Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 180543 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 143 AM EDT SAT APR 18 2015 .SYNOPSIS... A COLD FRONT WILL APPROACH ON SATURDAY AND PASS THROUGH BY EVENING. HIGH PRESSURE BUILDS BRIEFLY ACROSS THE AREA ON SUNDAY AND THEN GIVES WAY TO AN APPROACHING FRONTAL SYSTEM FROM THE SOUTHWEST ON MONDAY. A FRONTAL WAVE PASSES JUST SOUTH AND EAST OF THE AREA MONDAY NIGHT...FOLLOWED BY A COLD FRONTAL PASSAGE TUESDAY MORNING. A SERIES OF WEAK COLD FRONTS OR TROUGHS WILL MOVE THROUGH DURING THE MIDWEEK PERIOD FOLLOWED BY HIGH PRESSURE AT THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AT 01Z...THE TROUGH OF LOW PRES WAS ABOUT HALFWAY THROUGH THE FORECAST AREA. IT WILL CONTINUE TO TRACK SE THROUGH THE REMAINDER OF THE EVENING. CLEAR SKIES WILL DEVELOP BEHIND THE DEPARTING TROUGH. IN ADDITION...PATCHY FOG HAS DEVELOPED IN AREAS AWAY FROM THE CITY DUE TO TEMPS FALLING TO THE SFC DEW POINT...AND WILL INCLUDE PATCHY FOG FOR THOSE AREAS THROUGH AROUND DAYBREAK. GENERALLY EXPECTED LOWS TO RANGE FROM THE MID 50S IN THE NYC METRO AREA TO AS LOW AS THE LOW 40S INLAND AND ACROSS EASTERN LONG ISLAND. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... SAT LOOKS TO BE THE WARMEST DAY OF THE YEAR THUS FAR...WITH MOSTLY SUNNY SKIES...DEEP MIXING WITH H8 TEMPS +8 TO +10C...AND DOWNSLOPE WESTERLY FLOW...LEADING TO HIGHS WELL INTO THE 70S EVEN ALONG THE COAST...AND UPPER 70S WEST OF NYC. GUSTY WINDS WILL LIKELY BEGIN BY LATE MORNING. A POTENT NRN STREAM SHORTWAVE DIVING ACROSS UPSTATE NY AND NEW ENGLAND IN THE AFTERNOON WILL DRIVE A COLD FRONT THROUGH DURING THE EVENING. THIS FRONT WILL BE ACCOMPANIED BY A BAND OF HIGH-BASED STRATOCU AND A NOTICEABLE INCREASE IN WIND...WITH GUSTS 25-35 MPH. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... RIDGING BOTH ALOFT AND AT THE SFC TRANSLATES WEST TO EAST ACROSS THE AREA ON SUN. TO THE WEST...AN AMPLIFYING FULL LATITUDE TROF WILL LIFT NORTH AND EAST ACROSS THE GREAT LAKES AND INTO THE NE MON INTO TUE. GLOBAL MODELS IN PARTICULAR...THE 12Z GFS AND ECMWF...ARE IN RELATIVELY GOOD AGREEMENT WITH SMALL TIMING DIFFERENCES...BUT LARGER DIFFERENCES EXIST WITH QPF. THIS WILL RESULT IN AN APPROACHING FRONTAL SYSTEM THAT WILL HAVE BOTH ATLANTIC AND GULF MOISTURE TO WORK WITH. PWAT VALUES WILL BE ON THE ORDER OF 2SD ABOVE NORMAL. A FRONTAL WAVE IS FORECAST TO PASS JUST SOUTH OF THE AREA MON NIGHT...IN ESSENCE KEEPING THE AREA JUST NORTH OF THE WARM FRONT. THE COLD FRONT FOLLOWS TUE MORNING. STRONG WAA ON MON WITH A 50-60 KT SE LLJ WILL PRODUCE MODERATE TO OCCASIONALLY HEAVY RAIN FOR MUCH OF THE DAY. INSTABILITY ALOFT COULD ALSO RESULT IN SOME ELEVATED THUNDER MON NIGHT. RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE FORECAST...WITH THE HIGHEST AMOUNTS FROM NYC AND POINTS NORTH AND WEST. THE SE FLOW WILL ENHANCE OROGRAPHIC LIFT. GUST UP TO 25 TO 30 MPH WILL POSSIBLE AT THE SFC ON MON...BUT TEMP PROFILES WILL BE INVERTED LIMITING ANY STRONGER WINDS FROM COMING DOWN. CONDITIONS DRY OUT TUE INTO WED WITH A SERIES OF WEAK FRONTS AND/OR TROUGHS MOVING ACROSS THE REGION. THESE WILL REINFORCE A SEASONABLE AIRMASS. HIGH PRESSURE THEN FOLLOWS FOR THE END OF THE WEEK. UPPER AIR PATTERN WILL BE DOMINATED BY A BROAD...FLAT TROUGH EAST OF THE MS RIVER