textproduct: Binghamton

WHAT HAS CHANGED

PoPs and QPF were increased in the near term, especially west of I-81 across the Twin Tiers as the NBM was underdone in this area. Wind gusts were increased a bit through early this evening.

KEY MESSAGES

1) Unsettled conditions continue into Monday with locally heavy rainfall possible as a slow moving frontal boundary crosses the region.

2) A warm and humid pattern will be in place mid to late week with chances for showers or thunderstorms each day.

DISCUSSION

KEY MESSAGE 1...

A very moist atmosphere is in place through tomorrow morning out ahead of a slow-moving frontal boundary and supporting upper trough. A broad batch of showers currently lifting north is the first of a few rounds of convection expected to move through into Monday, especially through the morning hours. This first round is producing locally moderate to heavy rainfall as PWATs are currently around 1.70-1.90 inches on the SPC mesoanalysis page and are expected to rise to or exceed 2+ inches tonight into early tomorrow, especially across NE PA into the Catskills. This remains the main corridor for our flash flood concerns overnight and early Monday morning as model soundings still show short MBE velocity vectors with warm cloud heights over 12,000 feet and tall, skinny CAPE profiles after midnight through mid to late tomorrow morning, all adding up to the potential for locally heavy rainfall and training over an area that has seen recent heavy rains. However, confidence is low to medium with this area seeing the heaviest rainfall as this afternoon has seen more steady and locally heavy rain falling over the Twin Tiers west of I- 81 than projected by the NBM (the CAMs have been doing a bit better), but given the convective nature of this system, high resolution models start to diverge in their placement of the heaviest rainfall overnight. With the frontal boundary slowly moving east overnight and a strong Bermuda high slowly shifting west, a strong south to north moisture transport develops between these features which could lead to the heaviest rainfall occurring to our south and east.

Given the uncertainty of where the stripes of heaviest rainfall will set up, a flash flood watch has not been issued at this time, but a few isolated warnings may be possible. One hour county flash flood guidance across the Twin Tiers and Catskills is currently 1-1.50" of rain while 3 hour guidance is 1.70-2.40" of rain. Current flash flood headwater guidance is just under 2" for most points in CNY and western Catskills.

Overall, a general 0.50-1.00 inch of rain is expected through tomorrow afternoon with localized points of 1.25-1.50" or greater possible. Total QPF was a combination of NBM, WPC and CONSall given the struggles so far early in this event and to smooth out any high convective bullseye given the uncertainty.

While the focus has been on the hydro side of things, there is a low risk for some gusty thunderstorms from the Poconos to the southern Catskills Monday. MLCAPE values increase to around 500 J/kg and MUCAPE rises to around or a bit higher than 1000 J/kg with 30-40 knots of bulk shear.

The frontal boundary looks a bit faster in timing today, crossing much of the area by Monday afternoon and early evening. Winds will shift out of the northwest and drier air funnels in as PWAT values fall to less than an inch. High pressure builds in for a brief reprieve from the wet weather for Tuesday and depending on timing of the next feature, possibly portions of Wednesday as well.

KEY MESSAGE 2...

Several features all look to come together to increase chances for showers and thunderstorms from late Wednesday through the end of the work week. The Bermuda high is expected to shift even more west, drawing up plenty of very warm and humid air from the south and driving up dew points. Meanwhile a broad upper trough over the northern Plains, Upper Midwest and Great Lakes will channel waves of energy toward our region and a weakening cut off upper low over the Tennessee Valley looks to gradually drift northeast across the southern and central Appalachians later in the week. The next frontal boundary also looks to try to approach from the west in the Thursday-Friday time frame and perhaps stall a bit. So putting everything together, there will be daily chances for showers and storms with dew points anywhere from the mid 60s to the mid 70s in spots. This will lead to some very uncomfortable conditions with high temperatures mainly in the upper 70s to mid 80s each afternoon.

AVIATION /19Z SUNDAY THROUGH FRIDAY/

Besides at KELM (mainly MVFR), mainly VFR conditions are expected this afternoon with mainly light rain showers. In any brief heavier shower, brief IFR visby restrictions will be possible. Ceilings will gradually lower this evening, first to MVFR/Fuel Alternate, then gradually to IFR. Gradual improvement back to MVFR is expected by the late morning/early afternoon on Monday.

Gusty south to southeasterly winds will be present this afternoon with occasional gusts of 20-25kts. Winds will gradually calm tonight and become light and variable at most terminals.

Outlook:

Monday afternoon...Gradual improvement, with VFR conditions expected late.

Tuesday...Mainly VFR.

Wednesday through Friday...Scattered showers and isolated thunder; associated restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

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