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Albany, NY WFO Forecast Discussion
000 FXUS61 KALY 271049 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 649 AM EDT Mon May 27 2019 .SYNOPSIS... High pressure will build in from southeast Ontario over the region today with partly to mostly sunny conditions mainly dry weather with seasonable temperatures. Clouds will increase tonight with the surface high moving eastward across New England, and a warm front approaching from the south. Periods of rainfall will occur ahead of the warm front with weak disturbances moving along it Tuesday into Tuesday night. A brief period of dry weather may occur Wednesday before another low pressure system moving along the front brings showers and isolated thunderstorms once again late Wednesday into Thursday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 649 AM EDT...A weak secondary cold front is approaching northern NY and Lake Ontario associated with the upper trough axis. The skies have cleared, but some clouds may increase in the late morning with this feature. The 3-km NAMnest/GFS/ECMWF has a few showers in the N to NW flow pop-up south of Lake Champlain and the northern Adirondacks and drift southward into the eastern Adirondacks/Lake George Saratoga Region. We increased the cloud cover slightly this afternoon north of the Capital Region and did add the isolated threat of a brief shower or sprinkle in these areas. It should be partly to mostly sunny most of the day with the sfc anticyclone building in from the northern/eastern Great Lakes Region, and southeast Ontario over NY and New England by the afternoon. H850 temps lower to +6C to about +10C across the region from north to south in the cold advection in the wake of the front yesterday. H925 temps will be in the +13C to +17C range with decent mixing and sunshine, we expect max temps this Memorial Day to be near or slightly above normal and closer to the warmer MAV MOS values with highs in the lower to mid 70s in many of the valley locations with some upper 70s in the mid Hudson Valley and NW CT. Expect 60s to lower 70s over the hills and the mtns. A few upper 50s are possible over the high peaks of the southern Greens and Adirondacks. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... Tonight...High clouds will be on the increase from the south and west, as the sfc high moves eastward across New England, and then offshore. Partly cloudy to mostly clear skies with light to calm winds early on will allow for some radiational cooling in the dry air mass. Some patchy frost is possible over the southern Adirondacks (mostly northern Hamilton Co.) and the southern Greens where some mid and upper 30s are possible. The rest of the forecast area will be in the 40s to lower 50s. The clouds will thicken and lower, as the warm front approaches from the lower Great Lakes Region and west-central PA. Some light rain may quickly move in west of the Hudson River Valley before daybreak. Tue-Tue Night...The mid and upper level flow becomes flat and near zonal over the Northeast. A low-level baroclinic zone sets-up between the retreating high and a wave moving in from the Great Lakes Region toward upstate NY. The low-level jet strengthens with a brief H850 +v-wind /southerly/ anomaly of 1-2+ STD DEVs above normal impacting the region TUE pm into TUE night. PWATs increase +1 to +2 STD DEVs above normal based on the 00Z GEFS. A cool stratiform rain is likely with isentropic lift ahead of the front and wave. It will be a chilly afternoon with temps struggling to get out of the 50s with some mid and upper 40s over the northern mtns. A few lower 60s are possible over the mid-Hudson Valley if locations south of Albany get briefly in the warm sector. A very strong low-level inversion is in place, but the latest NAM does indicate some decent elevated instability from the Mohawk Valley/Capital Region south during the afternoon into the early evening. The 00Z GFS is surpressed further south. The 00Z NAM has MUCAPEs increase to 500-1000+ J/kg over the eastern Catskills, Mid Hudson Valley and portions of SW New England. The low-level air mass looks fairly stable, but there is enough elevated instability with decent deep layer shear for isolated to scattered thunderstorms from the I-90 corridor south. SPC`s Day 2 has the Marginal Risk graze the eastern Catskills, Mid-Hudson Valley and NW CT. This threat is conditional the elevated instability is utilized with likely hail the main threat. The 00Z NAM nest indicates a line could get going when the wave or secondary weak impulse moves by. Again, the threat looks minimal with the stable air mass. The likely and categorical PoPs were lowered prior to midnight, as the wave departs and the warm front sags back farther south overnight over PA. Weak high pressure may also build in with lows in the mid 40s to lower 50s. Some patchy fog may also develop. Total rainfall looks to be in the 0.50-1.00" range with any locally higher amounts tied to convection. Wednesday...The flow aloft remains nearly zonal or quasi-zonal. Low-level stratus may linger in the morning, but some subsidence in the wake of the wave or waves may yield a fairly dry day based on the latest 00Z GFS/NAM and to an extent to the 00Z ECMWF. The CMC is the wettest with the next impulse moving along the front. We went with slight chc PoPs for the morning west of the Hudson River Valley, and slight to low chc during the afternoon to stay in sync with the neighboring offices. Isolated thunderstorms were kept in west of the Hudson River Valley. The better synoptic forcing with the warm front and the next wave looks to occur shortly before or just after nightfall. Highs will still be slightly cooler than normal in the 60s to lower 70s for most of the region. