Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 220910 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 410 AM EST THU JAN 22 2015 .SYNOPSIS...
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HIGH PRESSURE BUILDS IN TODAY THROUGH FRIDAY AFTER A WEAK TROUGH OF LOW PRESSURE SHIFTS OUT OF THE REGION THIS MORNING. IT THEN MOVES OFF THE MID ATLANTIC COAST FRIDAY NIGHT AS A RAPIDLY DEEPENING LOW EMERGES FROM THE GULF COAST STATES. THE LOW WILL TRACK TO THE MID ATLANTIC COAST SATURDAY MORNING...PASSING SOUTH AND EAST OF SOUTHERN NEW ENGLAND SATURDAY NIGHT. HIGH PRESSURE BRIEFLY FOLLOWS FOR SUNDAY BEFORE ANOTHER LOW PRESSURE SYSTEM POSSIBLY IMPACTS THE REGION MONDAY INTO MONDAY NIGHT. HIGH PRESSURE WILL RETURN FOR THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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THERE COULD BE A LINGERING SNOW SHOWER THIS MORNING MAINLY OVER EASTERN LI AND SE CT AS AN UPPER TROUGH AXIS/SHORTWAVE SHIFTS THROUGH WHILE A DISSIPATING SURFACE TROUGH REMAINS IN THE VICINITY. DRY WEATHER IS THEN EXPECTED FOR THE AFTERNOON AS THE FLOW ALOFT BECOME MORE ANTICYCLONIC AND HIGH PRESSURE BUILDS IN AT THE SURFACE. A NEARLY EVEN BLEND OF MAV AND NAM MOS WAS USED FOR HIGH TEMPERATURES...WHICH ARE EXPECTED TO REACH NEAR NORMALS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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RIDGING AT THE SURFACE AND ALOFT CONTINUES TONIGHT AND FRIDAY. THIS KEEPS US DRY THROUGH THE PERIOD. OVERNIGHT LOWS SHOULD BE CLOSE TO NORMALS. ALTHOUGH TEMPS ALOFT RISE ON FRIDAY...SUBSIDENCE ASSOCIATED WITH THIS DEEP-LAYERED RIDGING WILL LIMIT THE MIXING DEPTH. HIGHS LOOK TO BE CLOSE TO NORMAL LEVELS ONCE AGAIN...PERHAPS A DEGREE OR TWO COOLER THAN TODAY FOR MOST SPOTS.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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ALL ATTENTION IS FOCUSED ON A RAPIDLY DEEPENING LOW THAT EMERGES FROM EASTERN GULF OF MEXICO FRI NIGHT AND RAPIDLY TRACKS UP THE EASTERN SEABOARD SAT...PASSING NEAR THE 40N...70W BENCHMARK. THE MODELS AT THIS POINT IN TIME ARE IN RELATIVELY DECENT AGREEMENT WITH THE RAPID INTENSIFICATION AND TRACK...WITH SUBTLE DIFFERENCES IN TIMING AND TRACK. OF THE OPERATIONAL MEMBERS...THE 00Z ECMWF IS THE WETTER AND FARTHEST WEST IN TRACK..BUT NOT BY A WHOLE LOT. THE REAL TROUBLING PART OF THE FORECAST IS PTYPE...ESPECIALLY ALONG THE COAST WHERE THE GREATEST AMOUNTS OF QPF ARE FORECAST. THERE IS NO HIGH IN PLACE TO THE NORTH WHICH IS OFTEN THE MOST CRITICAL ELEMENT TO MAINTAIN A COLD AIR SUPPLY FOR A NOR`EASTER. THAT BEING THE CASE...STRONG DYNAMICAL FORCING WITH A COUPLING JET STRUCTURE BETWEEN THE NORTHERN AND SOUTHERN BRANCHES AND A STRONG NLY FLOW DUE TO THE ISALLOBARIC WIND WILL PROVIDE AN AIRMASS SUPPORTIVE OF PRIMARILY SNOW...OR A WINTRY MIX OF RAIN...SNOW...AND FREEZING RAIN. THIS MAKES FOR A CHALLENGING FORECAST WITH RESPECT TO STORM TOTALS. TO THE NORTH AND WEST OF THE COAST...THE EVENT WILL BE PRIMARILY SNOW...BUT LESS QPF. SO FOR DIFFERENT REASONS...MUCH OF THE TRI-STATE AREA SHOULD SEE A STRONG ADVISORY LEVEL EVENT WITH 2 TO 5 INCHES OF SNOW AND SOME ICE ACCRETION UP TO A TENTH OF AN INCH. SHOULD THE EVENT STAY ALL SNOW...THEN EASTERN AREAS COULD SEE A WARNING LEVEL EVENT. THERE CONTINUES TO BE NO SIGNS OF PHASING BETWEEN THE TWO STREAMS OF THE POLAR JET. THIS WILL NEED TO BE WATCHED AS THIS COULD DRAW THE DEEPENING LOW FARTHER WEST. RIGHT NOW THOUGH...A RAPIDLY DEEPENING LOW PASSING NEAR THE BENCHMARK IS WHAT THE LATEST GUIDANCE CONTINUES TO HONE IN ON. TEMPS ON SAT WILL STRUGGLE TO GET MUCH ABOVE FREEZING WITH THE LOW-LEVEL COLD AIR BEING MAINTAINED BY THE NLY FLOW. THERE ARE NO PLANNED HAZARD PRODUCTS AT THIS TIME. THE HWO WILL BE UPDATED. WEAK SFC HIGH PRES WILL BUILD OVER THE AREA ON SUNDAY BEHIND THE DEPARTING LOW. DEEP UPPER TROUGH THEN BUILDS EAST AND WILL ENCOMPASS MUCH OF THE EASTERN THIRD OF THE U.S. FOR THE START OF THE NEW WEEK. THERE IS THE POTENTIAL FOR ANOTHER STRONG COASTAL LOW ALONG THE MID ATLANTIC COAST MON AS A STRONG CLIPPER LOW APPROACHES THE REGION. MODELS HAVE BOUNCED BACK AND FORTH WITH A CLOSED LOW FORMING ALONG THE MID ATLANTIC COAST WITH MDT-HVY SNOW TO THE NORTH OF THE LOW CENTER. 00Z GFS IS THE MOST AGGRESSIVE WITH THIS SYSTEM WITH A SIGNIFICANT SNOWFALL FOR THE REGION...WHILE THE ECMWF AND GGEM ARE PROGRESSIVE. DRY CONDS RETURN FOR THE MIDDLE TO END OF NEXT WEEK.
