Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 252330 AFDALY Area Forecast Discussion National Weather Service Albany NY 730 PM EDT Thu May 25 2017 .SYNOPSIS... Showers this afternoon will diminish from south to north. A break in the precipitation this afternoon into the evening may allow for some gusty winds to impact portions of the Taconics, Berkshires and southern Vermont this afternoon. Then a coastal storm takes shape tonight with additional periods of rain expected overnight into early Friday. The holiday weekend starts off mainly dry and seasonable before the threat for showers and possibly a few thunderstorms returns late Sunday into Monday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A Wind Advisory remains in effect the northern and central Taconics Berkshires and Bennington and western Windham Counties in southern VT until 9 PM EDT... Rain in eastern Ny and western New England keeps shifting north and not much other rain in the region. Additional rain south of the region also feeding north and some additional development and coverage possible later this evening and through the night. Some minor adjustments to temperatures and rain chances through this evening based on data and trends. Previous AFD has more details and is below... As of 330 pm, upper low centered near the OH/WV/KY triple point is readily visible on water vapor imagery. Deep moisture plume along the eastern periphery of the circulation has mainly pushed north and east of the forecast area, along with an area of steadier rainfall that worked through the region earlier. Drier midlevel air evident on is working in from the south, resulting in rainfall becoming more showery. Overall, shower coverage will continue to be on a downward trend from south to north as this drier air spreads into the region, so have tapered PoPs to chance accordingly. Still enough lower-level moisture and lift to account for at least scattered coverage of showers through the remainder of the evening, especially along favored eastern- facing slopes of the higher terrain due to the southeasterly low-level jet. Advisory-level winds have thus far failed to materialized, but no changes are planned to the wind advisory. As precip coverage diminishes, there is the chance for slightly deeper mixing to occur, although the depth of mixing is in question due to the strong inversion in place. 50 kt winds just above the inversion depicted on current KENX radar at around 3.5-4 kft MSL suggests potential for advisory-level gusts remains. Tonight, the upper low center will reorient itself and become located just south of Long Island by 06Z. Deformation in the northwest quadrant of the low and a trowal signature in the 700-500 mb theta-e fields is likely to result in an uptick in precipitation coverage, especially after midnight and along and east of the Hudson Valley where categorical PoPs remain in place. Kept isolated thunder in the forecast as showalter values go slightly negative. Wind concerns should quickly diminish after the advisory expires as the midlevel height gradient becomes baggier in conjunction with the approach of the midlevel circulation center. With plenty of cloud cover in place, lows tonight in the upper 40s to low 50s will be slightly above seasonal normals. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... The upper circulation slowly moves into the Gulf of Maine on Friday. This should result in a diminishing trend in the precipitation, but with cyclonic flow persisting still expect plenty of clouds and at least the possibility for a few showers much of the day. With the cloud cover in place, high temps are expected to run around 10F below seasonal normals, with the possible exception of the far south which stands the best chance to briefly break out of the overcast later in the day. Very weak ridging at the surface and aloft attempts to build into the region Friday night, which may result in at least a partial clearing trend. Lows near normal. Saturday into Saturday night, quasi-zonal to slightly northwesterly upper flow with weak high pressure at the surface argue for a mainly dry period. However, the subsidence signal is not strong, and the NWP suite amplifies the flow a bit with a positively-tilted shortwave toward 00Z Friday. A few light showers are not out of the question toward southern portions of the forecast area, so have slight chance PoPs creeping into the Catskills/Mid-Hudson Valley Saturday evening and expanding into the Berkshires/NW CT Saturday night. Will have to watch to see if a more amplified/wetter trend continues, but for now still think this period will be mainly dry. Partial sunshine will allow temps to return to near seasonable normals. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Upper cut off expected to track slowly across southern Canada just north of the Great Lakes through the period. There could be a period of dry weather Sunday until the upper energy gets closer to our region but the onset of scattered showers and isolated thunderstorms should begin by midday and coverage will increase toward evening. The clouds and approaching rain will keep highs in the upper 60s to lower 70s. On Monday, warm advection ahead of a slowly advancing cold front will support more clouds and increasing coverage of showers and scattered thunderstorms. Even with the clouds and showers, warming boundary layer temperatures will support highs Monday in the upper 60s to lower 70s. Boundary layer flow is expected to be west southwest, which could limit the coverage a bit but we will