Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 210247 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 947 PM EST SAT DEC 20 2014 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE WILL CROSS THE AREA LATE TONIGHT INTO SUNDAY MORNING...OTHERWISE HIGH PRESSURE REMAINS NEARLY STATIONARY TO THE NORTH ACROSS THE SAINT LAWRENCE RIVER VALLEY FOR THE REMAINDER OF THE WEEKEND. A WARM FRONT APPROACHES MONDAY AFTERNOON...AND REMAINS SOUTH OF THE AREA TUESDAY AND TUESDAY NIGHT. A STORM SYSTEM WILL IMPACT THE AREA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...ENDING EARLY CHRISTMAS MORNING. HIGH PRESSURE BUILDS IN LATE THURSDAY INTO FRIDAY. ANOTHER LOW WILL AFFECT THE REGION NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... FLURRIES CONTINUE TO BE REPORTED OVER MAINLY EASTERN SECTIONS OF THE CWA. 00Z SOUNDING ONLY SHOWS SATURATION TO ABOUT -10C. HOWEVER...PROXIMITY TO THE OCEAN AND THEREFORE SEA SALT MAY ACT AS ICE NUCLEI...WHICH CAN FORM ICE CRYSTALS AT WARMER TEMPS. THE ONLY AREA THAT MIGHT SEE SOME RAIN MIX IN IS THE TWIN FORKS OF LONG ISLAND AND PERHAPS PORTIONS OF NEW LONDON IN CT. MESOSCALE MODELS SHOW THAT THE PRECIP SHOULD CONTINUE OVERNIGHT...THOUGH THE TEMPERATURE/DEWPOINT SPREAD SHOULD ONLY AMOUNT TO FLURRIES. HOWEVER...CANNOT RULE OUT A DUSTING OR COATING IN SOME SPOTS...ESPECIALLY HIGHER ELEVATIONS OF CT. OTHERWISE...FORECAST IS ON TRACK WITH ONLY MINOR CHANGES MADE TO REFLECT CURRENT OBS. CLOUD COVER AND A NLY FLOW TODAY KEPT TEMPS IN CHECK WITH AFTERNOON HIGHS ONLY IN THE UPPER 20S TO THE LOWER 30S. THE LAST DAY OF AUTUMN WILL FINISH AS ONE OF THE COLDEST. WINTER SOLSTICE IS 603 PM SUNDAY EVENING. COLD HIGH PRESSURE SETTLES OVER THE SAINT LAWRENCE RIVER VALLEY THIS EVENING. THIS WILL MAINTAIN THE COLD AIR SUPPLY WITH LIGHT NLY WINDS. LOW-LEVEL MOISTURE WILL ALSO REMAIN TRAPPED BENEATH A STRONG INVERSION AT APPROXIMATELY 900 MB. THUS...LOOKING AT CONTINUED CLOUDY SKIES TONIGHT. THIS WILL KEEP TEMPS FROM DROPPING TOO FAST WITH LOWS RANGING FROM THE LOWER 20S WELL INLAND TO AROUND 30 AT THE COAST. A SHORT WAVE TROF OVER THE OHIO VALLEY THIS EVENING WILL MOVE ACROSS THE AREA LATE TONIGHT. THIS COUPLED WITH THE LOW-LEVEL MOISTURE MAY PROVIDE JUST ENOUGH LIFT FOR SNOW FLURRIES OR VERY LIGHT SNOW...WITH THE BEST CHANCE BEING ACROSS EASTERN LI AND SE CT. LITTLE OR NO SNOW ACCUMULATION IS FORECAST. THERE COULD ALSO BE SOME RAIN MIXED IN AND/OR FREEZING RAIN WITH LACK A ICE CRYSTALS IN THE CLOUD BEARING LAYER. OFTEN THOUGH ALONG THE COAST...SEA SALT CAN LOWER THE ACTIVATION TEMP OF ICE NUCLEI. