Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 160531 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 131 AM EDT THU APR 16 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE NORTHEAST THROUGH THURSDAY MORNING. THE HIGH THEN BUILDS OFFSHORE THURSDAY AFTERNOON AS A WEAK FRONTAL SYSTEM APPROACHES FROM THE WEST. A WEAK COLD FRONT MOVES THROUGH THE REGION ON FRIDAY. ANOTHER COLD FRONT WILL MOVE THROUGH SATURDAY NIGHT WITH HIGH PRESSURE BUILDING BEHIND IT ON SUNDAY. THE HIGH MOVES OFFSHORE SUNDAY NIGHT AS LOW PRESSURE APPROACHES FROM THE WEST...AFFECTING THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AREA STILL RECEIVING AN ABUNDANCE OF MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH INVERTED TROUGH SW OF THE AREA. THIS IS KEEPING TEMPERATURES SLIGHTLY HIGHER AS A RESULT OF A LITTLE MORE MIXED BOUNDARY LAYER. MINOR ADJUSTMENTS TO FORECASTS OF DEWPOINTS AND TEMPERATURES WERE MADE AS WELL TO BETTER MATCH OBSERVED TRENDS. OVERALL...FORECAST IS MAINLY ON TRACK. TEMPERATURES RUNNING A LITTLE HIGHER THAN FORECAST WILL EVENTUALLY RADIATIVELY COOL OFF FASTER OVERNIGHT. THEREFORE...MIN TEMPS WERE ONLY SLIGHTLY ADJUSTED FROM BEFORE. RIDGING BOTH ALOFT AND AT THE SFC BUILDS ACROSS THE AREA OVERNIGHT AND BECOME THE DOMINANT FEATURES. THIS WILL RESULT IN CLEARING SKIES AND A DIMINISHING NLY FLOW. OVERNIGHT LOWS WILL GENERALLY BE IN THE MID TO UPPER 30S IN THE SUBURBS...TO THE MID 40S NYC METRO. A FEW OF THE NORMALLY COLDER SPOTS WILL APPROACH THE FREEZING MARK. THIS IS NEARLY SEASONABLE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... HIGH PRESSURE BUILDS OFFSHORE THU AFT WITH A RETURN FLOW DEVELOPING FROM THE SE...THEN VEERING TO THE S/SW THU NIGHT AHEAD OF A WEAK FRONTAL SYSTEM. THE ONSHORE FLOW AND A SUBSIDENCE INVERSION WILL LIMIT THE DEPTH OF THE MIXED LAYER THU WITH READINGS ABOUT 5 TO 10 DEGREES COOLER THAN WED. HIGHS WILL GENERALLY BE IN THE MID 50S TO LOWER 60S...BUT EVEN COOLER ALONG THE SOUTH FACING SHORES. A SHORT WAVE TROF AND ASSOCIATED FRONTAL SYSTEM APPROACH FROM THE OHIO VALLEY THU NIGHT. THIS WILL RESULT IN INCREASING CLOUDS WITH THE CHANCES FOR SHOWERS INCREASING LATE AT NIGHT. EXPECT A WARMER NIGHT DUE TO THE CLOUD COVER AND ONSHORE FLOW...WITH LOWS IN THE 40S TO NEAR 50. RAINFALL AMOUNTS ARE EXPECTED TO BE LIGHT. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... THE LONG TERM PERIOD WILL START OUT A BIT UNSETTLED AS A COLD FRONT MOVES THROUGH FRIDAY. A QUICK MOISTENING OF THE ATMOSPHERE OCCURS FRIDAY MORNING AHEAD OF A SHORTWAVE TROUGH. SHOWERS ARE LIKELY DURING THE MORNING AND EARLY AFTERNOON HOURS AS THE FRONT CROSSES THE REGION. THE SHORTWAVE TROUGH AXIS AND COLD FRONT ARE FORECAST BY MUCH OF THE MODEL GUIDANCE TO BE EAST OF THE AREA BY 00Z SATURDAY...SO DRY CONDITIONS ARE FORECAST FRIDAY NIGHT. MODELS CONTINUE TO CONVERGE ON A DRY UPCOMING WEEKEND. THE FRONT THAT PASSES FRIDAY WILL NOT BRING MUCH OF AN AIR MASS CHANGE BEHIND IT FOR SATURDAY. WITH A NW FLOW SETTING UP ALOFT...TEMPERATURES WILL LIKELY RISE INTO THE LOWER 70S FOR MUCH OF THE REGION. SOME MIDDLE 70S ARE POSSIBLE IN THE NYC METRO AND NE NJ. ALOFT...A SHORTWAVE TROUGH WILL BE DIGGING INTO NORTHERN NEW ENGLAND SATURDAY. THIS KEEPS A SURFACE LOW PRESSURE WELL NORTH OF THE