Wellsville, NY Weather

What Has Changed

No major changes with this forecast update.

Key Messages

1) Primarily dry weather is expected through this weekend, but periodic rain showers are possible this Thursday evening through Thursday night and again this Sunday. Near-record warmth is forecast this Thursday.

Discussion

KEY MESSAGE 1...Primarily dry weather is expected through this weekend, but periodic rain showers are possible this Thursday evening through Thursday night and again this Sunday. Near-record warmth is forecast this Thursday.

A surface ridge continues to affect our region today through tonight as the embedded high pressure center moves SE'ward from northern ON toward northern New England, while the ridge aloft builds from the Upper Midwest to the eastern Great Lakes. Dry weather is expected as stabilizing subsidence accompanies the ridge. Widespread low-level clouds, which appear to be associated with moist isentropic ascent ahead of a 925-700 mb shortwave trough axis oriented generally from west to east and embedded in NW'erly mean flow in that atmospheric layer, should exit our CWA generally from north to south by daybreak this morning. Sufficient cloud breaks and weak or calm surface winds should contribute to localized steam fog in the Black River Valley and the inland lake and river valleys of the Western Southern Tier and Finger Lakes Region during the predawn hours through about 10 AM EDT today. However, a sufficiently-cold air mass, NE'erly to ENE'erly mean flow in the surface to 925 mb layer, and weak/shallow lake-induced CAPE profiles amidst limited synoptic-scale low-level moisture over ~14C Lake America should allow scattered and shallow lake-effect stratocumuli to impact portions of Western and Central NY, especially metro Rochester and the northern Finger Lakes Region, through mid-morning. Any lake-effect clouds should dissipate by midday as lake-induced CAPE dissipates via low-level dry air advection and a lowering subsidence inversion.

Lows are still expected to reach mainly the 20's to mid 30's around daybreak this morning and be followed by highs in the mid 40's to lower 60's late this afternoon as low-level CAA persists behind yesterday's cold front passage. Weak or calm surface winds, low humidity, and sufficient cloud breaks, especially farther east, are expected to permit appreciable radiational cooling very late this afternoon through daybreak Wednesday. Lows should reach mainly the lower 20's to lower 30's in North-Central NY and the lower 30's to lower 40's elsewhere in our CWA around daybreak Wednesday.

On Wednesday through Wednesday night, the ridge at the surface and aloft should exit E'ward and allow a warm front starved of low-level moisture to sweep NE'ward through our region and usher-in a somewhat warmer air mass. Fair weather is expected to persist. Late afternoon highs should reach the 50's to lower 60's in North-Central NY and the upper 50's to upper 60's elsewhere in our CWA. Thereafter, overnight lows should reach the mid 30's to mid 40's in North-Central NY and the lower 40's to lower 50's elsewhere in our CWA around daybreak Thursday.

Mainly W'erly to WNW'erly flow aloft and a series of attendant troughs and ridges at the surface and aloft should affect our region this Thursday through upcoming weekend. Current odds favor primarily dry weather as ridging should affect Western and Central NY during the majority of the time period. However, a weak cold front should sweep E'ward through our region Thursday night. Periodic rain showers should impact Western and Central NY Thursday evening and especially Thursday night, along and ahead of the front, due to moist isentropic ascent ahead of a shortwave trough axis aloft and low-level convergence/ascent along the front coinciding with sufficient low-level moisture. Additional periodic rain showers are possible this Sunday due to moist isentropic ascent preceding another shortwave trough axis aloft. Unusually-mild weather for late October is expected on Thursday through this weekend courtesy of largely zonal flow aloft. For example, near-record warm highs in the upper 60's to mid 70's are expected in many lower elevation locations in our Western NY and Finger Lakes counties this Thursday afternoon, including the Buffalo and Rochester metro areas.

Aviation

A line of low ceilings will continue to drop south across western New York as of 06Z this morning. In the wake of the low ceiling, expect improvement to widespread VFR, as seen in KART, KROC, and KIAG. In the wake of the clouds, there may be sufficient cloud breaks and weak surface winds for localized MVFR or worse conditions due to steam fog developing early this morning across the river and lake valleys.

Low clouds are expected to re-develop along the southern Lake America shoreline this morning. Ceilings may reach MVFR at KROC from 12-15z with VFR continuing elsewhere.

Outlook...

Tuesday Night through Wednesday...Dry weather and mainly VFR expected. Localized fog with MVFR or worse conditions will be possible across the inland river and lake valleys Wednesday morning.

Wednesday night through Saturday...Dry weather and mainly VFR expected. However, periodic rain showers with MVFR are possible Thursday night into Friday morning.