Area Forecast Discussion

WHAT HAS CHANGED

Minimal changes with this forecast update.

KEY MESSAGES

1) Round of showers arrives late tonight with thunderstorms possible Tuesday.

2) Colder weather by the end of the week with some potential for snow.

DISCUSSION

KEY MESSAGE 1...Round of showers arrives late tonight with thunderstorms possible Tuesday.

Surface low will move east across the Great Lakes late tonight and Tuesday, supporting a cold front which will pass southeast across the region Tuesday evening. A leading shortwave trough, just ahead of the front, will support a round of showers late tonight and Tuesday morning across the Niagara Frontier, likely extending east into the North Country. With mid-level lapse rates approaching 7C/km and a presence of an EML and effective shear of 35 to 40 knot due to a 50 knot jet at 700mb, a few thunderstorms can't be ruled out.

Western and north central New York will remain in the warm sector Tuesday as the surface low passes by to the northwest. Lingering clouds and areas of morning precipitation will likely to inhibit diurnal instability. However, where cloud breaks occur, the presence of dewpoints in the low-mid 60s will contribute to modest MLCAPE up to 500-750 J/kg in the afternoon. This could lead to the development of scattered thunderstorms. Favorable shear profiles will support at least some low end risk for isolated severe thunderstorms, with damaging wind gusts the primary threat.

KEY MESSAGE 2...Colder weather by the end of the week with some potential for snow.

A deepening upper level trough will progress eastward into the Great Lakes region Thursday night and Friday. The associated surface low will strengthening across the Great Lakes with a sharp cold front sweeping through on Friday. There is still quite a bit of model discrepancies with this system and leads to varying timing and strength of the overall system. Regardless, this set up will likely bring the potential for strong winds Friday into Saturday. A much colder airmass will surge into the area behind the frontal passage with pre-frontal synoptic rain showers eventually giving way to lake effect rain and snow showers.

AVIATION /18Z MONDAY THROUGH SATURDAY/

MVFR/IFR CIGs remaining across central New York early this afternoon as gradual improvement to VFR has occurred across far western New York (KIAG and KJHW), but flow off Lake Erie has maintained MVFR CIGs at KBUF. A gradual improving trend should continue the rest of the afternoon across western New York, with low conditions remaining at KART into tonight.

Rain showers will arrive early Tuesday morning, supporting conditions gradually deteriorating to MVFR or lower. A break in showers may occur by midday Tuesday before additional chances for showers and thunderstorms develop during the afternoon.

Outlook...

Tuesday night through Thursday...Mainly VFR.

Friday...Windy. Restrictions likely in rain showers.

Saturday...Restrictions possible. A chance of lake effect precipitation.

MARINE

Southwest winds will remain elevated this evening into Tuesday across the lower Great Lakes ahead of an approaching cold front. Although speeds are expected to remain below 20 knots, choppy conditions can be expected at times, especially on Lake Erie.

Chances for thunderstorms increase on the lower Great Lakes late tonight and Tuesday. Isolated storms could bring the potential for stronger wind gusts. The southwest winds will turn northwesterly behind the cold frontal passage. There could be a short period of small craft conditions. High pressure will build over the Great Lakes for mid-week with winds becoming northerly by Thursday.

Strong low pressure will pass through the region and winds will increase behind a cold front with some potential for gales Friday evening into Saturday.

BUF WATCHES / WARNINGS / ADVISORIES

NY...None. MARINE...None.