textproduct: Binghamton

WHAT HAS CHANGED

Confidence in thunderstorm formation for today and tomorrow has decreased as forecasted conditions are trending toward lower severe parameters.

KEY MESSAGES

1) Strong high pressure will bring very hot and humid conditions today and tomorrow. Isolated thunderstorms are possible today, with a better chance for afternoon storms tomorrow.

2) A cold front will push through the area Wednesday, bringing scattered rain showers and thunderstorms. Much more seasonable temperature return for the rest of the week and into the weekend.

3) Memorial Day Weekend could have active weather with seasonable temperatures.

DISCUSSION

KEY MESSAGE 1...

Our first taste of summer continues today and tomorrow as a strong Bermuda high dominates the region. The positioning of the high puts us in the NW quadrant of the system, allowing for strong SW flow to advect warm, humid air in from the southern US. Temps currently in the upper 80s and should warm into the low 90s for valley locations in the next few hours. Dewpoints are also hovering around 60F, which is the usually the threshold for when it starts to feel sticky outside. This humid airmass will allow for overnight lows to remain quite warm, with mid to upper 60s expected across the region. Tomorrow will once again be hot and sticky as SW flow continues through the day. There may be a little more cloud cover as a trough moves into the Great Lakes region, so temps could be a couple degrees cooler than today, but it will feel about the same with heat indices in the upper 80s to low 90s. A cold front is progged to slowly slide in from the NW starting Tuesday night, which will drop temps below 60s north of the Southern Tier, and keep temps in the mid to upper 60s along and south of the Southern Tier.

The increasing heat and humidity usually also implies increasing thunderstorm chances, but that is not the case for this set up. The Bermuda high centered off the Carolina coast has a center 500mb height around 592dm. With this strong high so close to the coast, its influence should dominate any thermodynamic processes that would try and get convection going. Looking at the latest model soundings from high-res hourly CAMs, we see a very large and deep inverted V profile due to dry air in the lower atmosphere, with WAA providing a strong cap in the 700-500mb range. CAMs earlier in the day were showing some storms initiating during the early evening hours along the Lake Plain, but the latest runs have backed off, showing a slight chance for some isolated storms moving into NEPA around midnight and the northern Finger Lakes during the overnight hours. These storms would develop off some leftover energy from a MCS currently over IL/IN/MI moves along the edge of the ridge, but confidence is low that this energy would be able to penetrate the dynamics from the strong ridge and generate storms. On Tuesday, the center of the ridge will drift eastward, opening up our area to better chances for thunderstorms from the late morning into the evening hours. Severe parameters for any storm that develops currently looks to be on the low end, with CAPE under 1000 j/kg during the afternoon, mid-level lapse rates around 5-6C/km and 0-6km bulk shear around 30-40kts. One feature that could help get some storms going, especially along the Lake Plain and into the Mohawk Valley, is energy from a shortwave moving across Ontario dipping into our area. Models are showing chances of stronger shear and lift N of the Southern Tier during the late morning to mid afternoon hours that could help develop some storms that could become severe. The big hindrance seems to be morning cloud cover that lingers into the afternoon, reducing surface heating and mid-level lapse rates, which would limit storm development. If the clouds are not as widespread as currently forecast or we can see some clearing by late morning, thunderstorm coverage and severe chances will definitely increase.

KEY MESSAGE 2...

A cold front is expected to slowly move through the area from the NW Tuesday night thru Wednesday as the Bermuda high flattens and moves to the SW and a trough moves in from the Great Lakes. Scattered rain showers and thunderstorms are expected to develop along the front, but coverage and amount of rain still remains somewhat uncertain. The last few model runs are showing less and less rainfall amounts as the front runs into the drier air mass that has been under the ridge for the past few days. The front and associated precipitation is expected to clear the area by the late afternoon hours. A temperature gradient is expected to set up over the area on Wednesday as the front moves through, with upper end highs in the mid to upper 80s across the Wyoming Valley, falling all the way down to the upper 60s across the northern Finger Lakes into the Tug Hill region.

Colder air will once again will filter into the region for the rest of the week, with highs in the mid 50s to mid 60s and lows in the upper 30s to mid 40s. High pressure will dominate with no rain expected thru Friday.

KEY MESSAGE 3...

With the Memorial Day weekend in sight, the weather unfortunately might not cooperate for those who would like to spend the weekend outside with sunny skies and summer like temperatures.

The ridge over our area through the end of the week will slide to the ENE as a trough is currently progged to move into the central portion of the country. The trough looks to eject a shortwave or two into our area Sat and Sun, but the ridge may be strong enough to keep rain out of the area. The positioning of the ridge will keep the cooler airmass in place, with low 60s on Sat and mid to upper 60s on Sunday. Memorial Day could see temps push into the 70s, but depending on how the ridge behaves through the weekend, we could see showers and storms develop.

AVIATION /19Z MONDAY THROUGH SATURDAY/

Mainly VFR conditions are expected through the 18Z TAF period. There is a slight chance of a shower or thunderstorm tonight, mainly after midnight, for ITH, SYR and RME as an upper level shortwave passes by just to the north and west, but confidence is too low to include in the TAF at this time. Isolated to scattered showers and thunderstorms are expected to develop tomorrow, possibly as early as 16-18Z, which can result in some brief restrictions as the afternoon goes on.

West-southwesterly winds with gusts generally around 15 to 20 knots continue through the remainder of the afternoon before becoming light and a bit variable tonight. Southwesterly winds increase again later tomorrow morning and into the afternoon with gusts of 15 to 25 knots expected.

Outlook:

Tuesday afternoon into Tuesday night...Mainly VFR, but isolated to scattered showers and thunderstorms may result in brief restrictions.

Wednesday...Scattered showers and thunderstorms and associated restrictions possible as a frontal boundary moves through the area.

Thursday and Friday...Mainly VFR.

Saturday...Periods of rain and embedded thunderstorms likely along with associated restrictions.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...Air Quality Alert until 11 PM EDT this evening for NYZ062.