see as we get closer. Sources of guidance show little pieces of upper energy tracking through our region through the southern periphery of the upper cut off Tuesday through Thursday. The first phase of the cold front tracks through later Tuesday and there may be a period of less coverage of clouds and showers during the morning Tuesday allowing temperatures to reach the mid to upper 70s but mid 60s to around 70 northern areas. Better coverage of showers and thunderstorms is expected Tuesday afternoon and night but again, west to southwest boundary layer flow may limit coverage a bit. Boundary layer temperatures cool steadily Wednesday and Thursday as temperatures aloft cool a bit more rapidly proximate to the upper low. The proximity to pieces of upper energy tracking through the southern periphery of the upper low and the cold air aloft should support scattered showers each day, especially each afternoon with the daytime heating and instability. Highs Wednesday in the upper 60s to lower 70s with some mid 70s southern areas and lower to mid 60s northern areas. Highs Thursday in the uper 60s to lower 70s but around 60 to lower 60s northern areas.ay afternoon/evening with some surface based instability, decent mid-level thermodynamics and kinematic fields. However, there is a chance that cool, stable air remains across at least portions of the region, as the warm front may get hung up, especially if an offshore surface wave develops as pronounced as some guidance suggests. Chance for thunderstorms will depend greatly on if and when the warm front moves through the region. GFS/ECMWF are hinting at another secondary front moving through the region on Tuesday with a chance for showers and thunderstorms yet again. Temperatures are tricky for Monday, again highly dependent on if the warm front clears the region. For now, have leaned on the cooler side of guidance, with 60s for most higher elevations, and lower 70s in valleys, but should the warm front move through, temperatures across portions of the region could be at least 5-10 degrees warmer. Overnight lows mainly in the 50s. Tuesday highs should reach the mid/upper 70s for lower elevations, and 65-70 across higher terrain. Wednesday/Thursday, it appears that upper level cyclonic flow and possible embedded upper level impulses may keep at least scattered showers/isolated thunderstorms across portions of the region, with greatest chances north of I-90. Some small hail/gusty winds could occur with any convection given cold air aloft and a fairly strong mid/upper level wind field. Highs should be in the mid 60s to lower 70s, although may be cooler Thursday behind a reinforcing cold front. Lows should range from the mid 40s across higher terrain, to the lower/mid 50s in valley areas. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Low pressure near the Delmarva region will move northeast to Long Island and southern New England tonight, and then will move slowly east of New England tomorrow. Rain in the KALB, KPSF and KGFL areas will continue through tonight with mainly MVFR ceilings and visibilities but some brief periods of IFR in heavier rain and even some VFR possible in lulls in the rain. Rain may slowly decrease in coverage and intensity Friday but ceilings and visibilities should continue to be predominantly MVFR. Winds aloft have weakened so there should not be any wind shear. Generally north to east winds at 10 Kt or less this evening but gusts over 15 Kt this evening at KPSF. Winds becoming north to northwest Friday at 10 Kt or less. Outlook... Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Slight Chance of SHRA. Sunday Night: High Operational Impact. Likely SHRA. Memorial Day: Moderate Operational Impact. Chance of SHRA...TSRA. Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday: Moderate Operational Impact. Scattered SHRA...TSRA. && .FIRE WEATHER... Showers tonight into early Friday will become less widespread during the afternoon, but still expect a cloudy, cool, and damp day. Slightly warmer and drier Saturday with light northwesterly winds. A few showers are possible Sunday with more widespread activity occurring Sunday night into early Memorial Day. && .HYDROLOGY... Radar estimates suggest a tenth to around a half inch of rainfall has occurred today as of mid-afternoon. After a lull into this evening, a developing system off the coast will likely bring more rainfall to the region, with up to another half inch possible. Locally higher amounts could occur along eastern-facing slopes of the higher terrain. Storm total amounts should range from around a half into to an inch. While river flooding is not expected, the Hudson River at Poughkeepsie will briefly approach flood stage around 06Z tonight. Showers should taper off through the day on Friday, with only light amounts expected. The next potential for widespread rainfall is expected Sunday night into Memorial Day. 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 website. && .EQUIPMENT... The ASOS in Glens Falls at the Floyd Bennett Memorial Airport will experience outages until communications are fully restored. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Wind Advisory until 9 PM EDT this evening for NYZ054-061. MA...Wind Advisory until 9 PM EDT this evening for MAZ001-025. VT...Wind Advisory until 9 PM EDT this evening for VTZ013-014. && $$ SYNOPSIS...Thompson NEAR TERM...NAS/Thompson SHORT TERM...Thompson LONG TERM...NAS AVIATION...NAS FIRE WEATHER...Thompson HYDROLOGY...Thompson EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.