Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270529 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1229 AM EST FRI FEB 27 2015 .SYNOPSIS... HIGH PRESSURE BUILDS FROM THE WEST THROUGH FRIDAY. THIS LARGE AREA OF HIGH PRESSURE WILL PREVAIL ACROSS THE OHIO VALLEY AND MID ATLANTIC STATES THIS WEEKEND BEFORE MOVING OFFSHORE LATE SUNDAY. A FRONTAL SYSTEM WILL THEN MOVE ACROSS THE AREA SUNDAY NIGHT INTO MONDAY. HIGH PRESSURE WILL BRIEFLY RETURN ON TUESDAY BEFORE YET ANOTHER FRONTAL SYSTEM IMPACTS THE AREA FOR THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... THREAT OF FLURRIES OVERNIGHT SHOULD BE RELEGATED WELL N AND W OF NYC WITH APPROACHING BUT SHEARING SHORTWAVE AXIS. HIGH PRESSURE GRADUALLY TOWARDS THE REGION TONIGHT. AHEAD OF IT...WILL HANG ON TO PARTLY TO MOSTLY CLOUDY CONDITIONS THROUGH THE NIGHT. MODELS SIGNALING AREA OF SNOW SHOWERS OVER CENTRAL PA WILL GRADUALLY SLIDE EAST AND WEAKEN OVERNIGHT AS SHEARING SHORTWAVE ENERGY APPROACHES. A FEW SNOW SHOWERS COULD MAKE IT INTO AREAS WEST OF THE HUDSON RIVER TOWARDS DAYBREAK. HAVE LOWERED POPS SLIGHTLY BASED ON DRYING TREND IN 18Z HIGH-RES AND OPER GUIDANCE...AND THIS MAY HAVE TO LOWERED FURTHER OR REMOVED BASED ON RADAR OBS AND 00Z GUIDANCE. TEMPS WILL BE A BIT TRICKY ACROSS OUTLYING AREAS WITH BRIEF WINDOWS FOR RADIATIONAL COOLING OVERNIGHT. OVERALL...A BLEND OF MAV/NAM MOS LOOKED GOOD FOR LOWS...WHICH WILL AVERAGE 10 TO 15 DEGREES BELOW NORMAL. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... HIGH PRESSURE CONTINUES TO BUILD IN AT THE SURFACE THROUGH THE PERIOD. HOWEVER...A SHORTWAVE ALOFT WORKING WITH SUFFICIENT LOW- MID MOISTURE COULD CAUSE FLURRIES AND ISOLATED SNOW SHOWERS DURING THE DAY WITH BETTER OVERALL CHANCES OVER THE WESTERN ZONES. TEMPS AT THE TOP OF THE BOUNDARY LAYER DON`T CHANGE ALL THAT MUCH...SO HIGHS PROBABLY SIMILAR TO TODAY`S...GENERALLY IN THE MID AND UPPER 20S. MOISTURE IN THE LOW-MID LEVELS THEN DIMINISHES FRIDAY NIGHT...SO TURNING CLEAR AND REMAINING COLD AS WINDS WILL BE LIGHT. LOWS 10-15 IN THE CITY WITH SINGLE DIGITS IN MOST SUBURBS. SOME NORTHERN SUBURBS COULD SEE BELOW ZERO LOWS ONCE AGAIN. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... UPPER AIR PATTERN FINALLY SHOWING A CHANGE IN THE UPCOMING WEEK WITH THE HIGH AMPLITUDE RIDGE ACROSS WESTERN NORTH AMERICA BREAKING DOWN WITH A SPLIT CONFLUENT FLOW ACROSS THE MID SECTION OF THE COUNTRY AT THE ONSET OF THE PERIOD. THIS WILL RESULT IN A LARGE AREA OF HIGH PRESSURE BUILDING EAST ACROSS THE OHIO VALLEY AND MID ATLANTIC STATES SAT INTO SUN. A NORTHERN BRANCH AMPLIFYING SHORT WAVE TROF THEN SENDS A FAST MOVING FRONTAL SYSTEM THROUGH THE AREA SUN NIGHT INTO MON...FOLLOWED BRIEFLY BY HIGH PRESSURE TUE...AND THEN ANOTHER SLOWER MID WEEK FRONTAL SYSTEM. THE LATTER OF WHICH DIFFERS SIGNIFICANTLY WITH TIMING WITH THE 12Z ECMWF AND GGEM MUCH SLOWER THAN THE GFS. THIS PATTERN WILL RESULT IN A WARMUP...ALBEIT STILL BELOW NORMAL MOST OF THE PERIOD. SAT WILL BE THE COLDEST