textproduct: Binghamton

WHAT HAS CHANGED

Fog, some of which could be locally dense was added into the forecast this evening and overnight; especially across the higher elevations of NE PA and the Catskills.

Temperatures were lowered through tomorrow with a combination of east-southeast flow into tomorrow morning and a strong low level inversion trapping moisture near the surface. The biggest temperature changes were from I-81 on east. Given the stable layer in place, thunder chances were also reduced across CNY toward the Southern Tier through tomorrow afternoon.

KEY MESSAGES

1) A cold front will bring a round of rain showers tomorrow, especially late in the day and at night. A few thunderstorms may also develop and result in gusty winds and small hail, mainly west of I-81.

2) Above normal temperatures are expected this weekend through at least the middle of next week. This warm weather, combined with multiple rounds of rainfall will bring an increasing risk for some flooding, perhaps including isolated ice jams.

DISCUSSION

KEY MESSAGE 1...

East to southeasterly flow across the area is expected to keep cloudy and damp conditions in place through the rest of the afternoon right on through early tomorrow morning for most locations along with some patchy fog. A strong low-level inversion in place trapping in moisture near the surface combined with strong warm air advection overnight will also contribute to spotty drizzle especially in the higher terrain. Low temperatures tonight were lowered, especially east of I-81 resulting in a wide range of lows from the low to mid 30s across the Catskills to the low to mid 40s farther west toward the Finger Lakes.

As the flow becomes more southerly tomorrow and a warm front struggles to push north and eastward across CNY, a battle zone looks to set up over the region out ahead of an approaching cold front. Areas west of I-81 look to break into the warm sector with temperatures rising into the mid 50s to the lower to mid 60s (and dew points potentially reaching the mid and upper 50s), while a strong inversion remains in place, holding temperatures down farther east in the upper 40s and low 50s. While NAM model soundings keep the inversion in place through tomorrow evening across the entire CWA, GFS soundings show the inversion weakening west of I-81, especially from around the Finger Lakes toward Syracuse Metro which can allow for some breaks of sunshine.

By the evening, a cold front will be advancing toward the area from the west bringing a round of rain showers and isolated thunderstorms. PWATs rise to around 1.00 to 1.25 inches, so some locally heavy downpours are possible. There is some elevated instability noted, with 500 - 1000 J/kg of MUCAPE along with 50-60kts of 0-6km bulk shear but lapse rates look pretty poor until the actual cold front moves through later on.

If the low level inversion can mix out like the GFS shows, then a few of these showers and isolated thunderstorms could produce some locally strong winds, mainly west of I-81 and possibly some small hail. However, the greater risk for any severe thunderstorms will likely be west of our region, across western NY and southward into the Ohio Valley, but there is a small potential for some strong thunderstorms to persist into our region tomorrow evening. As a result, SPC has parts of our region west of I-81 highlighted in a "Marginal Risk" for severe thunderstorms in their Day 2 Convective Outlook.

KEY MESSAGE 2...

Above average temperatures will be in place Sunday through midweek with high temperatures expected to be the 60s areawide Monday and Tuesday (with some valley locations making a run at 70 degrees Tuesday from the Twin Tiers south into NE PA). Dry conditions are largely expected through Tuesday allowing current river and stream rises that are expected from locally heavy rainfall later tomorrow into tomorrow evening to recede a bit before the potential for decent rises likely returns midweek with a well organized system projected to move through Wednesday or Thursday. Rivers and streams will need close monitoring during this timeframe for potential flooding, including possible isolated ice jams.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

A complex low-pressure system approaching from the Great Lakes will maintain restrictive flight categories across the regional terminals through the forecast period.

Currently, a mix of IFR/LIFR (KBGM, KELM, KITH) and MVFR (KSYR, KRME, KAVP) prevails. Low-level moisture trapped beneath a strengthening inversion is keeping ceilings suppressed, with localized fog/mist (BR) reducing visibilities primarily at the higher elevation terminals and even into some valley locations.

Expect CIGs to lower slightly overnight and into Saturday morning. There will be some minor improvement heading into Saturday afternoon, but IFR CIGs will remain much of the time at BGM and AVP. ITH and ELM will be on the edge of the lower stratus cloud deck by Saturday afternoon, and could occasionally scatter out or lift to VFR...but confidence is low and uncertainty remains. SYR has the highest potential to break out into VFR conditions on Saturday, with just sct to bkn clouds around 4-6k ft expected much of the day. RME will likely remain MVFR/MVFR fuel alternate all day Saturday.

The primary concern overnight and into Saturday morning shifts to Low-Level Wind Shear (LLWS). A potent low-level jet (LLJ) will develop at ~2kft, with southwesterly winds increasing to 35-45 kts. This will create significant speed and directional shear as surface winds remain generally out of the southeast. Surface gusts will also begin to mix down after 07Z-10Z, with gusts of 20-25 kts possible, particularly at KSYR and KITH.

Outlook:

Saturday Night...CIGs could drop lower again across the entire area. Showers and possibly a thunderstorm as a front moves through Saturday evening into the overnight.

Sunday...MVFR CIGs possible in the morning, then becoming VFR.

Monday and Tuesday...VFR expected.

Wednesday...Rain expected with MVFR to IFR ceilings possible.

BGM WATCHES/WARNINGS/ADVISORIES

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