Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181143 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 743 AM EDT SAT APR 18 2015 .SYNOPSIS... A COLD FRONT APPROACHES TODAY AND MOVES ACROSS THE AREA THROUGH THIS EVENING. HIGH PRESSURE BUILDS OVER THE AREA SUNDAY AND MOVES OFFSHORE LATE IN THE DAY AS A FRONTAL SYSTEMS APPROACHES FROM THE SOUTHWEST. A FRONTAL WAVE PASSES OVER OR RIGHT BY THE AREA MONDAY NIGHT...FOLLOWED BY A COLD FRONTAL PASSAGE LATE AT NIGHT INTO 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 PM THIS EVENING/... FORECAST REMAINS ON TRACK...THE WARMEST DAY OF THE YEAR ON TAP WITH THE COMBINATION OF MOSTLY SUNNY SKIES...DEEP MIXING...850 MB TEMPS RANGING FROM +8C TO +10C...AND DOWNSLOPING WESTERLY FLOW. HIGHS TODAY WILL RANGE FROM THE UPPER 70S TO AROUND 80 FOR NYC AND MOST AREAS ALONG AND WEST OF THE HUDSON RIVER...AND IN THE MID 70S FOR INTERIOR PORTIONS OF SOUTHERN CT AND THE REST OF THE LOWER HUDSON VALLEY. FOR LONG ISLAND...COASTAL CT...AND COASTAL PORTIONS OF NYC...HIGHS WILL TOP OFF IN THE LOW 70S. A COLD FRONT APPROACHES LATER IN THE DAY...ALLOWING FOR WINDS TO SHIFT FROM A SW FLOW TO MORE OF A WESTERLY FLOW. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... COLD FRONT MOVES ACROSS THE REGION THIS EVENING. WINDS MAY INCREASE TO 15-20 MPH WITH 20-30 MPH WITH ITS PASSAGE...BUT WINDS DIMINISH AS THE EVENING PROGRESSES...AND WINDS WILL SHIFT TO THE NORTH AT 5-10 MPH BY MIDNIGHT TONIGHT. THE FRONT SHOULD COME THROUGH DRY...WITH THE EXCEPTION OF SOME MID-LEVEL CLOUDS WITH ITS PASSAGE. HIGH PRES OVER EASTERN CANADA WILL DROP INTO THE GULF OF MAINE WITH THE CENTER OF THE HIGH JUST EAST OF CAPE COD ON SUNDAY. AS A RESULT...WINDS WILL SHIFT TO THE SOUTHEAST...USHERING A MUCH COOLER AND MORE SEASONAL AIRMASS INTO THE REGION. HIGHS ON SUNDAY WILL TOP OFF IN THE MID 50S TO LOW 60S...EXCEPT FOR LONG ISLAND AND COASTAL CT...WHERE HIGHS WILL ONLY BE IN THE LOW 50S. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... AN AMPLIFYING FULL LATITUDE TROF WILL LIFT NORTH AND EAST ACROSS THE GREAT LAKES AND INTO THE NE SUN NIGHT INTO TUE. 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. THE 00Z GLOBAL MODELS HAVE SPED UP THE TIMING OF THIS SYSTEM BY A LITTLE...BUT STILL SOME DIFFERENCES REGARDING PLACEMENT OF HIGHER RAIN AMOUNTS. A FRONTAL WAVE IS FORECAST TO PASS OVER OR NEARBY JUST THE AREA MON NIGHT...IN ESSENCE KEEPING THE AREA NEARBY DECENT LIFT. LIFT WILL BE ENHANCED...ESPECIALLY OVER THE EASTERN HALF OF THE CWA...BY FRONTOGENETIC FORCING AND A 50-60 KT SE LLJ LATE SUN NIGHT INTO EARLY MON MORNING. THINKING IS THAT EASTERN ZONES WILL PROBABLY END UP WITH HIGHER RAIN AMOUNTS IN GENERAL. INSTABILITY ALOFT COULD ALSO RESULT IN SOME ISOLATED ELEVATED THUNDER MON NIGHT...WHICH WOULD ADD TO THE VARIABILITY AND SOME UNCERTAINTY WITH THE HIGHEST RAIN AMOUNTS FOR THE TRI STATE AREA. RAINFALL AMOUNTS OF 1 TO 1.5 INCHES ARE FORECAST...WITH THE HIGHEST AMOUNTS OVER LONG ISLAND AND CT. UP TO 2 INCHES LOCALLY IS STILL POSSIBLE. THE SE FLOW PROBABLY ENHANCES OROGRAPHIC LIFT...SO FORECAST AMOUNTS NW OF THE CITY COULD BE A LITTLE TOO LOW. SO IN GENERAL...RAIN BECOMES LIKELY LATE SUNDAY NIGHT FOR MOST SPOTS...WITH MODERATE TO POTENTIALLY BRIEFLY HEAVY RAIN MONDAY MORNING. MID LEVELS DRY OUT MONDAY AFTERNOON...SO LIGHT RAINFALL OR POSSIBLY EVEN DRIZZLE WOULD BE EXPECTED BY LATE IN THE DAY. LIGHT RAIN REMAINS LIKELY MONDAY NIGHT AS A WEAK LOW PRESSURE WAVE CENTER MOVES THROUGH. SOME FOG DEVELOPMENT EXPECTED MON NIGHT AS WELL WITH WINDS BECOMING LIGHTER AND PLENTY OF MOISTURE AROUND. GUSTS 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 /12Z SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE FOR TODAY WITH A COLD FRONT PASSING THROUGH THIS EVENING. 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 12Z SUNDAY THROUGH WEDNESDAY... .SUN...VFR. SFC WND LIGHT NE BECOMING SE 10KT IN THE AFTN. .SUN NIGHT...RAIN/SUB VFR/LLWS DEVELOPING LATE. E G25-30KT LATE. .MON...MVFR/IFR. RAIN. LLWS EARLY. INCREASING ESE SFC WND. G30KT. .TUE...MVFR BECOMING VFR. WEST G25KT. .WED...VFR. CHC SUB VFR IN THE AFTN. SW G25KT. && .MARINE... A COLD FRONT APPROACHES THE WATERS LATER THIS AFTERNOON AND MOVES ACROSS THIS EVENING. GENERALLY SUB-SCA CONDS...BUT A FEW NEARSHORE GUSTS TO 25 KT ARE POSSIBLE THIS AFTERNOON. 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 25-30 MPH WILL LEAD TO ELEVATED POTENTIAL FOR FIRE GROWTH/SPREAD THIS 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 RED FLAG WARNING IS IN EFFECT FOR THE WHOLE CWA FROM 12 PM TO 8 PM GIVEN EXPECTED WEATHER 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 1.5 INCHES...WITH THE HIGHEST AMOUNTS GENERALLY OVER LONG ISLAND AND CT. LOCALIZED HIGHER AMOUNTS WILL BE POSSIBLE. 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. && .TIDES/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...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR CTZ005>012. NY...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR NYZ067>075-078>081-176>179. NJ...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR NJZ002-004-006-103>108. MARINE...NONE. && $$ SYNOPSIS...JC/MPS NEAR TERM...MPS SHORT TERM...MPS LONG TERM...JC/DW AVIATION...JC MARINE...JC/MPS FIRE WEATHER... HYDROLOGY...JC/MPS TIDES/COASTAL FLOODING...

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