FXUS61 KOKX 201739 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 1239 PM EST TUE JAN 20 2009 .SYNOPSIS... LOW PRESSURE DEEPENING EAST OF THE CAROLINAS THIS AFTERNOON... WILL TRACK WELL SOUTH AND EAST OF LONG ISLAND THROUGH TONIGHT. HIGH PRESSURE THEN BUILDS TOWARDS THE REGION FROM THE SOUTHWEST WEDNESDAY AND WEDNESDAY NIGHT...AND SLIDES SOUTH THURSDAY AND THURSDAY NIGHT. A WARM FRONT WILL LIFT THROUGH THE TRI-STATE AREA FRIDAY FOLLOWED BY A COLD FRONT FRIDAY NIGHT. ARCTIC HIGH PRESSURE THEN BUILDS IN FOR THE WEEKEND. A WARM FRONT APPROACHES FROM THE SOUTH ON MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AIRMASS COLDER THAN ADVERTISED BY A FEW DEGREES...LIKELY DUE TO A LARGE SNOW PACK UPSTREAM AND THE FRESH SNOW THAT FELL ACROSS THE REGION ON SUNDAY. FORECASTS HAVE BEEN ADJUSTED ACCORDINGLY. 12Z MODEL DATA AND WATER VAPOR IMAGERY CONTINUE TO SUPPORT A STRONG POSITIVELY TILTED TROUGH OVER THE EASTERN U.S. THIS WILL KEEP THE DEEPENING LOW JUST EAST OF THE CAROLINAS THIS MORNING ON A TRACK TO THE RIGHT OF THE BENCHMARK THIS EVENING (40N...70W). NO PCPN EXPECTED OVER LAND AREAS WITH THIS STORM SYSTEM...BUT PERHAPS SOME HIGH CLOUDINESS ON ITS NORTHERN PERIPHERY. WILL MAINTAIN SLIGHT CHANCE POPS ACROSS THE FAR EASTERN OCEAN WATERS AS VORT ENERGY IN THE NORTHERN BRANCH OF THE POLAR JET INTERACTS WITH FRINGE MOISTURE...POSSIBLY PRODUCING SCT FLURRIES/ISOLATED SNOW SHOWERS. OTHERWISE...AFTERNOON INSTABILITY CU EXPECTED WITH TROUGH OVER THE REGION. WEAK CAA ON GUSTY NORTHERLY FLOW AND AFTERNOON CU WILL KEEP TEMPS ABOUT 5 DEGREES BELOW SEASONABLE TODAY. MID/UPPER 20S INTERIOR...LOWER 30S CITY/COAST. N/NW WINDS OF 10 TO 20 MPH THIS AFTERNOON AND CONTINUE THROUGH OVERNIGHT AS PRESSURE GRADIENT TIGHTENS BETWEEN OFFSHORE LOW AND HIGH PRESSURE OVER THE MID-ATLANTIC. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... UPPER TROUGH AXIS GRADUALLY SWINGS ACROSS THE REGION TONIGHT INTO WED. ANY FLURRIES/SCT SNOW SHOWERS SHOULD COME TO AN END ACROSS EASTERN SECTIONS TONIGHT WITH DECREASING CLOUDS TOWARDS DAYBREAK. TEMPS FALL INTO TEENS CITY/COAST AND SINGLE DIGITS INTERIOR TONIGHT...WHICH COMBINED WITH THE GUSTY FLOW CLOUD HAVE WIND CHILLS AROUND 0 TO -5 ACROSS FAR INTERIOR LATE TONIGHT/EARLY WED AM. WEAK SHORTWAVE SLIDES SE TOWARDS THE REGION ON BACKSIDE OF THE TROUGH WED AFTERNOON...WITH INCREASING HIGH/MID CLOUDS BUT DEEP NW FLOW SHOULD KEEP THINGS DRY. HIGH TEMPS GENERALLY IN THE MID TO UPPER 20S WED WITH LIMITED MIXING UNDER STRENGTHENING SUBSIDENCE INVERSION AND AFTERNOON CLOUDS. GUSTY NW WINDS CONTINUE INTO WED AFTERNOON. UPPER FLOW BECOMES MORE ZONAL THURS AS TROUGH SLIDES OFFSHORE. HIGH PRESSURE SLIDES E ACROSS THE SOUTHERN US. DEVELOPING DEEP WSW FLOW WITH RISING HEIGHTS ALOFT WILL ALLOW FOR DRY CONDITIONS AND MODERATING TEMPERATURES ON THURSDAY. ANOTHER WEAK SHORTWAVE RACING THROUGH IN THE FLOW WILL BRING ANOTHER PERIOD CLOUDS THURSDAY BUT AGAIN DRY. HIGHS THURSDAY SHOULD APPROACH NORMAL LEVELS WITH MID 30S EXPECTED EXCEPT IN THE INTERIOR LOWER HUDSON VALLEY WHERE HIGHS SHOULD BE IN THE LOWER 30S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... EC/GFS SIMILAR WITH OVERALL FEATURES. UPPER RIDGE OUT WEST FINALLY BREAKS DOWN...ALLOWING FOR LOWERING HEIGHTS...AND A FAST ZONAL PATTERN ACROSS MUCH OF THE CONUS. STILL