240 FXUS61 KBGM 211429 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 1029 AM EDT Sun Jul 21 2019 .SYNOPSIS... A cold frontal boundary will move through today bringing in cooler weather by Monday. An area of low pressure will move along the cold front to bring our area another round of showers Monday and Monday night. High pressure with drier weather builds into the region for the middle of the week. && .NEAR TERM /THROUGH TONIGHT/... 1030 am update... Only minor changes made to the forecast to incorporate latest visible satellite imagery and latest surface observations. Forecast remains basically the same. Previous Discussion... Some scattered showers and thunderstorms have moved into Steuben county. However, these have struggled to push eastward but a few of them are making it toward Bradford county PA and the Elmira area as of just after sunrise. Will maintain a slight to low chance of thunderstorms this morning across the Southern Tier and far northern PA for the ongoing showers and thunderstorms. Today: A cold frontal boundary will move into the region bringing with it cooler and less humid air. However, this front is still likely to be located north of the Southern Tier of NY and NE PA through the day. Ahead of the front more hot and humid conditions are expected. Modeled boundary layer temperatures do indicate another day of 90-95 for highs across the Southern Tier and NE PA. While, dewpoints come down some today it will still be humid enough for heat index values from around 90 in the Southern Tier to 100-105 in the Wyoming valley and Pike county PA. Heat headlines will remain the same from the previous forecast update. Take precautions if you have to be out in the heat. Further north, welcomed cooler values in the 80's are expected today for highs. As for thunderstorm chances, inhibition will be in place throughout most of the day south of the front which will limit thunderstorm development. However, lift along the front should be able to overcome the inhibition enough for the formation of scattered thunderstorms across NE PA. with the hot and humid airmass CAPE values of around 2,000 J/KG are likely by late in the day with steep low level lapse rates and mid-level dry air. All of these suggest a potential for wet microbursts of gusty winds with any storms. High PW values should result in some heavy downpours with any storms as well. Mesoscale modeling is keying in on the Scranton and Wilkes Barre areas around mid to late afternoon for the initial scattered storms to form. Enough shear (30 kts 0-6KM bulk shear modeled) may allow these thunderstorms to organize into a complex as they depart NE PA by evening. Further north across most of NY, the less humid airmass behind the front should prevent anything more than an isolated shower or two after the morning clouds burn off. Tonight: The cold front gets just south of the region but slows and stalls to our south in response to an area of low pressure in the Ohio Valley. Right now it appears that showers and thunder from this feature should hold off until Monday. The less humid airmass will allow lows tonight to slip into the 60's for many locations. && .SHORT TERM /MONDAY THROUGH TUESDAY/... 405 AM Update... Main concern is for locally heavy rainfall in parts of Northeast PA to the Catskills of NY, though overall threat for truly excessive rainfall appears fairly low with the rain spread out over time. Without a doubt, though, a wet period is expected for most of the area Monday through Monday night. Cooler air will have fully overtaken the area by dawn Monday, and highs will be mainly the 70s except closer to 80 in lower elevations of Northeast PA. Models have trended a bit further southeast with surface frontal position and associated instability. However, there will be plenty of forced ascent in a broad right entrance region of a strong upper jet. Resulting isentropic lift north of the front will cause rain to break out quickly across most of the area Monday, with waves of showers continuing into Monday night for most of Northeast PA and mainly east of I-81 in Central NY. With the front positioned southeast, there will be no surface- based instability for the duration of the event, and chances for severe convection appears minimal. However, some instability aloft, north of the front, will manage to get into at least the Poconos-Catskills and perhaps slightly further northwest at times. The highest precipitable water air, in excess of 2 inches, will remain southeast of the area but Poconos-Catskills will be along the steep gradient of moisture and will have longest duration of rain in our area. Expectations for rainfall totals thus are an inch or more for the greater Wilkes- Barre/Scranton metro through the Catskills, with higher amounts perhaps of 1.5-2 inches possible in the Poconos-Southern Catskills where topography and better prospects of embedded convection will enhance rainfall. These overall rain amounts should be well handled, but with frontal position hung up for awhile, there could be ribbons enhanced rainfall training and/or stuck on topography to cause locally higher amounts. Thus there could be ponding of water on roadways and minor water issues in poor drainage areas. Risk for actual flash flooding appears fairly low, but this will need to be monitored closely. Rain totals will be significantly lower further northwest, with only a tenth to quarter inch in the northern Finger Lakes through the NY Thruway corridor. After lows of upper 50s-lower 60s Monday night, another day of 70s can be expected Tuesday. However, this time northwesterly winds will be bringing in much drier air with dewpoints falling into the 50s. Showers will linger mainly east of I-81 Tuesday morning and will continue to diminish as the day carries on. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... 405 AM Update... The long term will be a generally dry and cooler period with with a long wave trough over the area and surface high pressure nosing in from the southwest. With the lowered heights aloft and heating, some instability showers are possible during the afternoon Wednesday and Thursday, with the best chance over the NY counties. However, vast majority of locations will be dry. Temperatures through Thursday will be slightly below the seasonal norms, and thus much lower the extreme heat of late. Some warming is expected as we head into the weekend. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... VFR throughout the TAF period. The previously anticipated MVFR stratus deck has been very slow to develop and much more in the way of widely scattered restrictions. As a result, the MVFR ceilings are looking rather unlikely this morning. By this afternoon, winds will pick up a bit to around 10 knots with a few gusts pushing 20 knots from the west. Confidence is increasing that a few afternoon and evening thunderstorms may develop around KAVP with data showing the 20-22Z window as the most likely timeframe for any thunderstorm. VFR conditions tonight with decreasing winds early. Outlook... Monday through Monday night...Rain and restrictions likely as wave of low pressure moves up along front just to our southeast. Embedded thunder possible as well. Tuesday through Thursday...Mainly VFR other than valley fog for at least KELM in the predawn hours Wednesday and Thursday mornings. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Excessive Heat Warning until 8 PM EDT this evening for PAZ044- 047-048. NY...None. && $$ SYNOPSIS...MWG NEAR TERM...BJT/MWG SHORT TERM...MDP LONG TERM...DGM/MDP AVIATION...MWG