Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211759 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1259 PM EST SUN DEC 21 2014 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE WILL CROSS THE AREA TODAY WITH A SURFACE TROUGH REMAINING NEARBY. HIGH PRESSURE OTHERWISE REMAINS OVER THE REGION 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 BREEZY CONDITIONS IN ITS WAKE ON CHRISTMAS. HIGH PRESSURE BUILDS IN ON FRIDAY. ANOTHER LOW WILL THEN AFFECT THE REGION NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRESSURE PROVIDES FOR DRY WEATHER FOR MOST OF THE CWA. HOWEVER...A SURFACE TROUGH OVER EASTERN ZONES WILL ACT AS A FOCUS FOR MOISTURE CONVERGENCE...AND LIFT WILL BE PROVIDED ALOFT AS A SHORTWAVE PASSES THROUGH. PCPN TYPE MAINLY SNOW WITH SUFFICIENT ICE NUCLEI LIKELY PRESENT...BUT BOUNDARY LAYER TEMPS ACROSS EASTERN LONG ISLAND COMPLICATE THE FORECAST. PROBABLY A MIXTURE OF LIGHT RAIN AND SNOW THERE...PROBABLY EVEN MOSTLY OR ALL RAIN OVER THE PARTS OF THE FORKS REGION. IN SHORT...TRACE TO HALF INCH OF SNOW CURRENTLY FORECAST OVER LONG ISLAND...WITH UP TO AROUND AN INCH ACROSS PARTS OF SE CT. MOST OF THE REST OF THE CWA COULD GET A FLURRY OR TWO THIS MORNING. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... LIFT AND MID LEVEL MOISTURE EXIT EAST BY EARLY THIS EVENING...AND THE SURFACE TROUGH IS PROGGED TO WEAKEN AS IT SHIFTS SLIGHTLY WEST. WILL GO WITH SCT FLURRIES OVER LI AND CT...AND PCPN TYPE OF SPRINKLES ALSO PROBABLY PRESENT EARLY IN THE EVENING FOR THE COASTAL SECTIONS. 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 ALLOW 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 RESERVED FOR THE AFTERNOON. THE LOW CENTER WEAKENS AS IT HEADS NORTH MONDAY NIGHT. 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. CHC POPS FOR THIS PERIOD. THERMAL PROFILES SUPPORT RAIN FOR MOST OF THE CWA. HOWEVER...FOR SOME NW SECTIONS...MODELS SHOWING A WARM NOSE ALOFT...ALLOWING FOR A CHANCE OF SLEET DURING THE EVENING...THEN POSSIBLY FREEZING RAIN AS THE WARMEST PART OF THE NOSE EXCEEDS 3C AND SURFACE TEMPS HOVER AROUND FREEZING. && .LONG TERM /TUESDAY THROUGH SATURDAY/... WEAK LOW TO THE SOUTH CONTINUES TO WEAKEN ON TUESDAY...BUT THE SURFACE TROUGH REMAINS IN THE VICINITY. ECMWF OVER THE PAST FEW RUNS HAS BEEN CONSISTENTLY WETTER FOR TUESDAY...WITH THE GFS CONSISTENTLY DRIER...AND THE NAM SOMEWHERE IN BETWEEN DEPENDING ON LOCATION. WILL CAP POPS AT 50% AS PER PREVIOUS FORECAST GIVEN THE UNCERTAINTY. FREEZING RAIN STILL POSSIBLE EARLY ON IN THE MORNING FOR THE FAR NW PORTION OF THE CWA...OTHERWISE...LIGHT RAIN. RAIN THEN BECOMES MORE LIKELY TUESDAY NIGHT. 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 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. MODELS HAVE TRENDED SLOWER WITH THE PASSAGE OF THE FRONT...SO BY CHRISTMAS MORNING...SHOWERS STILL LIKELY EARLY ON FOR THE EASTERN FRINGE OF THE CWA...WITH MAINLY LOW CHANCES OF SHOWERS ELSEWHERE. BY NOON...LIKELY DRY EVERYWHERE. 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. LOOKS LIKE WE FALL SHORT OF WIND ADVISORY CRITERIA HOWEVER. WILL NEED TO KEEP AND EYE ON THIS TO SEE IF THE WEAKENING TREND CONTINUES. TEMPS DURING THIS PERIOD WILL BE ABOVE AVERAGE. HIGHS ON WEDS IN WELL INTO THE 50S...AND WITH A MODERATE WSW FLOW AND PARTIAL SUNSHINE ON THURSDAY...HIGH TEMPS IN THE UPPER 40S TO LOWER 50S EXPECTED. HIGH PRESSURE BUILDS IN FOR FRIDAY WITH LIGHTER WINDS COOLER TEMPS...BUT STILL ABOVE NORMALS. THEN FOR NEXT WEEKEND...ANOTHER INLAND LOW PRESSURE SYSTEM COULD IMPACT THE AREA. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... BASED ON RECENT TRENDS...WILL MAINTAIN MVFR CIGS FOR THE REMAINDER OF THE AFTERNOON THROUGH MON. LATEST SAT IMAGERY SHOWS NO SIGNS OF IMPROVEMENT WITH WEAK SFC TROF DRAPED ACROSS AREA AND MOISTURE TRAPPED BENEATH A WEAKENING LOW-LEVEL INVERSION. CIGS MAY EVEN DROP TO IFR LATE TONIGHT INTO MON...BUT CONFIDENCE IS LOW. POCKETS OF LIGHT RAIN/DRIZZLE/SNOW WILL POSSIBLE THROUGH THE AFTERNOON WITH THE AFOREMENTIONED TROF IN PLACE...MAINLY EAST OF THE NYC TERMINALS. A WEAK NLY FLOW AT LESS THAN 10 KT GRADUALLY VEERS AROUND TO E/NE BY MON AFT. .OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY... .MONDAY AFTERNOON-MONDAY NIGHT...MVFR OR LOWER POSSIBLE IN E FLOW. RAIN DEVELOPING IN THE AFTERNOON AND AT NIGHT. .TUESDAY-TUESDAY NIGHT...IFR CIGS/VSBYS LIKELY IN RAIN. E WINDS 10-20 KT...BECOMING SE. .WEDNESDAY...HIGH IMPACT EVENT BECOMING LIKELY. IFR CONDS WITH HEAVY RAIN AND S/SE WINDS 15-20 KT WITH 20-25 KT GUSTS. WINDS SHIFT TO THE SW LATE WEDNESDAY NIGHT. .THURSDAY...SUB-VFR CONDS IN THE MORNING IN RAIN SHOWERS. VFR CONDS BY AFTERNOON. WEST WINDS 15-20 KT WITH 25-35 KT GUSTS. .FRIDAY...VFR. && .MARINE... HIGH PRES BUILDS NORTH OF THE WATERS. NORTH WINDS 10 KT OR LESS ALONG WITH SEAS GENERALLY 1-2 FT ON THE OCEAN OR 1 FT OR LESS ON ALL OTHER WATERS TODAY AND TONIGHT. 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. && $$

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