Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 282104 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 404 PM EST SUN DEC 28 2014 .SYNOPSIS...
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A COLD FRONT WILL PASS TO THE SOUTHEAST THIS EVENING. HIGH PRESSURE WILL THEN SLOWLY BUILD IN AND DOMINATE THROUGH FRIDAY...WHILE LOW PRESSURE PASSES WELL TO THE SOUTH ON TUESDAY. ANOTHER LOW PRESSURE SYSTEM SHOULD APPROACH NEXT WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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COLD FRONT NOW THRU MOST OF THE AREA AS OF 20Z EXCEPT FAR ERN LONG ISLAND AND SE CT. A PASSING SHORTWAVE COULD STILL PRODUCE A FEW SPITS OF LIGHT RAIN OVER NYC METRO AND LONG ISLAND THIS EVENING...OTHERWISE SKIES SHOULD CLEAR FROM THE NW...WITH COLDER LOW TEMPS RANGING FROM THE UPPER 30S IN/JUST OUTSIDE NYC...TO THE LOWER/MID 30S ACROSS THE REST OF NYC METRO AND THE COAST...TO THE MID/UPPER 20S INLAND.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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HIGH PRESSURE WILL START TO SLOWLY BUILD FROM THE WEST...WITH MOSTLY CLEAR SKIES AND COLDER TEMPS. A WEAKENING SECONDARY COLD FRONT SHOULD MOVE THROUGH FROM THE NORTH ON MON...SO AFTER MIDDAY HIGHS IN THE LOWER/MID 40S...EXPECT SLOWLY FALLING TEMPS MON AFTERNOON AND THEN MUCH COLDER AIR FOR MON NIGHT. LOW TEMPS AT DAYBREAK TUE SHOULD BE NEAR 30 IN MIDTOWN NYC...IN THE 30S MOST ELSEWHERE...AND IN THE UPPER TEENS IN THE COLDER INTERIOR VALLEYS AND LONG ISLAND PINE BARRENS.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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STARTING OFF ON TUESDAY...MORE OF A CONSENSUS NOW WITH DRY WEATHER PREVAILING. CURRENT AND PREVIOUS RUNS OF CMC...ECMWF...AND GFS KEEP PRECIP WELL SOUTH OF THE REGION IN ASSOCIATION WITH THE WAVES OF LOW PRESSURE RIDING ALONG THE STALLED FRONT. EVEN MAJORITY OF GFS ENSEMBLE MEMBERS KEEP THIS PRECIP SUPPRESSED TO THE SOUTH. OVERALL...QUASI-ZONAL FLOW THROUGH FRIDAY WITH A RIDGING TREND FOR NEXT WEEKEND. THE MAIN UPPER LEVEL JET WILL BE ALIGNED IN A SIMILAR FASHION AND MOVING SLIGHTLY SOUTH OF THE REGION FOR MIDWEEK BEFORE TRENDING BACK NORTH OF THE AREA FOR THE WEEKEND. AT THE SURFACE...VERY STRONG HIGH PRESSURE BUILDS INTO THE NORTHWEST PART OF THE COUNTRY AND THIS SINKS SOUTHEAST THROUGH MIDWEEK. THIS WILL BE A SOURCE FOR VERY COLD AIR AND PERIODIC SHORTWAVES WILL MOVE ACROSS THE LOCAL REGION TO HELP WITH ADVECTING THE COLDER AIR MASS INTO THE REGION. LOW LEVEL ENVIRONMENT WILL ALSO BECOME VERY DRY AS DIAGNOSED BY FORECAST LAYER PRECIPITABLE WATERS AROUND A TENTH OF AN INCH TUESDAY THROUGH THURSDAY. THIS WILL BE ON AN INCREASING TREND TOWARDS THE WEEK BUT AGAIN THERE IS UNCERTAINTY WITH THE FORECAST FOR DAY 7 THROUGH DAY 8 TIME FRAME. THIS IS CONVEYED BY NEARLY A 90 DEGREE PHASE SHIFT BETWEEN