSEX COUNTY, NEW JERSEY SHOULD TRANSITION TO RAIN BY DAYBREAK ON WEDNESDAY AS TEMPERATURES RISE GRADUALLY THROUGHOUT OUR REGION ON TUESDAY NIGHT. SNOWFALL TOTALS IN OUR NORTHERN COUNTIES SHOULD BE SOMEWHAT LIMITED DUE TO THE MIX OF SLEET AND FREEZING RAIN. ICING MAY BE THE MORE SIGNIFICANT PROBLEM THERE. THE RAIN MAY BECOME MODERATE TO HEAVY AT TIMES. THE 0000 UTC RUN OF THE NAM IS BRINGING FROM A HALF INCH TO AN INCH TO OUR REGION FROM LATE TUESDAY INTO TUESDAY NIGHT. THE 0000 UTC GFS HAS A RANGE OF AN INCH TO AN INCH AND A HALF. THE 0000 UTC ECMWF IS A BIT LOWER THAN THE NAM. BEING THE THE GFS HAS BEEN RUNNING HIGH IN ITS PRECIPITATION FORECASTS OF LATE, WE WILL FAVOR THE NAM/ECMWF SOLUTION. SNOW MELT ALONG WITH ICE MOVEMENT ON AREA WATERWAYS COULD COMBINE WITH THE RAINFALL TO CREATE SOME FLOODING ISSUES. THE POTENTIAL IS ADDRESSED IN THE HYDROLOGY SECTION OF THE FORECAST DISCUSSION. A COLD FRONT IS FORECAST TO MOVE SLOWLY THROUGH OUR REGION ON WEDNESDAY AND ITS PROGRESS MAY BE SLOWED BY A WAVE OF LOW PRESSURE RIDING ALONG THE BOUNDARY. AS A RESULT, CLOUDS AND PRECIPITATION MAY LINGER THROUGH WEDNESDAY NIGHT AND INTO THURSDAY, ESPECIALLY IN OUR SOUTHERN COUNTIES. THERE COULD BE ADDITIONAL MODERATE RAINFALL ACROSS THE SOUTH ON WEDNESDAY AND THE PRECIPITATION MAY BEGIN TO CHANGE BACK TO SNOW, MAINLY IN THE NORTH FROM WEDNESDAY NIGHT INTO THURSDAY. ANOTHER ARCTIC HIGH IS EXPECTED TO BUILD ACROSS OUR REGION FROM THE WEST AND NORTHWEST FOR FRIDAY INTO SATURDAY. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TAFS ARE ALL VFR THIS MORNING, BUT THIS WILL CHANGE THROUGH THE DAY. CLOUDS WILL INCREASE AND THICKEN THROUGH THE MORNING, AND EVENTUALLY BECOME MVFR AS LIGHT SNOW MOVES INTO THE AREA BY MIDDAY. AS THE SNOW CONTINUES, CIGS AND VSBYS ARE EXPECTED TO LOWER TO IFR. PRECIPITATION IS EXPECTED TO CHANGE OVER TO SLEET THEN FREEZING RAIN BY THIS AFTERNOON AND CONTINUE INTO THE NIGHT. IFR CONDITIONS WILL PERSIST INTO THE OVERNIGHT, BEFORE POSSIBLY IMPROVING TO MVFR BY DAYBREAK. WINDS ARE FAIRLY LIGHT AND VARIABLE THIS MORNING, BUT WILL BECOME MORE SOUTHEAST-SOUTH THROUGH THE MORNING INTO THE AFTERNOON INTO THE EVENING. AS A FRONTAL BOUNDARY APPROACHES THEN MOVES THROUGH THE AREA OVERNIGHT, WINDS WILL BECOME SOUTHWEST-WEST. ALL SPEEDS ARE EXPECTED TO REMAIN BELOW 10 KNOTS THROUGH TONIGHT, BEFORE INCREASING TOWARD DAYBREAK MONDAY. OUTLOOK... MONDAY...CONDITIONS IMPROVING TO VFR IN THE MORNING. MONDAY NIGHT...MAINLY VFR. TUESDAY...CONDITIONS LOWERING TO MVFR AND IFR IN THE AFTERNOON, AS SNOW AND SLEET BUILD INTO OUR REGION. TUESDAY NIGHT...MVFR AND IFR CONDITIONS WITH A WINTRY MIX OF PRECIPITATION CHANGING TO RAIN FROM SOUTH TO NORTH. THE RAIN MAY BE MODERATE TO HEAVY AT TIMES. LOW LEVEL WIND SHEAR IS POSSIBLE DUE TO A SOUTHWESTERLY LOW LEVEL JET THAT IS FORECAST TO DEVELOP OVERHEAD. WEDNESDAY...MVFR AND IFR CONDITIONS IN RAIN. THE RAIN MAY BE MODERATE TO HEAVY AT TIMES, ESPECIALLY SOUTH OF KPHL. WEDNESDAY NIGHT...MVFR AND IFR CONDITIONS IN RAIN, POSSIBLY MIXING WITH OR CHANGING TO SNOW TO THE NORTH OF KPHL. THURSDAY...CONDITIONS IMPROVING GRADUALLY TO VFR WITH A LESSING CHANCE OF PRECIPITATION THROUGH THE