Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 310839 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 439 AM EDT Sun May 31 2020 .SYNOPSIS... Much cooler and drier air will infiltrate the region today and tomorrow with temperatures averaging about 10 degrees below normal. A few showers are possible tomorrow, mainly north of Interstate 90. Then, temperatures slowly return to normal by the middle of the week as chances for more widespread showers also returns to the forecast. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 3:30 AM EDT, latest GOES16 water vapor imagery shows our upper level trough continuing to push into the Northeast. With low and mid-level channels capturing the abundant dry air and surface observations showing dew points falling into the 40s, it`s no wonder that skies have remain mostly clear overnight. The one exception remains the southern Adirondacks where the nighttime fog channel shows stubborn low stratus lingering. The combination of mainly clear skies and low dew points within the cold air advection regime, has allowed temperatures overnight to drop into the 50s with low to mid 40s in the hill towns and higher terrain. However, temperatures have not cooled to their respective dew points and we do not have any concerns of frost due to breezy west to northwest winds. Still, it will be a chilly Sunday morning with morning lows in the 40s and 50s. As the parent trough moves overhead today, its associated cold pool will influence our sensible weather. 850hPa isotherms will only range -0.5C to +1.5C which is 2 to 3 standard deviations below normal, as per the 00UTC GEFS. As high pressure centered over the Upper Great Plains noses eastward, a tightening pressure gradient over the Northeast will yield breezy northwest winds today reaching 8 to 15 with gusts to 20-25mph (strongest down the Mohawk Valley). Thus, high temperatures today will only rise into the low to mid 60s with mid to upper 50s in the hill towns and higher terrain. Our typical high temperature for May 31 is in the mid 70s so today will be roughly 10 degrees cooler than normal and significantly cooler than recent days. Humidity levels will also remain very low as PWATs stay below 0.50". Luckily, we should remain mostly sunny as morning sun should only mix with a few afternoon clouds as we reach our convective temperature. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... Our parent trough will gradually exit into New England tonight and with northwest flow ushering an even cooler Canadian air mass, overnight lows should turn quite chilly by early June standards. Expecting Monday morning lows to range from the mid- 30s to low-40s. However, with one last weak shortwave rotating into the cyclonic flow towards the Northeast and bringing increased mid-level moisture, clouds should increase overnight. This should impede temperatures from becoming as low as they could have and should mitigate frost formation. Thus, we agree with the previous shift in removing any frost mention for the southern Adirondacks and southern Greens. Monday should feature partly sunny skies and below normal temperatures once again, although not as cool as Sunday. Highs should reach into the mid to upper 60s (mid to upper 50s in the hill towns and higher terrain areas). In addition, a few scattered showers are possible Monday afternoon as the aforementioned shortwave rotates into the Northeast with guidance showing a pocket of increased 700hPa RH with it. For now, we only show slight chance POPs given QPF amounts from the global guidance only shows a few hundredths materializing from any showers. The GFS, NAM80 and CMC-NH all show once last area of scattered showers moving into southern VT Monday evening as the main trough becomes negatively tilted and finally exits into the Atlantic. Since the ECMWF remains dry and the latest blended guidance painted a dry forecast, we limited POPs to slight chance into Monday evening for this area. Otherwise, overnight lows should be slightly milder than previous nights due to increased clouds, only falling into the mid to upper 40s. Very broad upper level ridging centered over the country builds eastward on Tuesday. With the Northeast remaining on its westward side, we should be in the northwest flow regime. Guidance shows a few weak shortwaves rounding the periphery of the ridge into the Northeast (the "ring of fire") which should keep clouds in place but should allow temperatures to moderate in the upper 60s to low 70s. A warm front looks to push into the region Tuesday afternoon with a decent temperature gradient analyzed at 700hPa on the latest global guidance. We thus placed widespread chance POPs for the entire region from 18 UTC Tuesday to 12 UTC Wednesday to account for an increased chance of showers. Since the best instability gradient looks to remain over the mid- Atlantic, we did not mention the potential for thunderstorm. However, we will closely monitor trends since this pattern could favor elevated instability rounding rounding the periphery of the ridge into our area. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The extended forecast begins with a short-wave in the west to northwest flow aloft impacting the region for the mid week, but then an increasing trend for fair and tranquil weather for THU into FRI before a cold front may bring some isolated showers to open the weekend. A warming trend is also expected late in the week into the weekend. Wed-Wed Night...In the northwesterly flow aloft, a short-wave will be diving southeast from southeastern Canada across upstate NY and New England with some showers and possibly a few thunderstorms, as the warm and cold fronts move through the region. The region will likely get into a warm sector with sfc dewpts in the 50s to lower 60s. The latest 00Z GFS has MUCAPEs mainly less than 500 J/kg with Showalter Stability Indices of 0C to -2C. Some elevated instability is present. The 00Z ECMWF has the best instability suppressed south and west across PA and the Mid Atlantic Region. Enough synoptic forcing with falling heights and some moisture convergence with the sfc boundaries supports at least high chance PoPs with temps in the mid 70s to lower 80s in the valleys, and mid 60s to lower/mid 70s over the higher terrain. The cold front moves through early Wed night with the threat for showers diminishing. Some weak cold advection occurs in the wake of the front for lows in the 50s to around 60F in the Capital Region south into the Mid Hudson Valley and NW CT. Thursday into Friday...High pressure builds in from the Great Lakes Region on Thursday. A lingering isolated shower is possible on THU especially over the higher terrain, but a mixture of sun and clouds is expected with comfortable humidity levels with sfc dewpts in the 40s to mid 50s. Max temps will be a little above normal with 70s to lower 80s in the valleys, and mid 60s to mid 70s over the higher terrain. Fair and cool weather is possible THU night into early FRI with the sfc anticyclone building in over NY and PA. Lows will be in the upper 40s to mid 50s across the region. The mid and upper level flow begins to flatten and be more zonal late Friday. Another dry day is expected and H850 temps rise to about +13C to +15C based on the 00Z GFS, as sfc temps may get about 5 to 8 degrees above normal with lower 80s in the valleys, and upper 60s to upper 70s over the hills and mtns. Friday night into Saturday...The next short-wave trough moving through the amplifying mid and upper level trough impacts the forecast area Fri night into Saturday. The cold front will approach and move through some time early in the weekend. Temps will open the weekend a little above normal similar to FRI. The drier half of the weekend may end up Sunday, but timing these impulses in northwest flow is tricky and the amount of low-level moisture available is challenging. For now, we have mainly slight chance PoPs heading into Saturday. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... A cold front continues to move east of New England early this morning. Cyclonic flow continues aloft associated with an upper level trough today into tonight. High pressure will be building in at the surface from the Great Lakes Region today. Some post frontal stratus continue this morning for KALB-KPSF northward with a brief period of MVFR stratus at KALB/KPSF 06Z- 09Z/SUN with cigs 2.5-3.0 kft AGL. Dry air aloft will continue to rapidly move into the region causing the skies to clear with few- scattered stratocumulus/cumulus and VFR conditions the duration of the TAF cycle. The skies may become sct-bkn at 5.0-6 kft AGL during the late morning into the afternoon with the diurnal instability cumulus due to the cool air aloft. The skies will clear shortly before daybreak, as the anticyclone ridges in. The winds will be west to northwest at 8-12 kts this morning with a few gusts around 20 kts at KPSF/KALB. The winds will increase from the northwest to north at 10-15 kts with some gusts close to 25 kts at KALB/KPSF due to deeper mixing. The winds will decrease around or shortly before 00Z/MON to less than 10 kts. Outlook... Monday Night: Low Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of SHRA. Tuesday Night: Moderate Operational Impact. Chance of SHRA. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA. Thursday: Low Operational Impact. Slight Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Dry and much cooler conditions are expected today. RH values this afternoon should drop to between 30 to 40 with breezy northwest winds increasing to 8 to 15mph including gusts to 20-25mph (strongest down the Mohawk Valley) in the afternoon. Clouds increase tomorrow with RH values dropping to 30 to 35 percent. Northwest winds stay a bit breezy between 5 and 15mph, gusts to 20mph. Our next chance for more widespread showers looks to arrive Tuesday into Wednesday. && .HYDROLOGY... The weather pattern remains devoid of any appreciable rainfall today and tomorrow but chances for showers increases by the middle of the work week. There remains uncertainty on the coverage and intensity of the next potential rainfall event for Tuesday into Wednesday but at this time, it does not look to be particularly significant. Thus, river levels should remain nearly steady through mid-week. 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...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Speciale NEAR TERM...Speciale SHORT TERM...Speciale LONG TERM...Wasula AVIATION...Wasula FIRE WEATHER...Speciale HYDROLOGY...Speciale is the U.S. government's official web portal to all federal, state and local government web resources and services.