CONSECUTIVE RUNS OF THE ECMWF WITH REGARDS TO UPPER LEVEL HEIGHT CONTOUR ORIENTATION. HOWEVER...DID INCREASE POPS A LITTLE WITH AGREEMENT ON PRECIP BETWEEN DGEX...GFS...AS WELL AS SOME GFS ENSEMBLE MEMBERS. JUST A MATTER OF PRECIP TYPE. THIS FORECAST HAS A MIX OF RAIN AND SNOW...SNOW PROBABLY AT ONSET DUE TO WET BULB COOLING AND THEN CHANGING OVER TO RAIN WITH MORE SOUTHERLY FLOW. HOWEVER...THE CONFIDENCE IS VERY LOW FOR DAY 7 AND DAY 8 TIME FRAME...SO SUBSEQUENT FORECASTS COULD VARY WITH TIMING...PLACEMENT...AS WELL AS PRECIP TYPES. CONCERNING TEMPERATURES...TUESDAY THROUGH THURSDAY IS WHEN THE BULK OF THE COLD AIR MASS IS IN PLACE WITH HIGHS HOVERING NEAR TO SLIGHTLY ABOVE FREEZING ON AVERAGE. NEAR NORMAL TEMPERATURES RETURN BY FRIDAY AND POSSIBLY ABOVE NORMAL FOR THE WEEKEND. AGAIN...LOWER CONFIDENCE WITH TEMPERATURES NEXT WEEKEND DUE TO AFOREMENTIONED UNCERTAINTY. DRY WEATHER IN THE LONG TERM UNTIL NEXT WEEKEND WITH THE NEXT APPROACHING LOW PRESSURE SYSTEM.
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&& .AVIATION /21Z SUNDAY THROUGH FRIDAY/...
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A COLD FRONT MOVES EAST OF THE TERMINALS THIS EVENING FOLLOWED BY HIGH PRESSURE BUILDING IN FROM THE WEST TONIGHT. W WINDS AROUND 5 TO 10 KT WILL VEER TO THE NW THIS EVENING AND OVERNIGHT. BRIEF -SHRA POSSIBLE ACROSS CITY AND LONG ISLAND TERMINALS THIS EVENING...BUT CONFIDENCE IS LOW TO INCLUDE IN TAF. OTHERWISE...VFR EXPECTED THROUGH TONIGHT. FLOW REMAINS NW MONDAY MORNING 8 TO 10 KT. .OUTLOOK FOR 18Z MON THROUGH FRI... .MON-WED...VFR. .THU...VFR. SW WIND GUSTS TO 25 KT POSSIBLE. .FRI...VFR.
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&& .MARINE...
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COLD FRONT SHOULD MAINTAIN A MODERATE NW FLOW TONIGHT OUT EAST... WITH WIND GUSTS CLOSE TO 25 KT AND 5-FT SEAS ON THE OCEAN E OF MORICHES INLET AT LEAST INTO THIS EVENING IF NOT ALL NIGHT. EXTENDED SCA OUT EAST THROUGH TONIGHT. SCA CONDS ARE AGAIN POSSIBLE LATE TUE NIGHT THROUGH WED...WITH A BETTER CHANCE WED NIGHT THROUGH FRI...WHEN OCEAN SEAS ARE FORECAST TO REACH 5-7 FT MAINLY EAST OF FIRE ISLAND INLET. THIS WILL BE COINCIDING WITH COLDER AIR MOVING IN AND BETTER MIXING OVER THE RELATIVELY WARMER WATERS.
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&& .HYDROLOGY...
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NO SIGNIFICANT PRECIPITATION OF 1/2 INCH OR MORE EXPECTED THROUGH FRI. WIDESPREAD PRECIP POSSIBLE FOR NEXT WEEKEND...BUT IT IS TOO EARLY TO TELL IF IT WILL BE SIGNIFICANT.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ350.
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&& $$ SYNOPSIS...GOODMAN/JM NEAR TERM...GOODMAN SHORT TERM...GOODMAN LONG TERM...JM AVIATION...DS MARINE...GOODMAN/JM HYDROLOGY...GOODMAN/JM

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