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Albany, NY WFO Forecast Discussion
000 FXUS61 KALY 281715 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 115 PM EDT Mon Sep 28 2020 .SYNOPSIS... An upper level disturbance will bring some isolated to scattered showers and patchy fog this morning to the region. A mild air mass for late September will impact the region into Tuesday, as a cold front will slowly approach during the day. The cold front and a low pressure system will bring a widespread rainfall late Tuesday afternoon into Wednesday. Another low pressure system could bring additional rainfall late Wednesday night through Thursday before cooler air moves back into eastern New York and western New England. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A few showers left north of the Capital Region that will affect those areas through the afternoon. Clouds are slowly breaking up over eastern NY and western New England and the greater frequency of breaks in the clouds will help temperatures reach the mid 70s in many areas around 70 to lower 70s north and near 80 south. South to southeast winds will be steady and occasionally breezy as well. Many areas may trend to mostly clear by this evening and the showers north of the Capital Region should shift mainly to northern NY and northern VT by this evening.. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... Tonight...Partly cloudy conditions begin the period, but with abundant low-level moisture we are expecting some low stratus to reform ahead of the cold front slowly approaching from the west. Some patchy fog is also possible, but with a persistent southerly breeze this may prevent widespread fog formation in many areas. We tried to keep it patchy. It will be a muggy night. Mid and upper level heights will continue to fall upstream over the Great Lakes Region, and OH Valley, as a deep mid and upper level trough approaches. A fetch of moisture will commence out of the Gulf of Mexico. A strong upper level jet will set up along the east side of the mid and upper level trough. We should seem some showers start to move into locations in the western Adirondacks and western Mohawk Valley shortly before sunrise from a prefrontal disturbance. Also, the moist southerly flow may allow for some isolated showers or patchy drizzle further east. However, the front with better dynamics does not look to arrive until late TUE pm into WED. It will be a muggy night with lows in the upper 50s to mid 60s. Tuesday...It has been a few weeks, but the forecast area looks to finally get a widespread rainfall over the next 12 to 24+ hours. Deep meridional flow continues over the region with water vapor transport out of the Gulf of Mexico. Multiple short-waves in the southwest flow ahead of the front will impact the region. PWATS increase to +1 to +3 STDEVs above normal based on the latest 00Z GEFS. A south to southwest H850 LLJ increases to 30-40+ kts. The u-wind anomalies will also be +2 to +3 STDEVs above normal. The moist air mass will be tapped into for periods of moderate to locally heavy showers to break out from west to east across the region on TUE. There are still some timing differences with the guidance. Locations from the Berkshires/Capital Region and eastern Catskills have the greatest chance for showers prior to nightfall. A few thunderstorms are also possible with pockets of elevated instability especially over the eastern Catskills/Schoharie Valley. Temps will be mainly in the 60s to lower 70s west of the Hudson River Valley, and lower to mid/upper 70s from the Hudson River Valley eastward, except some upper 60s over the western New England higher terrain. Tuesday Night into Wednesday...A fairly widespread soaking rainfall should encompass the region Tuesday night with the front slowly moving eastward Tuesday night and potentially reaching the eastern New England Coast WED morning. The mid and upper level flow will run parallel to the sfc front. PWATS will continue to run above normal by +1 to +3 STDEVs TUE night in the 1.25"-1.75". Good moisture convergence will occur ahead of the front and with a weak wave moving along it. There are small pockets of instability (mainly elevated) with Showalter indices 0 to -2C in the NAM/GFS for parts of the region. A slight chance of thunderstorms was kept in the forecast TUE night across the region. Some locally heavier bursts of rain will be possible. The dry antecedent conditions should preclude any hydro issues. WPC Day 2 ERO continues a Marginal Risk. Gridded FFG values remain very high. The question will be where the front will be located by WED morning. Our current thinking is that it should be moving east of the region by late WED morning and we should see a reduction of the showers from the Hudson River Valley westward by the late pm. Total rainfall from the initial front and wave will generally be in the 1 to 2 inch range, but there continues to be variability in the guidance on the placement of the axis of rainfall. A few locations across the Litchfield Hills, as well as the eastern Catskills and southern Adirondacks could have amounts closer to 3" due to the south/southeast flow orographically enhancing the rainfall. Expect lows to fall back to the 50s to lower 60s with a few upper 40s over the southern Adirondacks. Highs on WED will be in the mid 50s to lower/mid 60s over the higher terrain, and generally mid 60s to around 70F in the lower elevations. