textproduct: Binghamton

WHAT HAS CHANGED

Added in some chances for isolated to scattered pop up showers this afternoon across the western Finger Lakes, Southern Tier and portions of Northeast PA as a shortwave disturbance swings through the area. Lowered expected overnight lows tonight into Tuesday morning as model guidance shows an exceptional radiational cooling environment.

KEY MESSAGES

1) Cold air in place today will lead to a widespread frost and freeze event across much of NY and NEPA tonight.

2) Another trough of low pressure moves in Wednesday into Thursday, keeping the cooler weather around, but with rain and clouds, temperatures will likely remain above freezing.

3) A Pattern change late week into the weekend will allow for warmer air to return to the Northeast US.

DISCUSSION

KEY MESSAGE 1...

With the cold air aloft and strong solar heating, self destructive sunshine has resulted in instability with clouds and showers forming across the region. Its fairly dry below the cloud bases and with a subsidence inversion around 500 mb, the depth of the showers is short so precipitation will be light and struggle to reach the surface. Areas that it does rain, will likely see fog formation overnight with skies clearing towards dusk with the loss of day time heating.

Tonight looks cold, with an efficient set up for radiational cooling. Clear skies and dry air aloft with high pressure building in at the surface, helping the winds to go calm. Went below model guidance for lows, with most areas getting below freezing outside of the Wyoming Valley and the lower elevations of the Finger Lakes. The coldest temperatures will be in some of the higher elevated valleys in the Catskills and in Steuben County where lows may dip into the mid to low 20s.

KEY MESSAGE 2...

Brief ridging builds in Tuesday into Wednesday with flow aloft becoming Southwesterly, bringing in warmer air ahead of another trough digging into the Great Lakes region. This trough wont have a lot of moisture to work with initially as flow from the gulf is still cut off. Precipitable water values rise to around 0.5 to 0.8 inches which is just a little above climatology for mid May. The speed of the trough has slowed some so the unsettled weather it will bring will last more into Thursday night and potentially into early Friday morning. With the lack of deep moisture but good lift, most areas will get between a quarter and a half inch of rain between Wednesday night and Friday morning which is not enough to cause any issues. A few spots in the Catskills may get near an inch of rain as some Atlantic moisture wraps around the low and upslopes into the mountains Thursday into Thursday night. With 850 mb temperatures above freezing, precipitation with this trough is expected to be all rain.

KEY MESSAGE 3...

Once this trough is through late Friday or Friday night 500 mb heights slowly rise and 850 mb temperatures climb back towards +10C over the weekend. Zonal flow sets up aloft with southerly flow from the gulf through the central US could mean the pattern will remain active with frequent chances of showers and thunderstorms. At least day time highs will be back into the 70s and lows in the upper 40s and 50s. Looking beyond this into early next week, there are hints that the pattern could completely flip with ensembles showing greater odds of Western US troughing and east coast ridging in the 8 to 14 day period. This could mean daytime highs pushing into the 80s for portions of Central NY and Northeast PA next Monday and/or Tuesday.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR with light winds throughout the TAF period.

Outlook:

Tuesday afternoon thru Tuesday evening...VFR conditions expected.

Late Tuesday night through Thursday...Showers likely with associated restrictions as low pressure pivots into the region.

Thursday night and Friday: Slow lifting and clearing of restrictions toward VFR. Timing still somewhat uncertain.

Friday night and Saturday: Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Freeze Warning from midnight tonight to 9 AM EDT Tuesday for PAZ038>040. Frost Advisory from midnight tonight to 9 AM EDT Tuesday for PAZ043-044-047-048-072. NY...Freeze Warning from midnight tonight to 9 AM EDT Tuesday for NYZ009-022>025-036-037-044>046-055>057-062. Frost Advisory from midnight tonight to 9 AM EDT Tuesday for NYZ015>018.