Pownal, VT 05261 Weather

What Has Changed

Lowered dewpoints/RH values the rest of the afternoon based on observations, due to the mixing with the north/northwest winds due to the sfc pressure gradient between the weak sfc cold front and Subtropical Storm Josephine.

Min temps were lowered Fri and Sat nights blending in colder MAV/MET guidance with NBM. Also lowered dewpoints below NBM Fri/Sat with sfc high building in overhead.

Key Messages

1) High confidence in dry conditions persisting through at least the middle of next week.

Discussion

KEY MESSAGE 1... A weak cold front continues to approach from western and northern NY with some clouds over the North Country and Adirondacks this afternoon. A sfc pressure gradient between the cold front and the mid-level short-wave to the west/northwest and Subtropical Storm Josephine moving northeast into the Atlantic has allowed for north/northwest winds 5-15 mph with some gusts 20-25 mph especially south and east of the Capital Region. The winds will gradually diminish tonight, as the sfc cold front washes out. Light north/northwest winds may persist after midnight from the Capital Region south and east, as the sfc high builds in from southeast Ontario and southern Quebec. With the weak low-level cold advection lows fall back into the 30s with some upper 20s over the higher terrain.

A strong sfc anticyclone builds in over eastern NY and western New England tomorrow, and lasts through the weekend. The strong subsidence from the ridge will yield mostly sunny conditions. PWATs will run 1-2 STDEVs below normal in the dry air mass. Shallow mixing heights and weak cold advection will yield slightly below normal temps with highs in the upper 40s to mid and spotty upper 50s for Fri. The sfc high over southern Quebec, NY and New England will yield ideal radiational cooling conditions with mostly clear skies, light to calm winds with lows in the 20s with a few upper teens over the southern Dacks Fri night. We went below the NBM guidance for lows going closer to the MAV/MET guidance. High pressure remains dominate for the weekend with temps modifying to seasonal to slightly above normal temps with light winds. Ideal radiational cooling is expected again Sat night with chilly temps. The mid and upper level heights begin to fall Sun night into Mon as the the flow aloft becomes more zonal which will allow temps to run near to slight above normal. The next chance of rainfall looks like potentially Wed into Thu with a short-wave and a warm front, but precipitation looks light in the medium range/ensemble/NBM guidance.

Aviation

Through 18z Friday...Flying conditions are VFR at all terminals as of 1:20 PM, and are expected to remain VFR at all terminals through at least 18z Friday. A few mid and high clouds are possible late this afternoon and tonight with/behind a weak cold front, but otherwise skies remain mainly clear. N/NE winds this afternoon will be at 5-10 kt with some gusts to 15-25 kt (strongest at POU/PSF). Gusts diminish by shortly after sunset, but winds remain elevated at 5-10 kt from the N/NE from this evening through 18z Friday. Gusty winds at POU/PSF may lead to some low-level turbulence this afternoon. Have added LLWS at POU/PSF tonight as winds at 2000 ft increase to 35-40 kt from the NE. Slightly weaker 30-35 kt winds from the N/NE expected at 2000 ft at ALB/GFL, so these terminals should fall just short of LLWS criteria.

Outlook...

Friday Night to Tuesday: No Operational Impact. NO SIG WX.