textproduct: Binghamton

WHAT HAS CHANGED

Not much was changed from the previous forecast.

KEY MESSAGES

1) A strong cold front will bring widespread showers and embedded thunderstorms later tonight through Tomorrow morning. Isolated strong wind gusts can occur along with locally heavy rainfall.

2) Behind the front it will be breezy and colder, with chances of mixed rain and snow in some parts of the area late Sunday through Tuesday.

3) High pressure and drier weather expected next week with cool mornings and warm afternoons.

DISCUSSION

KEY MESSAGE 1...

Visible satellite shows the marine layer in place holding strong though there has been clearing in the western Southern Tier and Finger Lakes. Western NY and NW PA is destabilizing with all the cumulus that is popping up. The edge of the marine layer will need to be watched for storms that cross into it from the unstable layer as surface winds are backed. This could potentially support brief supercells with hail and wind. For areas east of Elmira, the marine layer will persist with a strong stable layer. Thunderstorms can still move over the stable layer with the warm air advection but with mid level lapse rates only around 6C/km the storms will struggle to develop hail.

Tonight, a cold front comes in, forecast soundings are stable in the low levels so strong winds mixing to the surface are unlikely with the associated line of showers and thunderstorms. The bigger concern is going to be the rainfall on saturated ground. Current mesoanalysis is showing good moisture advection ahead of the front with PWATs near 1.5 inches so rainfall rates could be nearing an inch or two an hour in the stronger cells. Luckily the front will be moving so overall QPF should remain under a half inch but that could be enough to cause some problems especially in smaller drainage basins.

KEY MESSAGE 2...

Temperatures will be falling Sunday into Monday after the strong late season cold front with 850 mb temperatures falling from around 10C early Sunday morning to around -10C by late Sunday evening. Lake effect snow develops in the Finger Lakes and higher elevations of CNY though given the shallow nature of the cold air initially, most of the snow will be light and terrain driven so mainly in the hills.

Monday will have the trough axis swing through with the temperatures cooling through the rest of the atmospheric column. Strong solar heating should help warm surface temperatures despite the cool air aloft so highs will just get into the upper 30s and 40s. Lapse rates in forecast soundings are steep through almost 500 mb with some CAPE likely developing. Thunder was not added to the grids yet but there is a chance that convective afternoon snow/graupel showers could contain lightning.

Monday night into Tuesday, a 500 mb shortwave trough with a weak surface low moves through bringing more widespread snow. Given the timing of the snowfall being overnight, accumulating snow is likely mainly in NY with higher elevations of PA seeing some accumulation as well. QPF is a tenth of an inch or less so snowfall accumulations look to be an inch or less.

KEY MESSAGE 3...

With the long wave trough exiting to the east and high pressure in the SE US, the pattern most of next week looks dry with flow cut off from the gulf until late week. Initially cold NW flow keeps winter like temperatures in the mornings but with strong heating, temperatures quickly modify and warm back to near seasonable norms by mid to late week.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

A warm front will lift north this afternoon, bringing scattered rain showers and isolated thunderstorms. That being said, confidence in seeing thunder at any particular terminal is too low to include in the TAFs at this time.

A cold front pushes through tonight, bringing widespread showers to the area starting after 07z. A marine layer is progged to work its way into the area ahead of the cold front, increasing surface moisture and providing a low level inversion that should trap moisture at the surface, even with the expected gusty winds between 20-30kts. Currently, KRME, KBGM, and KAVP are forecast to have IFR ceilings late tonight. There are signals for IFR ceilings at KELM, KITH, and/or KSYR, but confidence is too low to include them at this time.

LLWS is also expected tonight before diminishing by 12Z behind the front.

Outlook:

Sunday afternoon...Occasional lingering ceiling restrictions possible along with a few isolated showers, mainly at the Central NY terminals.

Monday through Tuesday...Scattered rain and snow showers possible, along with possible restrictions.

Wednesday through Thursday...Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...None.