VALLEY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE FOR TODAY WITH A COLD FRONT PASSING THROUGH THIS EVENING. SOME FOG FOR KGON OVERNIGHT...OTHERWISE VFR THRU THE TAF PERIOD. LIGHT AND VARIABLE WINDS BCMG MOSTLY W...EXCEPT SW SEA BREEZES FOR KJFK/KISP/KBDR/KGON. KJFK PROBABLY SHIFTS S LATE AFTN. GUSTS 20-25 PRIMARILY IN THE AFTERNOON AND EVENING HOURS. WINDS SHIFT NW BY MIDNIGHT AND BECOME LESS GUSTY OVERNIGHT. .OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .SAT NGT...VFR WITH DECREASING WINDS. .SUN...VFR. SFC WND LIGHT NE BECOMING SE 10KT IN THE AFTN. .MON...MVFR BECOMING IFR. INCREASING ESE SFC WND. G30-35KT IN AFTN. .TUE...MVFR BECOMING VFR. G20-25KT. .WED...VFR BECOMING SUB VFR BY THE AFTN. && .MARINE... S-SW FLOW 10-15 KT AHEAD OF AN APPROACHING WEAK COLD FRONT BUILDING OCEAN SEAS GENERALLY TO 3 TO 4 FT ON THE ERN OCEAN WATERS THIS AFTERNOON AND EVENING. NEAR SHORE SCA CONDS MAY BE POSSIBLE ON ALL WATERS SAT AFTERNOON AND EARLY EVENING WITH THE APPROACH AND PASSAGE OF A COLD FRONT. HIGH PRESSURE BUILDS EAST OF THE WATERS LATE SUN AFT WITH AN APPROACHING FRONTAL SYSTEM FROM THE WEST. THIS WILL RESULT IN A STRENGTHENING SE FLOW SUN NIGHT INTO MON WITH SCA CONDITIONS LIKELY ACROSS ALL WATERS. SEAS WILL BUILD TO 7 TO 10 FT ON MON...THEN WILL BE SLOW TO SUBSIDE MON NIGHT INTO TUE. SUB-SCA CONDITIONS ARE EXPECTED ACROSS THE REMAINING WATERS LATE MON NIGHT INTO WED. && .FIRE WEATHER... DRY WEATHER...MINIMUM RH 20-30 PERCENT...AND WINDS GUSTING TO 25-35 MPH WILL LEAD TO ELEVATED POTENTIAL FOR FIRE GROWTH/SPREAD SAT AFTERNOON AND EARLY EVENING. SEVERAL WIND SHIFTS ARE EXPECTED THROUGH THE DAY...CREATING AN ADDITIONAL HAZARD WITH ANY ONGOING FIRES. INITIALLY NORTHWEST WINDS WILL SHIFT TO WEST- SOUTHWEST THEN SOUTHWEST THROUGH THE AFTERNOON...BEFORE RAPIDLY TURNING NORTHWEST AGAIN AROUND 6-7 PM WITH THE APPROACH/PASSAGE OF ANOTHER COLD FRONT. GUSTS MAY BRIEFLY STRENGTHEN AFTER THE COLD FRONTAL PASSAGE. A FIRE WEATHER WATCH IS IN EFFECT FROM 12 PM TO 8 PM GIVEN EXPECTED WEATHER CONDITIONS AND AFTER FEEDBACK FROM FIRE WEATHER OFFICIALS REPORTING DRY FUEL CONDITIONS. && .HYDROLOGY... THERE IS THE POTENTIAL FOR SIGNIFICANT RAINFALL WITH AN APPROACHING FRONTAL SYSTEM MONDAY INTO MONDAY NIGHT. STORM TOTAL RAINFALL WITH THIS SYSTEM WILL BE FROM 1 TO 2 INCHES...WITH THE HIGHEST AMOUNTS FROM NYC AND POINTS NORTH AND WEST. LOCALIZED HIGHER AMOUNTS WILL BE POSSIBLE IN THE HILLS NORTH AND WEST. 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. .COASTAL FLOODING... A PROLONGED PERIOD OF SE FLOW LATE SUN NIGHT INTO MON EVE WILL LIKELY RESULT IN WIDESPREAD MINOR COASTAL FLOODING. ASTRONOMICAL HIGH TIDES WILL BE RUNNING HIGH FOLLOWING A NEW MOON ON SAT. IN SOME CASES...DEPARTURES OF ONLY HALF A FOOT ABOVE NORMAL ARE NEEDED. STORM SURGE IS LIKELY TO PRODUCE WATERS LEVELS 1 TO 1 1/2 FT ABOVE NORMAL. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...FIRE WEATHER WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR CTZ005>012. NY...FIRE WEATHER WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR NYZ067>075-078>081-176>179. NJ...FIRE WEATHER WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR NJZ002-004-006-103>108. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION...JC MARINE... FIRE WEATHER... HYDROLOGY...

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