Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 260834 AFDALY Area Forecast Discussion National Weather Service Albany NY 434 AM EDT Mon Jun 26 2017 .SYNOPSIS...
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An upper level disturbance will move across the region today with mainly isolated to scattered showers and thunderstorms in the afternoon into the early evening. An upper level low and a cold front will bring another chance of showers and thunderstorms on Tuesday with cooler than normal temperatures. High pressure will build in from the Mid Atlantic Region by Wednesday, but temperatures will still run slightly below normal for late June.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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As of 434 AM EDT...An mean long-wave trough over southeast Canada and the eastern CONUS will continue to impact the forecast area the next several days. A series of short-waves moving through the upper level trough will keep a threat of isolated-scattered thunderstorms across eastern NY and western New England today into Tuesday. The upper level low continues to dig and amplify upstream over the western and central Great Lakes Region today. The low and mid-level flow will become southwesterly over the region ahead of the next mid-level short-wave. This short-wave is not as strong as yesterdays, but still with a respectable cold pool aloft with H500 temps of -16C to -21C and steepening mid-level lapse rates to 6.5-7C/km coupled with weak to modest instability in the 200-800 J/kg range with slightly higher pockets will allow for isolated to scattered thunderstorms to develop in the afternoon into early evening again according to the latest GFS/NAM. The low-level moisture is a bit sparse with sfc dewpts in the upper 40s to mid 50s, and the 0-6 km bulk shear do not increase to 40-50 kts over the majority of the forecast area until the mid to late pm ahead of the short-wave, when the diurnal heating starts to wane. PWATS will be in the 0.7" to 1.0" range. Most of the CAMs such as the 3-km HRRR and 3-km NAM show a few stronger cells late in the day, but again we are not confident about any isolated severe thunderstorms. Some small sub-severe hail and gusty winds will be possible with a few cells. The instability looks limited along with the low-level moisture for more widespread coverage and a severe threat. We have kept POPS in the chc range in the afternoon with some likely values near the west-central Mohawk Valley and western Adirondacks where some lake moisture will be tapped for a little more coverage. Less coverage in terms of the showers and thunderstorms will be south of the Berkshires, northern Catskills, and Capital Region. H850 temps according to the latest GEFS will be close to 1 to 2 standard deviations cooler than normal. H850 temps fall off to +7C to +11C from northwest to southeast across the forecast area late in the day with short-wave and sfc trough passage. High temps will generally be in the upper 60s to mid 70s over the valleys and across the hills. A few upper 70s are possible in the mid-Hudson Valley. Expect upper 50s to mid 60s over the mountains. Humidity levels will be very comfortable for late June with southwest to west winds of 10-15 mph.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
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Tonight...The short-wave lifts northeast across the forecast area into northern and western New England. The isolated- scattered showers and thunderstorms should diminish quickly between 8-11 pm. The skies will become partly cloudy. Another cool night is expected with lows in the upper 40s to mid 50s across the forecast area. The strong upper level trough and its associated cold pool will be quickly approaching by daybreak TUE. Tue-Tue night...The H500 cold pool moves over the forecast area with H500 temps of -20C to -23C. Low and mid level heights will fall ahead of the upper low, and the differential cyclonic vorticity advection will kick off instability showers and thunderstorms in the late morning into the afternoon. Mid-level lapse rates will remain steep coupled with SBCAPE values in the 250-750 J/kg range due to sfc dewpts in the mid 40s to mid 50s. Wet-bulb zero heights will be in the 6-8 kft AGL range. A strong mid and upper level jet axis will remain over the region. Some small hail mainly penny size or smaller will be possible as well as gusty winds, as the the cold front and upper level trough axis moves across the region. High temps will run about 5-10 degrees below normal with upper 60s to lower 70s common in the valley areas, with some mid and upper 70s in the mid-Hudson Valley and NW CT. Upper 50s to mid 60s will be likely across the hills/mtns. The showers and thunderstorms decrease in coverage overnight with the loss of the diurnal heating, as lows will be in the upper 40s to lower 50s under the cool upper low. In the H850 cold advection temps will fall back to +6C to +10C. Wed-Wed night...The residual cold pool and a weak impulse in the northwest flow associated with the upper low will still focus a few showers and thunderstorms especially north and east of the Mohawk Valley and Capital Region during the day. High pressure will be attempting to ridge in from the Mid Atlantic Region. This day should not be a washout, and could end mostly dry for the southern half or two thirds of the fcst area. High temps will still run about 5 degrees or so below normal for late June. Weak low and mid level ridging continues to be over the region Wed night, but a warm front and a possible MCS may approach from the Great Lakes Region for THU. Lows will be mainly in the 50s with increasing mid and high clouds towards daybreak.