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The period starts out Wednesday night with a zonal flow aloft in place across the region. A weak upper level disturbance and associated surface trough could result in mainly scattered showers. Instability appears to be rather minimal at this time, so will just mention slight chance for thunder. The pattern is expected to become slightly more amplified on Thursday, as an upper level trough advances southeast across southern Ontario/Quebec. In the low levels, warming should occur well ahead of a surface cold front which would allow for at least modest de-stabilization. There is uncertainty in terms of the low level moisture, as the boundary layer flow looks to be W-SW and PWAT/moisture flux anomalies are not forecast to be overly impressive. Still, given the expected setup will mention showers becoming likely by early Thursday evening with a chance of thunderstorms. Some of the storms could become strong, but this is highly dependent on the eventual instability. Showers/storms should diminish either by late Thursday night or Friday morning, as the system`s cold front pushes through. There are model differences in the timing, with the ECMWF most progressive, while the GFS is slower. Given the expected upper level pattern will lean towards the more progressive scenario and only mention slight chance pops for Friday. Temperatures look to be near normal, with northwest winds resulting in comfortable humidity levels. Tranquil conditions expected Friday night through Saturday with a weak area of surface high pressure forecast to be in place and a lack of any significant upper level short waves in the vicinity. Dry weather may last into Sunday, although an approaching cold front could result in scattered showers/thunderstorms depending on the timing/placement. Overall, temperatures should continue to be near normal as early June approaches. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... VFR conditions will prevail through the 24 hour TAF period ending 12Z Tuesday, as high pressure builds eastward from SE Canada. Mainly just SCT cumulus clouds will develop later this morning into the afternoon, with bases around 5-6 kft AGL. Coverage may increase enough for BKN cigs at KGFL later this afternoon. High/mid level clouds will increase tonight, as a wave of low pressure approaches from Great Lakes. Any rain should hold off until after 12Z Tuesday. Winds will be north-northwest around 5-10 kt, becoming light and variable tonight. Outlook... Tuesday Night: High Operational Impact. Likely SHRA. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday Night: High Operational Impact. Likely SHRA...TSRA. Friday: Low Operational Impact. Slight Chance of SHRA. && .FIRE WEATHER... High pressure will build in from the northern Great Lakes Region and southeast Ontario over the region today with seasonable temperatures. Clouds will increase tonight with a warm front approaching from the south. The warm front and weak low pressure systems moving along it will bring rain and isolated thunderstorms to the region Tuesday into Tuesday night with more unsettled weather late Wednesday into Thursday. The RH values will lower to 35 to 45 percent this afternoon, and then recover to 85 to 100 percent Tuesday morning. Expect high RH values in the damp air mass on Tuesday with minimum values of 65 to 75 percent. The winds will be north to northwest at 5 to 15 mph this afternoon, and the will be light to calm tonight. Northeast to southeast winds of 5 to 15 mph are likely on Tuesday. A widespread soaking rainfall is likely Tuesday into Tuesday night. && .HYDROLOGY... No widespread hydrological issues are expected on the main stem rivers the next several days. Fair and dry weather is expected today through most of tonight with high pressure in control. A warm front with a few weak waves of low pressure moving along it will bring areal rainfall amounts of a half an inch to about an inch Tuesday and Tuesday night. A brief break in the rainfall is possible early Wednesday. However, the warm front and another low pressure system moving along it will bring rain with some isolated to scattered thunderstorms Wednesday into Thursday with variable rainfall amounts of a tenth to a half an inch, except some locally higher amounts in thunderstorms. The cold front will move through Thursday night. A drier air mass returns Friday into the first half of the weekend. Any elevated within bankfull flows on the main stem river should subside. Please visit our Advanced Hydrologic Prediction Service /AHPS/ web page for specific area rivers and lakes observations and forecasts. && .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...Wasula