textproduct: Binghamton

WHAT HAS CHANGED

Increased forecast rainfall amounts where persistent heavier showers and embedded thunderstorms are training; across eastern Susquehanna, northern Wayne and west-central Delaware counties. The rainfall looks to linger longer across the NY southern Tier and NE PA, perhaps into the mid or late morning hours today. A stripe of 1.5 to 2.5 inches of rainfall seems probable by the time the rain ends late tonight behind the departing cold front.

KEY MESSAGES

1) Locally heavy rainfall possible in a few locations this morning. Then, isolated strong to severe thunderstorms develop this afternoon and evening as a cold front pushes through. The greatest threat will be storms that produce isolated damaging winds and large hail.

2) Drier and cooler weather expected Monday into Tuesday as high pressure moves overhead. Expected a warming trend with a chance for showers for the middle to end of the upcoming work week.

DISCUSSION

KEY MESSAGE 1...

The latest mid level water vapor loop shows a well defined shortwave spinning slowly east into the northern Mid-Atlantic. Out ahead of this feature there is plenty of lift as southwesterly low level jet is in place across Central PA and Central NY. There is deep moisture extending up and above the 700mb layer. Strong upper level divergence is evident across this same area at 250mb to 300mb. There is enough elevated instability for a few lightning strikes in the heavier precipitation currently across the western Catskills and northern Poconos. Further back to the south and southwest there is more instability present, with the latest SPC mesoanalysis showing 500J/Kg of MLCAPE up to Harrisburg and nearly State College in PA. Scattered embedded thunderstorms have already developed in this area, and these will continue to slowly track off to the north and east; becoming more elevated in nature as they move through NE PA and portions of Central NY. It seems with this strong lift and divergence in place that periods of rain, showers and occasional thunderstorms will continue through daybreak and likely even into the mid or late morning hours across NE PA and the NY southern tier....before completely exiting before noon today. The official forecast takes a blend of radar trends, HRRR, 3km NAM and the NBM for hourly PoPs this morning. QPF is a blend of WPC, NBM and latest observed trends. There will likely be a few localized stripes of 1- 2, perhaps 2.5 inches of rain by the time the rain ends late this morning...although most locations will see under 1 inch of rain by noon. There could be isolated areas where ponding of water and excessive rainfall occur. Can't rule out some localized flash flooding as well; and this potential will be monitored very closely.

After the rain exits and ends later this morning there should be some dry time and skies turn partly sunny. It will be warm and humid today with highs reaching the mid-70s to low 80s and dew points in the upper 60s to low 70s expected. This will allow for increases surface based instability later this afternoon, along with increasing bulk shear values between 40-50 kts. As the cold front presses south a scattered line of storms is expected to develop...first across the NW Finger Lakes and Syracuse area...then reaching the NY southern tier and eventually NE PA/Catskills by mid to late evening. These storms could produce heavy downpours, gusty to isolated damaging winds and even hail. SPC maintains the Marginal Risk (level 1 of 5) for isolated severe storm potential for just about the entire CWA later this afternoon and evening.

KEY MESSAGE 2...

A fairly strong cold front is forecast to push through the area early Monday morning. Behind the front much cooler and drier air will advect into the forecast area. 850mb temperatures fall to around +4C by early Monday afternoon. Gusty NW winds are also forecast to develop in the cold air advection regime. Expect sustained winds of 8-15 mph with some gusts to 25 mph possible as the boundary layer becomes well mixed up to 825mb. Despite skies be partly to mostly sunny high temperatures are only forecast to reach the low to mid-60s across Central NY...with mid-60s to around 70 in NE PA. Monday will be quite chilly with widespread valley fog in the forecast. There will be a steep low level inversion developing as mid level warm air advections begins overnight and 850mb temperatures actually rise back to +8C by sunrise. A 1028mb surface high will be directly overhead, helping to keep skies clear and winds very light. Expect very cool overnight lows ranging from the upper 30s to mid-40s in most locations. A few of the normally colder spots could even see mid-30s with patchy frost possible.

Tuesday features ample sunshine and warming temperatures as a strong upper level ridge pushes into the area from the Ohio Valley. Daytime highs should recover into the upper 60s to low 70s, with a few locations up in the mid-70s. Winds turn southerly between 8-15 mph, which will help to boost the afternoon temperatures.

An upper level ridge nudges north into the area for Wednesday, which will bring warmer weather and perhaps a few isolated showers or thunderstorms late in the day. The flow turns more zonal by Thursday, which will keep the warm temperatures around but bring the potential for more showers and thunderstorms. A broad upper level trough develops over the Northeast US by Friday, as the strong upper level ridge retrogrades into the arklatex region. This will start a cooling trend for our area, with still a chance for lingering showers. Next weekend looks to feature near average temperatures with some shower chances Saturday, then generally dry weather next Sunday. Official forecast stuck very close to the blended ensemble guidance for this extended period as exact details remain to be seen.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Rain showers continue over AVP this morning with Fuel Alt ceilings and occasional IFR visibilities. Elsewhere rain has moved out of the central NY terminals, though lingering MVFR to FUel Alt restrictions remain at RME, ITH, and ELM, while BGM is seeing Below Alt Mins. SYR should remain mainly VFR this morning, with brief periods of MVFR possible.

Rain will continue to move out of the area from northwest to southeast through 15Z, with conditions gradually improving from late morning into early afternoon. A cold front may bring thunderstorms this afternoon into early evening, though confidence remains low on exact timing and whether storms will directly impact any terminal. Therefore, PROB30 groups were used to highlight the most likely time frame. Additional restriction may develop again tonight at ELM, BGM, and ITH.

Outlook...

Sunday night...Improving conditions Sunday afternoon but potential fog development overnight.

Monday through Wednesday...Mainly VFR.

Thursday...Potential restrictions with front trying to make its way into the region.

BGM WATCHES/WARNINGS/ADVISORIES

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