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... MORNING FLURRIES AND/OR SPRINKLES WILL GIVE WAY TO PARTIAL CLEARING BY AFT AS SHORT WAVE RIDGING BUILDS IN ALOFT. FAR EASTERN LI AND SE CT COULD STAY MOSTLY CLOUDY ALL DAY DUE TO DEEPER MOISTURE IN PLACE BENEATH AN INVERSION. HIGHS ON SUN WILL APPROACH 40 ALONG THE COAST,,,BUT A FEW DEGREES COOLER INLAND. THIS COULD VARY BASED ON THE EXTENT OF CLEARING. HIGH PRESSURE BUILDS SLOWLY SOUTH AND EAST INTO THE CANADIAN MARITIMES...WITH LOW-LEVEL NLY WINDS GRADUALLY VEERING SUN NIGHT. LOWS WILL ONCE AGAIN BE IN THE 20S SUN NIGHT...BUT THE EXTENT OF THE CLOUD COVER REMAINS SOMEWHAT UNCERTAIN AS THE FLOW BECOMES MORE NE. && .LONG TERM /MONDAY THROUGH SATURDAY/... A WEAK WAVE OF LOW PRESSURE DEVELOPS ALONG THE SOUTHEAST COAST MONDAY...AND WILL BE ON A DEVELOPING WARM FRONTAL BOUNDARY. THIS LOW REMAINS WEAK AS THE WARM FRONT MOVES SLOWLY NORTH MONDAY NIGHT INTO TUESDAY. MEANWHILE HIGH PRESSURE OVER NEW ENGLAND INTO SOUTHEASTERN CANADA WEAKENS. AT THE UPPER LEVELS A FULL LATITUDE TROUGH DEVELOPS MONDAY FRONT CENTRAL CANADA INTO MEXICO WITH SURFACE LOW PRESSURE DEEPENING IN THE UPPER MIDWEST. DURING WEDNESDAY THE TROUGH BECOMES NEGATIVE WITH THE LOW MOVING THROUGH THE WESTERN GREAT LAKES. THE WARM FRONT IS EXPECTED TO REMAIN SOUTH OF THE REGION TUESDAY INTO WEDNESDAY. SO WITH WEAK LIFT DEVELOPING AHEAD OF THE WARM FRONT WILL KEEP CHANCE POPS MONDAY AFTERNOON INTO TUESDAY. GUIDANCE IS NO LONGER DEEPENING WITH COASTAL LOW AND KEEP THE LOW OVER THE GREAT LAKES AS THE PRIMARY LOW WITH THE NEGATIVE TROUGH. AS THE LOWS COLD FRONT APPROACHES LATE TUESDAY NIGHT INTO WEDNESDAY...A STRONG LOW LEVEL JET TO NEAR 70 KT DEVELOPS. WITH A DEEP SOUTHERLY FLOW LIMITING MIXING STRONG GUSTY WIND WILL BE LIMITED. HOWEVER THE LOW LEVEL JET WILL PROVIDE STRONG LIFT DURING WEDNESDAY AND PERIODS OF MODERATE TO HEAVY RAINFALL IS EXPECTED. WARMING OCCURS TUESDAY INTO WEDNESDAY WITH ALL LIQUID DURING THIS TIMEFRAME. BEFORE THAT...MONDAY NIGHT...SOME LIGHT SNOW AND RAIN WILL BE POSSIBLE INLAND...HOWEVER NO ACCUMULATIONS ARE EXPECTED. THE THERMAL PROFILE OF THE GFS WAS SLIGHTLY WARMER THAN THE 20/00Z ECMWF AND USED A BLEND FOR P-TYPE. AS THE PARENT LOW MOVES INTO SOUTHEASTERN CANADA LATE WEDNESDAY INTO WEDNESDAY NIGHT A COLD FRONT WILL CROSS THE REGION AFTER 05Z INTO EARLY THURSDAY MORNING...PASSING JUST EAST OF THE AREA AROUND 12Z THURSDAY. WITH TIMING CONSISTENCY HAVE KEPT THE LIKELY AND CATEGORICAL POPS FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. IN THE COLDER AIR BEHIND THE FRONT THURSDAY AND WITH CYCLONIC WEST TO NORTHWEST FLOW...STRONG AND GUSTY WIND WILL BE LIKELY. HAVE KEPT BELOW ADVISORY CRITERIA FOR NOW...HOWEVER GUSTS COULD BE CLOSE TO 45 KT AT TIMES THURSDAY. HIGH PRESSURE BUILDS IN FOR FRIDAY WITH LIGHTER WINDS. THEN FOR NEXT WEEKEND ANOTHER INLAND LOW PRESSURE SYSTEM WILL IMPACT THE AREA. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE BUILDS OVER THE AREA FOR THE REMAINDER OF THE WEEKEND AND DEPARTS EARLY IN THE WEEK. MAINLY MVFR CIGS BETWEEN 2-3 KFT. NYC METRO TERMINALS ARE BEGINNING TO DROP TO MVFR AND THINK THEY WILL REMAIN BETWEEN 2-3KFT THROUGH THE OVERNIGHT AS A SHORTWAVE TROUGH APPROACHES AND MOVES ACROSS. LIGHT SNOW AND/OR FLURRIES POSSIBLE FOR KGON/KISP/KBDR TONIGHT...BUT NOT EXPECTED TO IMPACT VSBY AND CHC`S AREN`T HIGH ENOUGH TO INCLUDE IN TAFS. MAY BE TOO OPTIMISTIC WITH CIGS IN NYC METRO AT 12Z AND MVFR COULD LINGER INTO THE AFTN. LIGHT AND VRB WINDS OVERNIGHT...THEN COULD BACK 20-30 DEGREES MORE TO THE LEFT OF 00Z FORECAST DURING THE DAY SUN. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .SUN NIGHT...VFR. .MON-MON NIGHT...MVFR OR LOWER POSSIBLE IN E FLOW. CHC OF RAIN. .TUE-TUE NIGHT...IFR LIKELY IN RAIN...CIGS AND VSBYS. E WINDS 10-20 KT...BECOMING SE. .WED...HIGH IMPACT EVENT POSSIBLE...IFR LIKELY WITH HEAVY RAIN AND GUSTY SE WINDS 25KT+ SHIFTING TO SW LATE WED. .THU...SUB VFR EARLY IN SHOWERS...THEN VFR WITH GUSTY WESTERLY WINDS 20-25 KT G40 KT. && .MARINE... FORECAST ON TRACK...NO CHANGES AT THIS TIME. WITH HIGH PRES BUILDING NORTH OF 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. A LIGHT EAST TO SOUTHEAST FLOW MONDAY INTO TUESDAY AHEAD OF A WARM FRONT WILL REMAIN BELOW SMALL CRAFT LEVELS...WITH SEAS ALSO REMAINING BELOW 5 FT. DEEPENING LOW PRESSURE MOVING THROUGH THE WESTERN GREAT LAKES WEDNESDAY WITH A COLD FRONT APPROACHING THE AREA WATERS WILL RESULT IN AN INCREASING SOUTHERLY FLOW. SMALL CRAFT WIND AND SEAS WILL BE POSSIBLE ON THE OCEAN LATE TUESDAY INTO TUESDAY NIGHT...AND ACROSS ALL THE WATERS WEDNESDAY. THEN IN THE COLDER AIR BEHIND THE COLD FRONT THURSDAY WIND GUSTS WILL BE GALE FORCE ACROSS ALL THE WATERS AND REMAIN INTO THURSDAY NIGHT WITH GUSTS DIMINISHING TOWARD FRIDAY MORNING...WITH GUSTS BELOW SMALL CRAFT LATER WEDNESDAY MORNING. SEAS ON THE OCEAN WATERS WILL REMAIN AT SMALL CRAFT LEVELS THROUGH FRIDAY. && .HYDROLOGY... RAINFALL FROM MONDAY AFTERNOON THROUGH WEDNESDAY NIGHT COULD TOTAL 1 TO 2 INCHES WITH LOCALLY HIGHER AMOUNTS. MUCH OF THE RAINFALL IS EXPECTED TO OCCUR WEDNESDAY INTO WEDNESDAY NIGHT. MINOR URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...MET/DW NEAR TERM...MET/DW SHORT TERM...DW LONG TERM...MET AVIATION... MARINE...MET/DW HYDROLOGY...MET/DW

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