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... One final area of low pressure will track along a nearly stationary front Wednesday night. This low is projected to be located in the eastern NC/VA area Wednesday evening and then track northeastward across New England through Thursday morning. There remain slight model differences regarding the track of this low and how large the precipitation shield will be. Have placed the greatest pops across western New England (closer to the projected front and track of the low) with lower pops farther west into Herkimer County. This system could contain some much-needed moderate to heavy rainfall with the greatest amounts across western New England. Will continue to monitor trends over the coming days. In the wake of this system, another weaker low across Quebec will send a cold front across the region later Thursday into Friday, bringing a cooler air mass for the remainder of the period. With 850 hPa temperatures falling below 5C, there will be enough low-level moisture and a temperature difference with Lake Ontario for lake- effect/enhanced showers Friday into Saturday. Locations north and west of the Capital District will be most favored for this activity given the projected west to southwesterly mid-level flow over the lake. Additional instability-driven showers cannot be ruled out either due to the strong upper-level support and cold air aloft. Another weak area of low pressure may form just off the Northeast coast later Friday into Saturday, but confidence on whether it develops remains low. High pressure will work into the region on Sunday, gradually bringing an end to any shower activity. Temperatures will trend downward to below-normal values during the long term period, with highs going from the mid-50s to upper 60s to near 70 on Thursday to the upper 40s to lower 60s over the weekend. Lows will start in the mid-40s to lower 50s Wednesday and trend downward to the mid-30s to lower 40s by Friday and Saturday night. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... Through 12z/Tue...Isolated showers, patchy drizzle and low-level stratus is causing mainly IFR/MVFR conditions early this morning. These conditions will continue for a few more hours until a gradual return to VFR is anticipated between 14z-18z. A tempo group was included to show this transition. The afternoon hours will feature generally sct stratocu coverage with still the chance for a brief shower. Shower activity will come to an end later Monday afternoon into early Monday evening as clouds partially clear. However, some patchy fog/mist and/or low-level stratus is anticipated to develop overnight. Highest confidence at this time is MVFR stratus, so will only show that in the TAF`s. Winds will be light out of the south to southeast early this morning, increasing to 6-12 kt with gusts to around 20 kt this afternoon. Winds will then decrease to 4-8 kt tonight. Outlook... Tuesday Night: High Operational Impact. Definite SHRA...TSRA. Wednesday: High Operational Impact. Definite SHRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA...RA. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: Moderate Operational Impact. Chance of SHRA. Friday Night: Low Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... An upper level disturbance will bring some isolated to scattered showers and patchy fog this morning to the region. A warm and humid air mass for late September will impact the region into Tuesday, as a cold front will slowly approach during the day. The cold front and a low pressure system will bring a widespread rainfall late Tuesday afternoon into Wednesday. More unsettled weather is likely Wednesday night into Thursday. Minimum RH values are expected to only be 55 to 70 percent this afternoon, as a warm and humid air mass remains in place. Max RH values will be around 100 percent Tuesday morning, and will only lower to 60 to 85 percent with rain moving in Tuesday afternoon. The winds will be southerly today at 10 to 20 mph, decreasing to around 5 to 10 mph tonight. The winds will be south to southwest at 10 to 15 mph on Tuesday. A widespread rainfall is expected Tuesday into Wednesday. && .HYDROLOGY... Some isolated to scattered light showers will continue today into tonight with amounts of a few hundredths to a tenth of an inch a few spots. A more appreciable and widespread rainfall is then expected Tuesday into Wednesday, as a slow-moving cold front moves across the region. There remains some uncertainty with regards to placement or timing of maximum rainfall amounts, although it does appear increasingly likely for a storm total of 1-2 inches of rainfall with up to 3 inches in favored higher terrain upslope locations /southern Adirondacks...eastern Catskills and Litchfield Hills/ in southerly flow. Given extremely dry antecedent conditions and low stream flows/river levels, this rainfall is not forecast to result in flooding and will be beneficial. Gridded FFG values remain high. If rainfall rates approach an inch an hour some ponding of water may occur on some roadways. Another area of low pressure tracking northward along the east coast may bring additional rainfall to at least parts of the region Wednesday night into Thursday. An additional half an inch to an inch of rainfall is possible. 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. && .CLIMATE... Here is a look at how much precipitation had occurred so far this month at our climate sites and their annual precipitation and departure. Albany NY: September: 0.50 inches 2020: 24.41 inches (-4.68 inches) Glens Falls NY: September: 0.28 inches 2020: 24.35 inches (-4.48 inches) Poughkeepsie NY: September: 0.77 inches 2020: 20.61 inches (-13.98 inches) Bennington VT: September: 2.08 inches 2020: 25.36 inches (-5.34 inches) Pittsfield MA: September: 0.97 inches 2020: 23.73 inches (-9.49nches) && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...NAS SHORT TERM...Wasula LONG TERM...Rathbun AVIATION...Speciale FIRE WEATHER...Wasula HYDROLOGY...JPV/Wasula CLIMATE...