Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201509 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1009 AM EST SAT DEC 20 2014 .SYNOPSIS... HIGH PRESSURE REMAINS OVER THE REGION THIS WEEKEND INTO MONDAY. A WAVE OF LOW PRESSURE WEAKENS AS IT APPROACHES MONDAY NIGHT INTO TUESDAY. A MORE SIGNIFICANT STORM SYSTEM THEN AFFECTS THE AREA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...WITH ITS EFFECTS STILL FELT ON THURSDAY. HIGH PRESSURE BUILDS IN ON FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A FEW MINOR ADJUSTMENTS MADE BASED ON CURRENT CONDITIONS. THERE IS A BREAK IN THE CLOUD COVER ACROSS SW CT WHICH IS FILLING BACK IN. HIGH PRESSURE TO THE NORTH SHIFTS EAST TOWARD MAINE. THE MAIN FORECAST CHALLENGE TODAY WILL BE THE AMOUNT OF CLOUD COVER AS MOISTURE IS BEING TRAPPED UNDER A STRONG INVERSION NEAR 900MB. MODELS ARE IN GENERAL AGREEMENT THAT MOISTURE INCREASES BELOW THIS DURING THE AFTERNOON. WILL GO WITH A PARTLY TO MOSTLY CLOUDY FORECAST. QPF OUTPUT ALSO INDICATES VERY LIGHT PCPN CHANCES OVER THE FORKS REGION/SE CT TOWARDS SUNSET...BUT WILL MAINTAIN A DRY FORECAST FOR THE DAYTIME. MAV/NAM MOS BLEND LOOKED GOOD FOR HIGH TEMPS. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... WE WILL HAVE A CHANCE OF PCPN FOR SOME AREAS TONIGHT...BUT VERY LIGHT. DURING THE EVENING...WEAK LIFT...MAINLY OVER THE EASTERN AREAS...WILL BE SUPPLIED BY A SHORTWAVE IN THE LOW-MID LEVELS. THIS COMBINED WITH LOW LEVEL MOISTURE IN PLACE WILL BRING A CHANCE OF FLURRIES/LIGHT SNOW OVER LONG ISLAND AND SE CT. THEN FOR THE OVERNIGHT HOURS...CHANCES OF FLURRIES/LIGHT SNOW SPREAD WEST WITH LOW LEVEL MOISTURE ADVECTION AND INCREASING PVA FROM THE WEST. THINKING IS THAT PCPN TYPE WOULD FAVOR FLURRIES/LIGHT SNOW OVER DRIZZLE IN SPITE OF MOISTURE LACKING IN THE MID LEVELS. LOOKS LIKE COLDEST TEMPS IN THE SATURATED LAYER BENEATH THE LOW LEVEL INVERSION WILL BE COLD ENOUGH TO SUPPORT ICE CRYSTALS. BOUNDARY LAYER TEMPS WOULD ALSO TEND TO FAVOR FLURRIES/LIGHT SNOW. MID LEVEL SHORTWAVE PASSES THROUGH SUNDAY MORNING WITH FLURRIES/DRIZZLE POSSIBLE...THEN NVA BEHIND IT AND DEEP-LAYERED RIDGING LIKELY PREVENTS PCPN IN THE AFTERNOON. HIGH TEMPS NEAR NORMAL. DRY WEATHER CONTINUES INTO SUNDAY NIGHT WITH HIGH PRESSURE RIDGING. && .LONG TERM /MONDAY THROUGH SATURDAY/... WEAK LOW PRESSURE FORMS ALONG A FRONTAL BOUNDARY OFF THE CAROLINA COAST ON MONDAY AND BEGINS TO HEAD NORTH. MEANWHILE...HIGH PRESSURE CENTERED TO THE NORTHEAST SHIFTS FARTHER EAST. THIS WILL LOW LEVEL WINDS HERE VEER TO THE EAST AND AID LOW LEVEL MOISTURE ADVECTION. A SURFACE TROUGH EXTENDING NORTH FROM THE CENTER OF THE LOW WILL SERVE AS A FOCUS FOR WEAK LIFT AND MOISTURE CONVERGENCE. LOW CHANCES OF LIGHT RAIN RESULT...BUT BETTER OVERALL CHANCES OCCUR DURING THE AFTERNOON. THE LOW CENTER WEAKENS AS IT HEADS NORTH MONDAY NIGHT AND TUESDAY. HOWEVER...ISENTROPIC LIFT AHEAD OF THE LOW STILL STRENGTHENS...LOW LEVEL MOISTURE STILL INCREASES ON AN ENE FLOW...AND THE SURFACE TROUGH WILL STILL BE IN THE VICINITY. POPS FOR TUESDAY MIGHT BE A LITTLE TOO HIGH...BUT THEY ARE STILL REASONABLE...AND CURRENTLY DO NOT HAVE THE CONFIDENCE TO LOWER POPS FROM THE CURRENT LOW-END LIKELY. BETTER OVERALL CHANCES OF RAIN OCCUR IN THE AFTERNOON. PCPN TYPE IS RAIN...EXCEPT A MIX OF RAIN AND SNOW LATE MON NIGHT AND TUES MORNING FOR THE NORTHERN FRINGE ZONES. MIGHT NEED TO MONITOR FOR THE POSSIBILITY OF MINOR COASTAL FLOODING STARTING WITH TUESDAY MORNING`S HIGH TIDE CYCLE AS A PERSISTENT EASTERLY FLOW STRENGTHENS. A STRONGER STORM SYSTEM THEN