DAY WITH HIGHS STILL ON THE ORDER OF 15 TO 20 DEGREES BELOW NORMAL. MODELS POINT TOWARD THE UPPER AIR PATTERN REESTABLISHING A RIDGE ACROSS THE WEST COAST AND A DEEPENING TROF ACROSS THE EAST LATE NEXT WEEK WHICH COULD MEAN ANOTHER SHOT OF COLD AIR. AS FOR THE AFOREMENTIONED FRONTAL SYSTEMS...THE FIRST SUN NIGHT INTO MON MORNING LOOKS TO BE PRIMARILY SNOW AT THIS TIME WITH THE POTENTIAL FOR A FEW INCHES. PREFERENCE WAS TOWARD THE COLDER GFS AND GGEM. THE MID WEEK SYSTEM LOOKS TO START AS SNOW TUE AFT/EVE... THEN TRANSITION OVER TO RAIN TUE NIGHT INTO WED MORNING. THE TRAILING COLD FRONT WILL BE SLOW TO MOVE EAST WED WITH THE POTENTIAL FOR FRONTAL WAVES TO IMPACT THE AREA. BOTH THE ECMWF AND GGEM ARE CONSIDERABLY SLOWER WITH THIS NEXT SYSTEM. THIS LOOKS TO BE PRIMARILY A RAIN EVENT. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... HIGH PRESSURE WILL BUILD FROM THE WEST THROUGH THE TAF PERIOD. BKN VFR CIGS OVER ERN PA SHOULD MOVE INTO THE AREA EARLY THIS MORNING AND PERSIST THROUGH MOST OF THE DAY. CANNOT TOTALLY RULE OUT BRIEF TRANSITIONAL MVFR CIGS DURING LATE DAY OR EARLY EVENING...BUT CONFIDENCE LEVEL TOO LOW TO MENTION MORE THAN SCT025-035 DURING THAT TIME. N WINDS LESS THAN 10 KT SHOULD BECOME NW 5-10 KT THIS AFTERNOON... REMAINING RIGHT OF 310 MAGNETIC...THEN VEER NNW FRI NIGHT. .OUTLOOK FOR 06Z SAT THROUGH TUE... .LATE FRI NIGHT-SUNDAY MORNING...VFR. .SUNDAY AFTERNOON-MON MORNING...SNOW BECOMING LIKELY...WITH MVFR OR IFR CONDS. .MON AFTERNOON-TUE AFTERNOON...VFR. .TUE NIGHT...MVFR OR IFR CONDS POSSIBLE. SNOW IN THE EVENING...MIXING WITH OR CHANGING TO FREEZING RAIN AT KSWF/KHPN/KBDR...AND MIXING WITH OR CHANGING TO RAIN AT THE NYC METRO TERMINALS AND KISP. && .MARINE... LOW PRESSURE OFFSHORE WILL HELP CREATE SOME LONG PERIOD E AND S SWELLS AND KEEP SEAS AT OR A LITTLE ABOVE 5 FT FOR MOST OF THE TIME THROUGH FRIDAY. SCA CONTINUES THROUGH FRIDAY AFTERNOON...AND THIS MIGHT EVENTUALLY NEED TO BE EXTENDED IN TIME FOR THE EASTERN WATERS. HAVE LEFT IT AS A GENERAL SCA VS A SCA FOR HAZARDOUS SEAS FOR SIMPLICITY AND TO MATCH UP WITH SURROUNDING OFFICES. THE REST OF THE WATERS ARE EXPECTED TO HAVE SUB- SCA CONDS TONIGHT THROUGH FRIDAY NIGHT. INCREASING SW WINDS ARE EXPECTED TO BUILD SEAS TO SCA LEVELS ON THE COASTAL OCEAN WATERS LATE SUNDAY INTO MONDAY. NW FLOW BEHIND A COLD FRONT COULD PRODUCE GUSTS TO SMALL CRAFT LEVELS ON THE OCEAN WATERS ON MONDAY. && .HYDROLOGY... NO SIGNIFICANT PRECIPITATION EXPECTED THROUGH SATURDAY. THERE IS THE POTENTIAL FOR LIGHT TO POSSIBLY MODERATE LIQUID EQUIVALENT TO FALL FROM SUNDAY INTO MONDAY. AT THIS TIME NO SIGNIFICANT PRECIPITATION IS EXPECTED. ICE WILL CONTINUE TO DEVELOP ON LOCAL AREA RIVERS AND STREAMS AS TEMPS REMAIN WELL BELOW AVERAGE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ350- 353-355. && $$ SYNOPSIS...JC/DW NEAR TERM...JMC/JC/NV SHORT TERM...JC LONG TERM...DW AVIATION...GOODMAN/DS MARINE...JC/DW HYDROLOGY...JC/DW

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