951 FXUS61 KBGM 211925 AFDBGM AREA FORECAST DISCUSSION National Weather Service Binghamton NY 325 PM EDT Sun Apr 21 2019 .SYNOPSIS... A slow moving low pressure system will slowly move east across the region into Monday bringing a few showers with it. High pressure will build into the region Tuesday with the next cold front coming through our region Tuesday night and early Wednesday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 1125 am update...Areas of fog that were around the Finger Lakes region earlier this morning have now lifted. Otherwise, current satellite and observations indicates mostly cloudy skies areawide, with some cumulus development as daytime heating increases instability. Near term guidance indicates 2 axis of greater shower coverage this afternoon...one across the western Catskills, into Broome county, then south toward Scranton and the Poconos. Another area of better coverage for showers will be west-central Bradford county and souther Steuben county. There will still be some isolated to scattered showers around even outside of these locations. Models indicate MLCAPE values only around 100 J/Kg and weak mid level lapse rates...therefore still left any mention of thunder out of the forecast at this time. Shower tops will likely only be able to rise around 10-12k ft agl. The mean wind for storm motion in this layer is generally less than 10 kts...so the showers that do develop will be meandering, slow movers. Will keep an eye out for any locally heavy downpours, but PWATS and dewpoints have come down. High temperatures still expected to reach the upper 50s to mid-60s this afternoon. Previous Discussion Below With the sunrise update, the temperature gradient with the front was updated. Otherwise, forecast discussion below on track. An upper level low and mid-level trough will still be in place across the region today and tonight. The frontal boundary which produced the tight temperature gradient last night will become more diffuse today. Enough lingering moisture and a slight amount of instability from steeper low level lapse rates should be enough for a few spotty showers. The highest chances will be mid to late afternoon when the slight amount of instability is maximized but a few spotty showers are still possible in the morning and evening hours. Any precipitation looks light. Highs should get into the low 60's for most locations today with lows in the 40's. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... For Tuesday, the day starts off under a ridge of high pressure from the surface up to the upper troposphere. Skies should begin with patchy high clouds ahead of the next upstream system which was moving through the Great Lakes. There could be some lingering patchy valley fog as well that burns off by late morning. As the day progresses, the ridge slides east and NY / PA comes under a deep southwesterly flow of air. The low- level winds will accelerate during the day as a low- level cyclone and associated cold front reach the Eastern Great Lakes late afternoon and early evening. The low-level ageostrophic winds will be pointing northerly and convergent as an upper level jet streak moves to the upper Ohio Valley and Lower Lakes. Much of NY and northeast PA will be in the left exit region of this upper feature which leads to divergence and southerly ageostrophic winds aloft. Hence the lower level branch of the ageostrophic circulation is what is driving this southwesterly flow in the low-levels. This will lead to moisture and warm advection and low-level convergence in the presence of divergence aloft spreading into NY and PA in the afternoon and evening Tuesday. Additionally, given the above dynamics, there will be strong vertical wind shear and even some turning in the hodograph in the 0-1 km layer. This usually is an excellent set up for severe weather in NY and PA. But, there is a marked lack of instability even in the NAM which usually is most aggressive with the instability fields. NAM Surface based CAPEs are running less than 500 J/kg. Mixed layer CAPE is also generally 100-300 J/kg. The GFS is similar with just slightly less CAPE. Model soundings for both NAM/GFS show that it is initially very dry in the low-levels as well. These are limiting factors for any severe weather and if the models hold, we should see mainly rain showers with scattered thunderstorms late Tuesday into Tuesday night. This is consistent with SPCs Day 3 outlook of general thunder. This still is something to watch for future shifts. It just depends how fast we can moisten up in the low- levels before the cold front and dynamics kick in later Tuesday and Tuesday evening. For now, have POPs increasing from Tuesday afternoon, peaking in the evening and then dropping off after midnight as the front clears the region. For Wednesday, high pressure presses eastward reaching the eastern Lakes by the end of the day. There will be a northwest flow of chilly air aloft across central NY and northeast PA all day with wrap around stratocumulus which will be thickest in northern NY down to the Catskills and thinner farther west and south. With insolation I see this stratocumulus evolving into a cumulus later except from the upper Mohawk valley to Western Caskills where upsloping will counter the dry air mixing into the surface layer. Will have higher cloud cover in these areas and less farther west and south in the afternoon. Some linger light rain showers are possible from the Upper Mohawk Valley to the Catskills mainly Wednesday morning. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Rain chances wrap up Wednesday night as a ridge of high pressure begins to build in. Dry and sunny weather is expected for Thursday with temperatures starting in the upper 30s to low 40s peaking generally in the 60s. Friday becomes a little more interesting, as a surface low heading into the mid- Atlantic while at the same time another shortwave moves through Ontario and Quebec. This will bring in rain chances early Friday ahead of the approaching cold front, which should finally track through the area during the afternoon and evening. Expect morning lows in the 40s and highs in the 60s. A few showers may linger early Saturday with some wraparound moisture and the exiting upper wave, but then much of the weekend is looking dry and sunny with high pressure building over the southeast US. As the ridge starts to slide off to the east during the day Sunday, there are indications for some weak waves to start passing through. A few showers cannot be ruled out, otherwise expect partly cloudy skies. Temperatures will be cooler the rest of the extended period and should start off in the 30s and 40s before peaking in the 50s to low 60s. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... MVFR for KITH through the afternoon for lingering fog and mist, with occasional LIFR over the next couple of hours improving slightly this evening. Mainly VFR for the rest of the sites for the rest of the day, but occasional rain showers may bring in periods of MVFR for KELM, KBGM, and KAVP. Light winds turning mainly to the NW this evening. Additional ceiling restrictions are likely to form again tonight, falling back to IFR or even LIFR before improving to MVFR after 12Z. Outlook... Monday and Monday night...Mainly VFR. Tuesday...Mainly VFR a few restrictions with some showers possible by sunset. Tuesday Night through Wednesday morning... Some restrictions in periods of showers and a chance of thunderstorms. Wednesday afternoon through Thursday...VFR expected. Friday...restrictions possible in scattered rain showers. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MWG NEAR TERM...MJM/MWG SHORT TERM...DJN LONG TERM...HLC AVIATION...HLC