Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 210250 AFDALY Area Forecast Discussion National Weather Service Albany NY 1050 PM EDT Tue Mar 20 2018 .SYNOPSIS... A storm system organizing over the mid-Atlantic region will move off the eastern seaboard tonight, allowing for a moderate to heavy snow for areas mainly south interstate 90 and east of interstate 87. Behind this storm, dry and cold weather will continue into the upcoming weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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As of 1045 pm EDT...Mid and high clouds will continue to increase from the south and west of the Capital Region, as the next storm system moves closer to the region. The latest clean longwave IR channel /10.35 micron/ continues to show the canopy of clouds south and east of the I-90 corridor. Temps have dropped off a bit where the cirrus have thinned. The 00Z KALY soundings remains bone-dry with a PWAT of 0.11". The cirrus shows up nicely above 500 hPa. Lows will range from the single digits and teens from the Capital District north and west with lower to mid 20s south and east. We also pushed back the timing of the light snow reaching the mid Hudson Valley and NW CT based in the latest 3-km HRRR/NAM nest towards sunrise.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Surface wave developing along the east coast of Virginia this afternoon is bringing snow to portions of Maryland and southern Pa. This wave will shift east later today and tonight with associated precipitation moving east off the east coast and remaining south of our area. The main mid-to-upper level dynamics will approach the east coast on Wednesday with another surface low forecast to develop along the east coast early in the day. This surface cyclone will develop just east of the Delmarva peninsula early Wednesday then drift slowly east northeast becoming vertically stacked with mid-level low pressure south of Long Island. Strong upper level dynamics will combine with a band of mid-level frontogenesis and reduced lapse rates around the north edge of a closed 700 mb cyclone to set the stage for bands of moderate to heavy snow across southeast NY Wednesday afternoon into the evening. The main questions for our area will center around how far north significant snow can reach into Hudson Valley and southern New England. Model guidance is coming into better agreement with this storm and forecast confidence is slowly increasing. Last night`s 00z NAM appears to be an outlier bringing heavier precipitation north to the Capital District, although a few SREF members from the 09z run today are still showing some heavier amounts reaching as far north as ALB while the GEFS has a few members with as much as 0.1 to 0.20 inches of QPF at ALB. GEFS spread at POU is still rather large with values ranging from 0.10 to 1.0 inches and the majority of members clustered around 0.5 inches. SREF snowfall amounts at POU are mostly clustered between 5 and 10 inches. Finally, the latest ECMWF has come in a bit lighter and further south with the heavier QPF than many of these models indicating that heavy snow in our area could be confined to southern Dutchess and southern Litchfield Counties, and points southward. To summarize, a majority of our operational models and ensemble members continue to indicate that warning criteria snowfall with amounts from 5 to 10 inches is a good possibility from Dutchess to Litchfield Counties, however a fairly rapid drop- off in snow is expected farther north with most likely accumulations in the Capital District around or less than an inch Areas north and west of the Capital District will get no snow. Have edited grids to reflect these trends. Behind the storm, dry and cold weather will continue for Thursday, with highs mainly in the 30s and lows in the teens and 20s, along with a partly cloudy sky. An upper low will drop south across and south of the area on Friday with limited moisture and scattered snow showers mainly across the higher terrain west of the Hudson Valley. && .LONG TERM /FRIDAY THROUGH TUESDAY/... The mean longwave trough over the eastern CONUS and the Northeast will continue in the long term with below normal temperatures. Friday night into Saturday...The cold pool of the H500 upper level low drifts south and east of the region. Short-wave energy in the northerly flow may focus some isolated snow showers and flurries especially north of the Capital Region tied to the diurnal heating. H850 temps remain in the -10C range. Lows Friday night will be in the teens to mid 20s, and highs will be in the upper 20s to mid 30s over the hills and mtns, and upper 30s to lower 40s in the valleys. These temps will be around 10 degrees or so below normal Saturday night