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&& .AVIATION /09Z THURSDAY THROUGH MONDAY/...
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LOW PRESSURE TROUGH EXITS THIS MORNING TO THE EAST OF THE TERMINALS WITH ANOTHER LOW DEEPENING FAR OFF THE EASTERN SEABOARD. ANY RESIDING MVFR SHOULD IMPROVE TO VFR BY LATER THIS MORNING AND CONTINUE THROUGH THE REST OF THE TAF PERIOD WITH HIGH PRESSURE BUILDING IN FROM THE WEST. THERE IS A CHANCE OF MVFR 12-18Z...MORE SO FOR EASTERN TERMINALS. ANY SNOW WILL BE WIDELY SCATTERED IN COVERAGE FOR THIS MORNING. N WINDS AROUND 5 KT BACK TO NW TODAY INCREASING TO 5-10 KT. THIS NW FLOW CONTINUES INTO TONIGHT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. WINDS COULD END UP BEING JUST LEFT AROUND 10 DEGREES LEFT OF 310 FOR THIS AFTERNOON. KLGA FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. KEWR FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. WINDS COULD END UP BEING JUST LEFT AROUND 10 DEGREES LEFT OF 310 FOR THIS AFTERNOON. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. KHPN FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. KISP FCSTER COMMENTS: UNCERTAIN ON MVFR WHICH COULD LAST AN EXTRA 1-2 HRS COMPARED TO FORECAST. .OUTLOOK FOR 09Z FRIDAY THROUGH MONDAY... .FRIDAY...VFR. .FRIDAY NIGHT-SATURDAY...MVFR/IFR WITH SNOW DEVELOPING LATE. PRECIP BECOMES MORE OF A MIX OF RAIN OR FREEZING RAIN LATER IN AFTERNOON. N-ENE WINDS G15-25KT. .SATURDAY NIGHT...PRECIP TAPERS OFF WITH GRADUAL IMPROVEMENT. .SUNDAY...VFR-MVFR WITH STRONG NW WINDS IN THE WAKE OF DEPARTING LOW PRESSURE. .LATE SUNDAY-MONDAY...ANOTHER STORM SYSTEM POSSIBLE. MVFR-IFR IN SNOW IF STORM OCCURS.
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&& .MARINE...
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TRANQUIL CONDITIONS ON THE WATERS TODAY WITH A LIGHT NW FLOW. WINDS PICK UP TONIGHT AS THE PRESSURE GRADIENT INCREASES OVER THE WATERS. WINDS AT THE TOP OF THE MIXED LAYER AREN`T MUCH STRONGER THAN THE SURFACE WINDS...SO NOT EXPECTING TO SEE ADVISORY-LEVEL GUSTS AS HIGH PRESSURE BUILDS IN BEHIND A LOW PRESSURE SYSTEM STRENGTHENING WELL OUT TO SEA. A WEST FLOW AROUND 10 KT ON FRIDAY WILL THEN MAINTAIN SUB-ADVISORY CONDITIONS ACROSS ALL WATERS. LOW PRES MOVES ALONG THE ATLANTIC COAST ON SATURDAY AND PASSES EAST OF CAPE COD SATURDAY NIGHT. SCA CONDS LIKELY ON ALL WATERS SATURDAY NIGHT THROUGH SUNDAY MORNING WITH THE POTENTIAL FOR GALES ON THE EASTERN OCEAN WATERS AND POSSIBLY EASTERN LI SOUND SATURDAY NIGHT. ROUGH OCEAN SEAS LIKELY AT THAT TIME.
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&& .HYDROLOGY...
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LOW PRESSURE IMPACTS THE REGION SATURDAY AND SATURDAY NIGHT WITH QPF UP TO 1 INCH ACROSS FAR EASTERN LI/SE CT...AND ABOUT HALF AN INCH OR LESS FROM NYC AND POINTS NORTH AND WEST. THIS WILL POTENTIALLY FALL AS A MIX OF SNOW...RAIN...AND FREEZING RAIN. QPF OF 1/4 TO 1/2 INCH LIQUID EQUIVALENT ALSO POSSIBLE MONDAY THROUGH TUESDAY AS A COASTAL LOW PASSES SOUTH OF THE REGION. THIS EVENT LOOKS TO BE PRIMARILY SNOW AT THIS TIME. ICE ON THE WALLKILL AND YANTIC RIVERS IS CAUSING MINOR FLUCTUATIONS IN RIVER LEVELS AT THIS TIME.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC/DW NEAR TERM...JC SHORT TERM...JC LONG TERM...DW AVIATION...JM MARINE...JC/DW HYDROLOGY...JC/DW

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