OBSERVE LOW HEIGHTS ACROSS THE NORTHEAST...WITH NEXT SHORTWAVE TRAVERSING ACROSS SOUTHERN CANADA...AND MOVING ACROSS THE NORTHEAST THIS WEEKEND. THIS FEATURE WILL RESULT IN ANOTHER COLD SHOT WITH WELL BELOW NORMAL TEMPS BY SATURDAY. AT THE SURFACE...LOW PRESSURE MOVES WELL TO THE NORTH...ACROSS NORTHERN NEW ENGLAND BY FRIDAY OUT AHEAD OF THE SHORTWAVE. WEST TO SOUTHWEST WINDS PERSIST THROUGH FRIDAY. THEN THIS LOW WILL DRAG A COLD FRONT THROUGH FROM NORTHWEST TO SOUTHEAST FRIDAY NIGHT. SOME TIMING DIFFERENCES NOTED AS GFS FASTER TRACKING THIS FRONT EAST AS COMPARED TO EC. WINDS SHIFT AROUND TO THE NORTHWEST...AND MUCH COLDER AIR MOVES IN. ON FRIDAY IN THE WEST/SOUTHWEST FLOW...TEMPS WILL WARM INTO THE 30S AND LOWER 40S. THEN WE WILL SEE A BIG DROP IN TEMPS SATURDAY WITH READINGS IN THE MID AND UPPER 20S. STILL CHILLY SUNDAY...THEN SLIGHT MODERATION IN TEMPS CAN BE EXPECTED MONDAY AS NEXT SYSTEM MOVES OUT OF THE MID WEST...AND A WARM FRONT APPROACHES. SLIGHT CHANCE FOR SOME RAIN (DEPENDING ON TIME OF DAY) AND SNOW SHOWERS FRIDAY AHEAD OF THE FRONT. MAINLY DRY THROUGH SATURDAY AS THE FRONT CLEARS THE AREA. NEXT AND BETTER CHANCE FOR PRECIP IS ON MONDAY AS THE AFOREMENTIONED WARM FRONT APPROACHES. LOOKS LIKE POTENTIAL WINTRY MIX WITH THIS FEATURE. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... VFR WITH MAINLY HIGH CLOUDS...KGON THOUGH COULD SEE SOME OCCASIONAL LOW END VFR CEILINGS OVER NEXT FEW HOURS. WITH BOUNDARY LAYER BECOMING WELL MIXED...WILL NOT SEE A LOT IN THE WAY OF GUSTINESS...SO BUMPED UP WINDS TO AROUND 15KT OUT OF THE N (MIGHT SEE AN OCCASIONAL GUST TO 20KT BUT MORE LIKELY ONLY A FEW KT ABOVE THE SUSTAINED SPEED). WINDS DIMINISH TO AROUND 12T OUT OF THE NW AROUND MIDNIGHT...THEN BECOME W AROUND 10 KT TOWARDS MIDDAY TOMORROW. OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... A WARM FRONT MAY BRING SUB-VFR CONDITIONS IN MIXED PRECIPITATION ON FRI. A COLD FRONT WILL FOLLOW FRI NIGHT...AND SNOW SHOWERS WITH SUB-VFR CONDITIONS ARE POSSIBLE FRI NIGHT INTO SAT...THEN VFR FOR THE BALANCE OF THE WEEKEND. && .MARINE... SE SWELL CONTINUES TO PRODUCE SEAS OF 5 FT ON THE OCEAN WATERS. THUS...WILL MAINTAIN SCA ON THE OCEAN WATERS...AND THEN CONTINUE INTO TONIGHT FOR MARGINAL 25-KT GUSTS AND 5-FT SEAS ONLY ON THE OCEAN AND MAINLY FARTHER OFFSHORE AS LOW PRESSURE PASSES WELL SE OF LONG ISLAND. CONDITIONS IMPROVE WED MORNING WITH THE APPROACH OF SURFACE HIGH PRESSURE. WESTERLIES ON THE BACK SIDE OF THE RIDGE AND AHEAD OF A COLD FRONT DROPPING SE ACROSS EASTERN CANADA RAMP WINDS BACK UP ON THU...WITH SCA CONDITIONS EXPECTED ON THE OCEAN WATERS AND THE EASTERN SOUND. MARGINAL SCA CONDITIONS ARE EXPECTED ON THE OCEAN THU NIGHT AND FRI AS THE PRESSURE GRADIENT REMAINS FAIRLY TIGHT. W-SW WINDS THROUGH FRIDAY SHIFT AROUND TO NW ON SAT AS A COLD FRONT MOVES THROUGH. WINDS WILL BE GUSTY...AND SCA CONDITIONS ARE LIKELY. WINDS DIMINISH SLIGHTLY ON SUNDAY. && .HYDROLOGY... NO SYSTEM OF HYDROLOGIC IMPACT IS EXPECTED THROUGH AT LEAST THE WEEKEND. WITH THE PROLONGED COLD PERIOD...ICE WILL BUILD ON THE AREA RIVERS...WITH THE POTENTIAL FOR LOCALIZED ICE JAM FLOODING (PENDING A THAW). && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...DW/NV NEAR TERM...DW/NV SHORT TERM...NV LONG TERM...PW AVIATION...MALOIT MARINE...DW/BG HYDROLOGY...NV