into Sunday...A large sfc Canadian anticyclone /1040 hPa/ attempts to ridge in from north-central Quebec. A sfc trough pivots through the region based on the 12Z ECMWF/GFS/GEFS for isolated snow showers and flurries at night. A few may linger south and east of the Tri Cities during the late morning and early afternoon. Lows will be similar to Fri night, and highs will be a tad warmer than Saturday by a few degrees. Sunday night into Tuesday...A high amplitude ridges builds in from the Southeast through the Great lakes Region and into eastern Canada. The H500 ridge folds over into the Northeast and the Canadian Maritimes early in the week with a big cutoff cyclone off the East Coast. Fair and cold/cool weather is likely into Tuesday, unless the oceanic cyclone backs westward. Temps moderate slightly, but will still be below normal with highs possibly reaching the mid and upper 40s in the valleys on Tuesday, and mid 30s to lower 40s over the higher terrain. A cold front may bring some rain and snow showers into the forecast area Tue night into Wednesday. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... High pressure will continue to ridge in from southern Quebec tonight into tomorrow. Low pressure will move northeast from near the Delmarva region tonight into tomorrow morning, and then slowly moves east to northeast well south of Long Island in the afternoon to early evening. VFR conditions for all the TAF sites prior to 12Z/WED. The mid to high clouds continue to thicken and lower from south to north across eastern NY and western New England. Some light snow may break out near KPOU between 11Z-14Z/WED. Conditions rapidly deteriorate at KPOU in the late morning into the afternoon with light to moderate snow with IFR/LIFR conditions. Some of the light snow may reach KPSF by 19Z, and expect MVFR to IFR conditions with perhaps some reductions to LIFR in moderate snow in the afternoon. Further north towards KALB/KGFL it will take some time for the cloud bases to lower and the column to saturate. A PROB30 group was used for KALB from 18Z-00Z/THU with perhaps MVFR vsbys. The winds will light from the north to northeast at 4-7 kts tonight, but will then increase in the late morning to 8-15 kts with some gusts in the afternoon at 20-25 kts especially from KALB/KPSF south and east. Outlook... Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of RA...SN. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: Low Operational Impact. Slight Chance of SHSN. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... The Fire Weather season has officially begun across eastern New York and western New England. Despite this, snow cover is in place across much of the region, which will mitigate any potential fire weather hazards for the time being. Additional snowfall is expected late tonight through Wednesday night which will continue to prevent issues in the near future as well. High pressure over southern Canada will continue to allow for cold temperatures today with a mostly sunny sky. A storm system organizing over the mid-Atlantic region will move off the eastern seaboard for tonight through Wednesday night, allowing for a moderate to heavy snow for areas south and east of the Capital Region. Behind this storm, dry and cold weather will continue for the remainder of the week. && .HYDROLOGY... No hydrologic issues are anticipated through the week. Dry weather will continue through the remainder of the week for areas north and west of the Capital Region. Meanwhile, southern and eastern areas will see some snow between late tonight and Wednesday night, with the heaviest amounts across Dutchess, Litchfield counties. Total liquid equivalent in these areas will approach up to an inch. Dry weather is then expected behind this storm for the remainder of the week and into the weekend. This snowfall won`t have any immediate impact on area rivers and streams. A slow diurnal snowmelt is expected over the next several days, with temperatures above freezing during the day, and below freezing at night. There will be little impact on the waterways with minimal, if any, rises. 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. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday for CTZ001-013. NY...Winter Weather Advisory from 8 AM Wednesday to 8 AM EDT Thursday for NYZ061-063-064. Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday for NYZ065-066. MA...Winter Weather Advisory from 8 AM Wednesday to 8 AM EDT Thursday for MAZ025. VT...None. && $$ SYNOPSIS...JVM/Wasula NEAR TERM...Wasula SHORT TERM...MSE LONG TERM...Wasula AVIATION...Wasula FIRE WEATHER...Frugis/JVM HYDROLOGY...Frugis/JVM is the U.S. government's official web portal to all federal, state and local government web resources and services.