DAY. && .MARINE... SUB-SMALL CRAFT ADVISORY CONDITIONS CONTINUE TODAY ACROSS THE WATERS AS HIGH PRESSURE PULLS TO OUR EAST. WINDS DO INCREASE AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THE HIGH AND AN APPROACHING FRONTAL BOUNDARY. HOWEVER, THEY DO NOT INCREASE TO ADVISORY LEVELS UNTIL DAYBREAK MONDAY BEHIND THE FRONTAL BOUNDARY. OUTLOOK.. MONDAY AND MONDAY NIGHT...A SMALL CRAFT ADVISORY IS IN EFFECT DUE TO THE EXPECTED GUSTY NORTHWEST WIND. LIGHT FREEZING SPRAY IS POSSIBLE, ESPECIALLY ON MONDAY NIGHT. TUESDAY...NO MARINE HEADLINES ARE ANTICIPATED. TUESDAY NIGHT AND WEDNESDAY...A SMALL CRAFT ADVISORY MAY BE NECESSARY DUE TO A GUSTY SOUTH TO SOUTHWEST WIND. WEDNESDAY NIGHT AND THURSDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .HYDROLOGY... TWO PRECIPITATION EVENTS ARE EXPECTED OVER THE NEXT 5 DAYS, ONE TODAY INTO TONIGHT AND A SECOND ONE DURING THE MID WEEK PERIOD. THE INITIAL EVENT LOOKS TO BE ONE WITH A WINTRY MIX OF PRECIPITATION. THE SECOND EVENT APPEARS TO BE MAINLY RAIN WITH TEMPERATURES RISING WELL ABOVE FREEZING ON WEDNESDAY. ALTHOUGH THE SECOND EVENT IS A FEW DAYS AWAY, WE WANT TO HIGHLIGHT THAT SOME OF THE MODEL GUIDANCE IS SUGGESTING LOCALLY HEAVY RAINFALL. THE COMBINATION OF A BRIEF WARM-UP ON WEDNESDAY, LOCALLY HEAVY RAINFALL, MELTING SNOW, A FROZEN GROUND, AND ABOVE NORMAL ICE IN CREEKS, STREAMS, AND RIVERS COULD LEAD TO INCREASED RUNOFF AND POSSIBLE FLOODING. WHERE THE DEPTH OF THE SNOWPACK IS GREATEST (IN NE PA AND N NJ), RAPID SNOWMELT IS NOT EXPECTED SINCE TEMPS WILL NOT RISE AS SHARPLY AS IN AREAS TO THE SOUTH. INCREASED FLOW 0N AREA CREEKS, STREAMS, AND RIVERS COULD ALSO START TO MOVE ICE, AND IN A WORST CASE SCENARIO, CREATE RESTRICTIONS OR JAMS. AGAIN, THE SECOND EVENT BRINGING WARMTH AND RAIN IS A FEW DAYS AWAY AND THINGS CAN CHANGE. CONTINUE TO MONITOR THE FORECAST. KEEP IN MIND THAT SNOWMELT AND WARMTH BY THEMSELVES TYPICALLY DO NOT CAUSE FLOODING. THE AMOUNT OF RAIN THAT WE RECEIVE WILL BE THE DETERMINING FACTOR. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST MONDAY FOR PAZ054-055- 060>062-105. WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR PAZ070-071- 101>104-106. NJ...WINTER WEATHER ADVISORY UNTIL 4 AM EST MONDAY FOR NJZ001- 007>010. WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR NJZ014-021- 022-025-026. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR NJZ023-024. WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR NJZ012-013- 015>020-027. DE...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR DEZ002. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR DEZ003-004. WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR DEZ001. MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR MDZ015. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ019-020. WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR MDZ008-012. MARINE...SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 2 AM EST TUESDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...IOVINO NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...IOVINO AVIATION...IOVINO/ROBERTSON MARINE...IOVINO/ROBERTSON HYDROLOGY...

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