Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 280625 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 225 AM EDT SAT MAR 28 2015 .SYNOPSIS...
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LOW PRESSURE OFF THE MID ATLANTIC COAST DEEPENS AND TRACKS NORTHEAST THROUGH SATURDAY NIGHT...REACHING THE CANADIAN MARITIME. HIGH PRESSURE BUILDS INTO THE REGION SATURDAY NIGHT INTO SUNDAY...FOLLOWED BY A SERIES OF FRONTAL SYSTEMS THAT WILL IMPACT THE AREA THROUGH THE UPCOMING WEEK.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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LOW PRESSURE WAS DEEPENING EAST OF THE NORTH CAROLINA COAST AT 06Z ALONG A FRONTAL BOUNDARY EXTENDING TO THE NORTHEAST. THE WAVE OF LOW PRESSURE TRACKS NORTHEAST OVERNIGHT. THE PRECIPITATION SHIELD WAS ACROSS EASTERN LONG ISLAND. A BROAD AND FULL AMPLITUDE TROUGH MOVES TOWARD THE COAST OVERNIGHT. A VIGOROUS VORT MAX WAS ROTATING AROUND THE BASE OF THE TROUGH AND WAS MOVING OFF THE GEORGIA AND SOUTH CAROLINA COAST AS SEEN ON THE WATER VAPOR. PRECIPITATION WILL BECOME MORE WIDESPREAD TOWARD MORNING...AND ESPECIALLY ACROSS THE EAST AS THIS VORT MAX MOVES THROUGH THE EASTERN POTION OF THE TROUGH. SO HAVE LIMITED THE WESTWARD EXTENT OF THE POPS OVERNIGHT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
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THE UPPER TROUGH MOVES OVER THE REGION BY 00Z SUNDAY WITH THE INTENSIFYING VORT MOVING SOUTH AND EAST OF THE REGION. THIS DEEPENS THE SURFACE LOW WHICH WILL PASS SOUTH AND EAST OF THE 40N 70W BENCHMARK. AGAIN ENOUGH COLD AIR WILL BE IN PLACE BEHIND THIS LOW FOR THE PRECIPITATION TO BE ALL LIGHT SNOW. WITH THE LOW PASSING WELL TO THE SOUTH AND EAST HAVE CUT BACK OF THE WESTWARD AND NORTHWARD EXTENT OF THE POPS WITH INLAND AREAS RECEIVING LITTLE PRECIPITATION. LIQUID TO SNOW RATIOS AROUND 1 TO 10 AND WITH AROUND A THIRD OF AN INCH MAINLY ACROSS NEW LONDON COUNTY...COULD SEE 2 TO 3 INCHES OF SNOW HERE...AND CLOSE TO WPC SNOW AMOUNTS. WILL HOLD OFF ON AN ADVISORY AT THIS TIME. PRECIPITATION ENDS SLOWLY FROM WEST TO NORTHEAST LATE IN THE DAY AND INTO TONIGHT AS THE SURFACE LOW TRACKS NORTHEAST TOWARD THE CANADIAN MARITIME AND THE UPPER TROUGH AXIS MOVES OFF THE COAST 06Z TO 12Z SUNDAY...WITH HEIGHTS QUICKLY BUILDING. SUNDAY REMAINS DRY WITH UPPER RIDGE AXIS OVER REGION BY 00Z MONDAY...AND THE SURFACE HIGH SLIDING TO THE SOUTH.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A PROGRESSIVE...YET AMPLIFIED FLOW IS BEING ADVERTISED BY THE GLOBAL MODELS THROUGH NEXT WEEK. INITIALLY...A SERIES OF FAST MOVING PAC SYSTEMS RIDE OVER TOP THE RIDGE OVER WESTERN NORTH AMERICA... DROPPING SE ACROSS CENTRAL CANADA AND INTO THE NE QUARTER OF THE NATION. HOWEVER...TOWARD THE END OF THE WEEK...THERE ARE TIMING AND MAGNITUDE DIFFERENCES WITH PAC ENERGY MOVING INTO THE WEST COAST OF THE LOWER 48. THE 12Z ECMWF FOCUSES ON A TRAILING SECOND PIECE OF ENERGY...THUS SLOWING DOWN THE FRONTAL SYSTEM AT THE END OF NEXT WEEK. FOR THE TIME...WILL MAINTAIN A LOW CHANCE OF RAIN SHOWERS THU AND FRI WITH THE POSSIBILITY THAT THIS SYSTEM MAY BE SLOWER THAN CURRENTLY ADVERTISED. THE OTHER SYSTEM THAT MAY BE NOTEWORTHY IS A CLIPPER LOW THAT THE 12Z GFS TAKES JUST NORTH OF NYC AND LI TUE NIGHT...WHILE THE ECMWF IS SIGNIFICANTLY FARTHER SOUTH EMERGING OFF THE MID ATLANTIC COAST. THE LATTER SCENARIO HAS SOME SUPPORT FROM THE GEFS. THIS COULD RAISE CONCERNS FOR SOME WINTRY WEATHER...ESPECIALLY INLAND. FOR NOW...GOING WITH AN ALL RAIN FORECAST BASED ON CLIMO AND MODEL UNCERTAINTY. A MUCH WEAKER COLD FRONT WILL MOVE ACROSS THE AREA MON WITH PERHAPS A FEW SHOWERS. AFTER AN UNSEASONABLY COLD START ON SUN WITH HIGHS 40 TO 45...BOTH HIGHS AND LOWS WILL REBOUND TO NEAR SEASONABLE LEVELS. THE ONE CAVEAT IS A FARTHER SOUTH STORM TRACK TUE NIGHT INTO WED. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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SURFACE LOW PRESSURE DEVELOPING OFF THE MID ATLANTIC COAST WILL PASS WELL TO THE SOUTH AND EAST THROUGH SATURDAY. MEANWHILE...AN UPPER LEVEL DISTURBANCE AND WEAK SURFACE LOW PRESSURE TROUGH WILL MOVE ACROSS THE REGION ON SATURDAY. VFR CONDITIONS AT ALL TERMINALS TO START. EXPECT CIGS TO FALL TO MVFR THEN IFR AT KGON AND MVFR AT KISP AND KBDR IN SNOW. ONSET IS EXPECTED AROUND 09Z AT KGON AND 12Z AT KISP AND KBDR. PRECIPITATIONSHOULD GENERALLY BE SNOW THROUGH THE EVENT...HOWEVER A BRIEF PERIOD IF RAIN IS POSSIBLE AT THE ONSET. RUNWAY ACCUMULATION OF 1-3 INCHES IS FORECAST. THE REST OF THE TERMINALS SHOULD REMAIN VFR THROUGH THE TAF PERIOD...ALTHOUGH A BRIEF PERIOD OF MVFR IS NOT OUT OF THE QUESTION IN ANY LIGHT SNOW THAT DEVELOPS. WINDS INCREASE AS THE PRESSURE GRADIENT TIGHTENS WITH THE OFFSHORE LOW DEEPENING AND GUSTS SHOULD DEVELOP AROUND 12Z OR SO. NYC TERMINALS COULD SEE MORE THAN OCNL GUSTS STARTING AROUND 05Z. .OUTLOOK FOR 06Z SUN THROUGH WED... .SAT NIGHT...CHANCE OF MVFR CONDITIONS WITH ANY SNOW. NW WINDS G20-25KT. .SUNDAY...VFR. .MON...VFR. W WINDS G20KT. .TUE...VFR. .TUE NIGHT...CHANCE OF MVFR CONDITIONS WITH ANY RAIN SHOWERS. .WED...VFR.
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&& .MARINE...
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ROUGH SEAS WILL PERSIST ON THE OCEAN WATERS OVERNIGHT THROUGH SATURDAY MORNING...AND THEN AS LOW PRESSURE PASSES EAST OF CAPE COD ON SATURDAY...THE NW GRADIENT FLOW WILL INCREASE...AND CAN EXPECT SCA GUSTS TO DEVELOP ON THE OCEAN ON SATURDAY...AND THEN ON ALL WATERS BY SATURDAY EVENING. A SMALL CRAFT ADVISORY REMAINS FOR ALL NON OCEAN WATERS SATURDAY EVENING AND LASTING THROUGH SATURDAY NIGHT. A SMALL CRAFT ADVISORY REMAINS ON THE OCEAN FORECAST WATERS THROUGH SATURDAY NIGHT. WAVES DIMINISH TO SUB SCA ON SUNDAY...BUT BUILD TO ABOVE SCA CRITERIA ON A SOUTHERLY FLOW LATE SUNDAY NIGHT INTO MONDAY AHEAD OF AN APPROACHING WARM FRONT. WINDS MAINLY OVER THE OCEAN WATERS WILL GUST TO 25 KT LATE SUNDAY NIGHT INTO MONDAY NIGHT. WINDS AND WAVES WILL DIMINISH ON TUESDAY AS THE PRESSURE GRADIENT RELAXES WITH WEAK HIGH PRESSURE BUILDING IN. THERE IS THE POTENTIAL FOR MARGINAL SCA CONDITIONS TUE NIGHT INTO WED MORNING DEPENDING ON THE TRACK AND INTENSITY OF LOW PRESSURE NEAR THE WATERS. LEANING TOWARD SUB-SCA CONDITIONS AT THIS TIME.
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&& .HYDROLOGY...
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A FEW HUNREDETHS TO A QUARTER INCH LIQUID EQUIVALENT QPF IS POSSIBLE OVERNIGHT THROUGH SATURDAY NIGHT...WITH SOUTHEASTERN CT AND EASTERN LONG ISLAND RECEIVING CLOSE TO 1/3 INCH...AND THE LESS AMOUNTS ACROSS THE LOWER HUDSON VALLEY INTO NORTHEASTERN NEW JERSEY. THE PRECIPITATION FALLS AS SNOW. NO SIGNIFICANT WIDESPREAD PRECIPITATION IS FORECAST SUNDAY INTO NEXT WEEK. RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT INCREASED RIVER/STREAM FLOW ACROSS THE LOWER HUDSON VALLEY AND SOUTHERN CONNECTICUT WILL CONTINUE ICE BREAKUP AND MOVEMENT INTO THIS WEEKEND. ISOLATED ICE JAMS ARE POSSIBLE...WHICH IF THEY OCCUR...COULD RESULT IN LOCALIZED FLOODING. SINCE ICE JAM FLOODING IS UNPREDICTABLE AND SUDDEN...INTERESTS ALONG ICE COVERED RIVERS SHOULD MONITOR NWS FORECASTS FOR THE LATEST INFORMATION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEB SITE.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EDT SUNDAY FOR ANZ338. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT SUNDAY FOR ANZ330-335-340-345. SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ350-353-355.
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&& $$ SYNOPSIS...MPS/DW/MET NEAR TERM...JM/MPS/MET SHORT TERM...MPS LONG TERM...DW AVIATION...BC MARINE...MPS/DW HYDROLOGY...MPS/DW

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