textproduct: Binghamton

WHAT HAS CHANGED

A Frost Advisory has been issued for tonight across Yates, Seneca, S Cayuga and Onondaga counties in NY and Luzerne and Lackawanna counties in PA as the growing season in these counties starts on May 1. Most of the forecast remains on track outside of lowering dewpoints and increasing winds Sunday afternoon.

KEY MESSAGES

1) Scattered rain showers and drizzle will move across the region through the evening, especially across the Finger Lakes and Twin Tiers regions. High pressure builds in tonight with clearing skies and light winds allowing frost to develop across the area.

2) A cool airmass will remain across the region through the weekend with scattered rain showers expected Friday and Saturday. Snow may mix in across higher elevations starting Friday evening/night. Temperatures will fall into the low to mid 30s thru Sunday, allowing for continued frost/freeze chances in our growing zones.

DISCUSSION

KEY MESSAGE 1...

Patchy drizzle remains across portions the area this afternoon. A line of rain showers and drizzle is moving in from the west, and if the showers can hold together, rain and drizzle should fall across portions of the Finger Lakes, Twin Tiers and Wyoming Valley late this afternoon and evening.

Conditions will dry out by mid to late evening as high pressure builds in from the WSW. NW flow from the incoming high will push a cold airmass into the region from Canada, and combined with clearing skies and light to calm winds, temperatures are expected to fall into the low to mid 30s. The growing season starts in the Finger Lakes region and the Wyoming Valley tonight, and with forecast conditions showing frost potential, a Frost Advisory has been issued for Yates, Seneca, S Cayuga and Onondaga counties in NY and Lackawanna and Luzerne counties in PA. Frost will probably occur outside these counties as well, but the growing season does not start until May 11 for the rest of our CWA. The Frost Advisory will be in effect from 11pm this evening to 9am Friday.

KEY MESSAGE 2...

An upper level low spinning between the Great Lakes and Hudson Bay will be the main weather driver for the weekend. The broad trough sitting overhead will keep temperatures about 10 degrees cooler than normal for this time of year. A shortwave will move through the area Friday, developing a weak surface low south of the Great Lakes that will track to the east. This low will bring scattered rain showers to the area Friday afternoon into the overnight hours. 850mb temps in the -3C to -4C range during the evening and overnight hours will allow for snow to mix in across higher elevations where precipitation remains. Lows Sat and Sun night will be cold once again, with low to mid 30s expected. Sunday night looks to be the coldest, with widespread temps near freezing as we should see radiational cooling under high pressure. Frost advisories or even a freeze warning might be needed, especially if skies can clear out and winds become light enough.

Southerly flow will return Monday, pushing temperatures back into the 60s. Tuesday will be warmer with upper 60s to mid 70s forecast. Unfortunately, rain is expected to return with these warm temperatures as a strong trough and associated cold front will move into the area mid-week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Clouds will decrease this evening with light winds. While not currently expected, some patchy fog is possible at KELM in the typical 06-12Z window. Increasing clouds and a few rain showers later in the afternoon may be sufficient for some MVFR restrictions. Highest chances by 00Z Saturday are at KELM, KITH and KSYR.

Outlook:

Friday night: Some MVFR restrictions with showers in the evening. Saturday through Monday... Mainly VFR, but restrictions will be possible at times in isolated to scattered showers.

Tuesday...Widespread showers and associated restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Frost Advisory from 11 PM this evening to 9 AM EDT Friday for PAZ044-047. NY...Frost Advisory from 11 PM this evening to 9 AM EDT Friday for NYZ015>018.