REGION. HOWEVER...THE ASSOCIATED COLD FRONT WILL MOVE THROUGH LATE IN THE DAY. MOISTURE AND LIFT WILL BE LACKING SO NO PRECIPITATION IS EXPECTED WITH THIS FRONT. DEEP UPPER LEVEL RIDGING BUILDS OVERHEAD SATURDAY NIGHT INTO SUNDAY. A SURFACE HIGH QUICKLY MOVES OVERHEAD SUNDAY MORNING...AND THEN OFFSHORE SUNDAY AFTERNOON. HIGH TEMPERATURES ON SUNDAY WILL LIKELY FALL ABOUT TEN DEGREES COOLER THAN SATURDAY DUE TO A COOLER AIR MASS AND ONSHORE FLOW SETTING UP IN THE AFTERNOON. WHILE THERE ARE TIMING AND AMPLITUDE DIFFERENCES AMONG THE NWP GUIDANCE...CONFIDENCE IN A PERIOD OF UNSETTLED WEATHER LATE SUNDAY NIGHT INTO TUESDAY CONTINUES TO RISE. A DEEPENING UPPER LEVEL TROUGH IN THE CENTRAL US WILL DEVELOP A SURFACE LOW ACROSS THE GREAT LAKES SUNDAY NIGHT INTO MONDAY...SENDING A FRONTAL SYSTEM TOWARDS THE REGION. LARGE SCALE LIFT AND MOISTURE INCREASES AS THE FRONT APPROACHES LATE SUNDAY NIGHT. A SECONDARY LOW MAY ALSO DEVELOP NEARBY SOMETIME MONDAY NIGHT OR TUESDAY MORNING FURTHER ENHANCING LIFT. HAVE INCREASED POPS TO HIGH CHANCE WITH THIS PACKAGE...BUT WILL LIKELY HAVE TO BE INCREASED IN SUCCESSIVE FORECASTS AS TIMING BECOMES MORE CLEAR. THIS SYSTEM HAS THE POTENTIAL TO BRING A WIDESPREAD HALF TO ONE INCH OF RAIN. THE SYSTEM SHOULD MOVE EAST OF THE AREA BY WEDNESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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HIGH PRESSURE WILL BUILD INTO THE REGION THIS MORNING...THEN OFFSHORE THIS AFTERNOON. VFR THROUGH THE TAF PERIOD. LIGHT AND VARIABLE AWAY FROM KNYC TERMINALS...WHERE PREVAILING FLOW WILL TEND TO THE N/NNE THROUGH 12Z. SE WINDS DEVELOP THIS MORNING...THEN INCREASE TO AROUND 10KT AFTER 16-19Z. WINDS TURN MORE SOUTHERLY AFTER 19Z. SPEEDS DECREASE AFTER 00Z. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .THURSDAY NIGHT...VFR. .FRIDAY...MVFR CONDS POSSIBLE IN -SHRA. .FRIDAY NIGHT...IMPROVING CONDITIONS. .SATURDAY...MAINLY VFR. .SUNDAY...VFR. .MONDAY...MVFR CONDS POSSIBLE IN -SHRA.
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&& .MARINE... FORECAST ON TRACK TONIGHT. HIGH PRESSURE WILL BUILD ACROSS THE WATERS LATE TONIGHT INTO THU MORNING BEFORE MOVING PASSING TO THE EAST. SUB SCA CONDITIONS CONTINUE THROUGH THURSDAY NIGHT. A WEAK COLD FRONT MOVES ACROSS THE WATERS ON FRIDAY. A FEW WIND GUSTS TO 20 KT ARE POSSIBLE AND SEAS MAY BUILD TO 4 FT. CONDITIONS SHOULD STAY BELOW SCA LEVELS HOWEVER. SUB SCA CONDITIONS ARE THEN EXPECTED THROUGH THE WEEKEND. INCREASING EASTERLY FLOW ON MONDAY AHEAD OF ANOTHER FRONTAL SYSTEM WILL BRING SCA CONDITIONS TO THE OCEAN WATERS...AND POTENTIALLY THE SOUND AND NEAR SHORE WATERS. && .FIRE WEATHER... WINDS ARE DIMINISHING BUT LOW LEVEL RH REMAINS IN THE 15 TO 25 PERCENT RANGE. THESE RH LEVELS WILL EVENTUALLY INCREASE TO 30 TO 50 PERCENT BY LATE THIS EVENING. && .HYDROLOGY... A FEW TENTHS OF AN INCH OF RAIN IS FORECAST ON FRIDAY. A MORE SIGNIFICANT RAINFALL IS POSSIBLE EARLY NEXT WEEK WITH POTENTIAL FOR 0.5 TO 1 INCH OF RAIN. 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. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...DS/DW NEAR TERM...JM/DW SHORT TERM...DW LONG TERM...DS AVIATION...BC MARINE...DS/DW FIRE WEATHER... HYDROLOGY...DS/DW

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