AFFECTS US CHRISTMAS EVE AND DAY. MODELS SHOW A STRONG PRIMARY LOW CENTER MOVING THROUGH THE GREAT LAKES REGION ON WEDNESDAY BEFORE MOVING INTO ONTARIO ON THURSDAY. A WEAKER SECONDARY LOW PRESSURE CENTER OR TRIPLE POINT LOW FORMS IN THE MID ATLANTIC REGION BEFORE PASSING OVER OR JUST NORTH OF US WEDNESDAY NIGHT. THIS WILL DRAG A COLD FRONT ACROSS THE AREA DURING THE NIGHT. CATEGORICAL POPS FOR WEDS/WEDS EVENING BEFORE THE COLD FRONT MOVES THROUGH...THEN JUST LOW CHANCES OF SHOWERS AFTER MIDNIGHT...MAINLY EAST OF THE CITY. RAINFALL EXPECTED TO BE MOSTLY ON THE MODERATE SIDE WITH MINOR URBAN FLOODING POSSIBLE. FOR THURSDAY...A STRONG FETCH OFF OF LAKE ERIE COULD BRING A RAIN OR SNOW SHOWER TO THE FAR NW PORTION OF THE CWA THURSDAY MORNING. BREEZY CONDITIONS FOR WEDS THRU THURS. A STRONG LOW LEVEL JET PUSHES THROUGH THE EASTERN ZONES WEDS AFTN/EVE...BUT STRONG GUSTS WILL PROBABLY HAVE A TOUGH TIME MIXING DOWN THROUGH AN INVERSION. STRONGER GUSTS MAY BE REALIZED DURING THURSDAY BEHIND THE COLD FRONT COURTESY OF BETTER MIXING. MARGINAL ADVISORY CRITERIA GUSTS COULD BE POSSIBLE WEDS AFTN THRU THURS. TEMPS DURING THIS PERIOD WILL BE ABOVE AVERAGE. HIGHS ON WEDS IN THE 50S...AND WITH A MODERATE WSW FLOW AND PARTIAL SUNSHINE ON THURSDAY...HIGH TEMPS WELL INTO THE 40S EXPECTED. HIGH PRESSURE BUILDS IN FOR FRIDAY WITH LIGHTER WINDS AND CLOSER TO NORMAL TEMPERATURES. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE BUILDS OVER THE AREA FOR THIS WEEKEND AND DEPARTS EARLY IN THE NEW WEEK. CIGS WILL VARY BETWEEN SCT-BKN 2500-3500 FT AS MOISTURE REMAINS TRAPPED UNDER AN INVERSION. BEST CHANCES FOR VFR CIGS WILL OCCUR THIS AFTERNOON. INCREASING CHANCES FOR WIDESPREAD BKN-OVC MVFR CIGS 2500-3000 FT TONIGHT. N TO NE WINDS AT 6-8 KT TODAY WILL BECOME LGT/VRB LATE THIS AFTERNOON AND THROUGH TONIGHT. LIGHT SNOW AND/OR FLURRIES POSSIBLE FOR KGON/KISP AFTER MIDNIGHT TONIGHT. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .SUNDAY...MVFR CIGS...WITH LIGHT SNOW/RAIN SHOWERS POSSIBLE FOR CITY/COASTAL TERMINALS. LIGHT NORTHEAST WINDS. .MON...MVFR OR LOWER POSSIBLE IN E-SE FLOW. CHC OF RAIN. .MON NIGHT-TUE...IFR LIKELY AT TIMES IN RAIN...CIGS AND VSBYS. E-SE WINDS 10-20 KT. .TUE NIGHT AND WED...HIGH IMPACT EVENT POSSIBLE...IFR LIKELY WITH HEAVY RAIN AND GUSTY SE WINDS 25KT+ SHIFTING TO SW LATE WED. && .MARINE... WITH HIGH PRES BUILDING OVER THE WATERS...CAN EXPECT NORTH WINDS 10 KT OR LESS THROUGH THE WEEKEND ALONG WITH SEAS GENERALLY 1-2 FT ON THE OCEAN OR 1 FT OR LESS ON ALL OTHER WATERS. EASTERLY FLOW DEVELOPS ON MONDAY AS LOW PRES PASSES SOUTH OF THE WATERS EARLY IN THE NEW WEEK. SMALL CRAFT ADVISORY CONDS DEVELOP ON TUESDAY AS GRADIENT TIGHTENS. ANOTHER LOW DEVELOPS OVER THE MID-ATLANTIC AREA AND TRACKS NORTH THROUGH THE WATERS WEDNESDAY AND WEDNESDAY NIGHT. THAT LOW RAPIDLY DEEPENS OVER CANADA ON THURSDAY... ALLOWING THE GRADIENT TO TIGHTEN OVER THE WATERS. SMALL CRAFT ADVISORY CONDS EXPECTED THROUGH WEDNESDAY...AND THEN GALES ARE LIKELY THURSDAY AND THURSDAY NIGHT. && .HYDROLOGY... NO HYDRO IMPACTS EXPECTED INTO EARLY NEXT WEEK. AROUND A QUARTER INCH OF RAIN IS POSSIBLE IS POSSIBLE MONDAY AFTERNOON THROUGH TUESDAY AS LOW PRES PASSES SOUTH OF LONG ISLAND. NO HYDROLOGICAL IMPACTS EXPECTED. RAIN ON WED/WED NIGHT MAY AVERAGE 1-2 INCHES ACROSS THE REGION. MINOR URBAN FLOODING IS POSSIBLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC NEAR TERM...JC/DW SHORT TERM...JC LONG TERM...JC AVIATION...MPS MARINE...MPS HYDROLOGY...JC

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