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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After a stretch with cool temperatures and low humidity levels, the long term period will feature rising temperatures and humidity along with chances for showers and thunderstorms each day. A cyclone is forecast to track eastward across the upper Great Lakes on Thursday. A warm front associated with this system should move across our area, bringing showers and some thunderstorms. The best likelihood looks to be from around I-90 northward, but at least scattered coverage expected even farther south. Much of the instability will be elevated on Thursday, so stronger storms are not anticipated. Humidity will noticeably increase by late in the day, with late day high temperatures getting back to near normal. Models still indicating potential for showers and a few storms Thursday evening, but coverage should decrease by around late evening. Thursday night will be the first of a string of warm/muggy nights through the upcoming weekend, with low temps mainly in the 60s. Despite the lack of any significant cyclones and/or boundaries around on Friday, there could still be scattered showers and thunderstorms around due to zonal flow aloft with embedded disturbances moving through. With warm temps and dewpoints in the mid to upper 60s, it will not take much heating/forcing to produce diurnally driven scattered convection. Saturday looks to be a potentially active convective day and will have to be watched for strong to severe thunderstorms. A cyclone is forecast to track near or north of the St. Lawrence river valley, with a pre-frontal trough moving through our area during peak heating time. Moderate to high instability may develop given sufficient heating. It will remain humid, so gusty winds and locally heavy rainfall could occur with any storms. Depending on the eventual timing, the actual cold front associated with the Quebec cyclone may result in additional showers and thunderstorms on Sunday. While there is at least a chance of showers and/or thunderstorms in virtually each period of the long term forecast, it will not be raining the entire time. However, it should be stressed that anyone with outdoor plans should stay informed and be alert for the potential for thunderstorms.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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Showers have pretty much diminished across the area, although there still are a few light showers just west of KPSF so will indicate a VCSH in the TAF there for the next few hours. Otherwise, looking at the fog potential overnight, there is some persistent light flow at the surface which should preclude fog formation for at least the next couple hours, along with a deck of mid level clouds moving into KPSF. However, winds may go calm towards sunrise especially at KGFL where some fog/low stratus cloud development is possible. Will mention a TEMPO for MVFR conditions at KGFL from 08Z-10Z, but some brief IFR will also be possible. Fog not expected at other sites, but cannot be completely ruled out. Will keep an eye on trends for possible amendments. Then scattered showers and thunderstorms are expected to develop this afternoon as an upper level trough approaches from the west, mainly affecting the KGFL/KALB/KPSF terminals. Will mention PROB30 groups for now. Brief gusty winds and MVFR/IFR conditions will be possible with any showers/storms. Winds will be west-southwest around 5 kt or less through much of the morning, increasing to around 5-10 kt by this afternoon. Outlook... Tuesday Night: Slight Chance of SHRA...TSRA. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday Night: High Operational Impact. Likely SHRA...TSRA. Friday: Moderate Operational Impact. Chance of SHRA...TSRA. Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.
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&& .FIRE WEATHER...
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An upper level disturbance will move across the region today with mainly isolated to scattered showers and thunderstorms in the afternoon into the early evening. An upper level low and a cold front will bring another chance of showers and thunderstorms on Tuesday with cooler than normal temperatures. High pressure may bring dry weather from the Capital Region south on Wednesday. The RH values will lower to 35 to 65 percent across the region today with the lower values across the Mid-Hudson Valley and northwest Connecticut. Expect a near full recovery in the RH values Tuesday morning in the 85 to 100 percent range and the minimum RH values in the afternoon will be in the 35 to 60 percent range. The winds will from the southwest to west at 5 to 15 mph today, and 5 to 10 mph tonight. The winds will increase from the southwest to northwest at 10 to 15 mph Tuesday with some gusts in the 20 to 25 mph range.
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&& .HYDROLOGY...
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No widespread hydrological problems are anticipated over the next several days. Scattered showers and isolated to scattered thunderstorms are expected today through Tuesday, mainly during the afternoon and evening hours, as a series of disturbances impact the region with an upper low. Basin average rainfall amounts will generally be a tenth to a quarter of an inch in some locations. A brief period of mainly dry weather is expected most of Wednesday into Wednesday night with ridging from the south. An active pattern sets up Thursday into the weekend with showers and thunderstorms possible with increasing humidity levels. Rainfall amounts will vary based on where any convection occurs. The most widespread potential rainfall is expected Thursday and Saturday. 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.
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&& .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...Wasula SHORT TERM...Wasula LONG TERM...JPV AVIATION...JPV FIRE WEATHER...Wasula HYDROLOGY...BGM/Wasula

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