Key messages
- 1) Periods of rain and gusty winds through this evening.
- 2) Much colder tonight through Saturday night with a few wet
What Has Changed
Minor changes to the forecast with this update.
Key Messages
snowflakes possible early Saturday morning.
3) An extended period of dry and warmer weather begins Sunday and lasts most of next week.
Discussion
KEY MESSAGE 1...Periods of rain and gusty winds through this evening.
A sharp mid level trough will advance east across the Great Lakes today through tonight. An associated surface low will steadily deepen through the period as it moves through southern Ontario province today, then northeast down the Saint Lawrence Valley tonight to the Canadian Maritimes Saturday. This system has captured a plume of deep moisture, with PWAT values briefly rising to around 1.75" in the warm sector this morning.
A period of strong isentropic upglide and moisture transport will move northeast across the eastern Great Lakes early this morning as a warm front races northeast across the area. Ascent across the warm front will be enhanced by a 55+ knot low level jet, and continue to support a few periods of rain. The cold front will quickly follow, moving southeast across the area this afternoon and bringing another period of low level convergence and additional showers. DPVA ahead of the mid level trough and strong right entrance region jet dynamics will lag behind the passage of the cold front, allowing for periods of light rain to continue this afternoon and evening even after the surface cold front passes by.
Elevated instability may support a few isolated weak thunderstorms this morning. A few more scattered thunderstorms may develop along the cold front late morning through early afternoon from the Southern Tier into the Finger Lakes along the advancing cold front as modest surface based instability develops. If these storms materialize they may produce gusty winds, with a better risk of severe thunderstorms well southeast of our area where greater instability will develop.
Rainfall amounts will vary widely across the area, generally ranging from 0.25" to 1.0". Terrain will play an important role given the strong boundary layer flow, with downslope areas of the Lake Erie shore and Genesee Valley likely on the low end of the range, while higher terrain is more likely to be on the higher end of the range from upslope enhancement. There may be a few small areas that exceed 1.0" if embedded convection develops.
Finally, it will be quite windy today as a strong 55+ knot low level jet propagates across the eastern Great Lakes. A brief window of downslope winds will continue early this morning along the Lake Erie shore, and later this morning north of the Tug Hill Plateau. The setup for downslope winds is not ideal, with a weak inversion and SSW flow not directly perpendicular to the terrain barriers. Given the marginal setup, expect wind gusts of up to 40 mph in downslope areas this morning, and 25 to 35 mph elsewhere. A brief period of stronger winds will also develop northeast of Lake Erie late morning through mid afternoon as the cold front crosses the area. Once again this setup it not ideal, with most of the strong winds aloft in the warm sector where lapse rates are poor. Boundary layer winds will quickly drop off later this afternoon following the cold frontal passage when lapse rates steepen. Expect peak gusts of up to 40 mph northeast of Lake Erie today.
KEY MESSAGE 2...Much colder tonight through Saturday night with a few wet snowflakes possible early Saturday morning.
Strong cold advection will develop tonight in the wake of the departing low, with 850 mb temperatures dropping into the -5C to -8C range by Saturday morning. The cold air aloft will support increasing lake induced instability overnight with a brief lake response, but short NNW fetch and a rapidly drying synoptic scale airmass will keep lake effect muted and brief. Lake effect and upslope rain showers will develop southeast of the lakes tonight, with a few wet snowflakes possibly mixing in very late tonight through early Saturday morning before the lake effect showers quickly end by late morning. The best chance of a few snowflakes will be across higher terrain, but no accumulation is expected.
The coldest airmass of the fall season so far will arrive for Saturday, with highs only in the 40s areawide, and even upper 30s across the highest terrain despite some afternoon sunshine. Temperatures will drop back into the lower 30s on the lake plains and 20s well inland Saturday night, with frost/freeze conditions likely.
KEY MESSAGE 3...An extended period of dry and warmer weather begins Sunday and lasts most of next week.
High pressure will drift from the Ohio Valley to southern New England Sunday, with southwesterly return flow quickly removing the brief shot of colder air. Temperatures will rebound into the 55 to 60 degree range by afternoon following the cold start.
A strong ridge surface and aloft will then take up residence early next week across much of the central and eastern CONUS, while a slow moving cutoff low remains parked off the Carolina coast much of the week. This pattern will support dry weather most, or even all of next week with abundant sunshine and temperatures a little above average.
Aviation /10Z Friday Through Tuesday/
Low pressure will move through southern Ontario province today, supporting periods of rain and gusty winds. A warm front will race northeast cross the eastern Great Lakes this morning, followed by a cold front this afternoon with each supporting periods of light to moderate rain. Areas of moderate rain will bring some reduction in VSBY, with CIGS generally running MVFR for lower elevations and IFR across higher terrain and the North Country today. Weak instability may support a few isolated thunderstorms as well, especially across the Southern Tier and Finger Lakes this morning through early afternoon.
Gusty SSW winds will continue this morning, then steadily veer to the west and northwest today with the approach and passage of the cold front. Gusts will run in the 20 to 30 knot range areawide, and up to 35 knots near Lake Erie and on the north slopes of the Tug Hill Plateau.
Tonight, much colder air will pour into the eastern Great Lakes. Strong lake induced instability will develop with cold air aloft, although a rapidly drying airmass will keep the lake response muted and brief. Lake effect clouds will produce areas of MVFR CIGS overnight, with scattered showers southeast of the lakes and across higher terrain from lake effect and upslope. It will become cold enough to allow some wet snowflakes to mix in very late tonight, mainly across higher terrain.
Outlook...
Saturday...Areas of MVFR CIGS and scattered rain/wet snow showers early, improving to VFR.
Saturday night through Tuesday...VFR.
Marine
Steadily deepening low pressure will pass just north of the lower Great Lakes today, then move down the Saint Lawrence Valley tonight to the Canadian Maritimes Saturday. A trailing cold front will cross the lakes today, with southerly winds this morning quickly veering to the west and northwest this afternoon with the approach and passage of the cold front.
Sustained winds will increase into the 20 to 30 knot range (with higher gusts) on both lakes today and remain elevated through Saturday morning before quickly diminishing Saturday afternoon as the pressure gradient relaxes. High end Small Craft Advisory conditions will continue through Saturday morning on both lakes.
Buf Watches/Warnings/Advisories
NY...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020. Small Craft Advisory until 11 AM EDT Saturday for LEZ040- 041. Small Craft Advisory until 10 AM EDT Saturday for LOZ030. Small Craft Advisory until 11 AM EDT Saturday for LOZ042. Small Craft Advisory until 2 PM EDT Saturday for LOZ043- 044. Small Craft Advisory until 2 PM EDT Saturday for LOZ045.
DISCUSSION...Hitchcock AVIATION...Hitchcock MARINE...Hitchcock