Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 191809 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 209 PM EDT Thu May 19 2022 .SYNOPSIS...
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A warm front will cross the eastern Great Lakes late tonight and Friday, and may produce a few brief showers and possibly an isolated thunderstorm. The warm front will usher in a very warm and moderately humid airmass for Friday afternoon through the weekend. The warm and unstable air may support a few showers and thunderstorms, especially on Sunday when a cold front crosses the region.
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&& .NEAR TERM /THROUGH FRIDAY NIGHT/...
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A mid level shortwave will move east into Eastern NY this afternoon, with diminishing forcing allowing the last of the scattered showers east of Lake Ontario to end. Widespread low clouds early this afternoon will give way to increasing sunshine from west to east through the rest of the afternoon and early evening as drier air and subsidence in the wake of the trough move into the region. A weak bubble of high pressure will cross the eastern Great Lakes this evening with dry weather. A warm frontal segment will then race from southwest to northeast across the area overnight. Increasing isentropic upglide and moisture transport will bring a period of cloud cover along and ahead of the warm front. Most of the showers should remain on the Canadian side of the border, although a few sprinkles or light showers may cross the North Country early Friday morning with the passage of the warm front. Our attention then turns to an interesting feature for Friday that is largely the result of prior upstream convection. A well defined MCV emerged from overnight convection across Kansas. This MCV will likely result in another MCS tonight across the Ohio Valley, which will then result in a 3rd re-incarnation of a convectively augmented vorticity maxima crossing PA and southern NY Friday. This feature will provide mesoscale ascent and enhanced low level flow and moisture convergence. The best juxtaposition of moisture, forcing, and instability will likely stay south of our region across PA and the northern Mid Atlantic. Nonetheless, there enough forcing from the northern flank of the shortwave to support a period of clouds and a chance of showers moving from southwest to northeast across the area on Friday. Given the inherent uncertainty with track, timing, and strength of these convectively produced MCVs, have just kept POPS in the chance range for now. Highs will likely reach well into the 80s by late afternoon Friday in a strong warm advection pattern. The caveat to this, if clouds and showers become too widespread during peak heating this could keep temperatures lower than forecast. The showers from the shortwave will end by mid afternoon across Western NY, and early to mid evening east of Lake Ontario. This will leave dry weather and partly cloudy skies to prevail for the rest of Friday night. SSW gradient winds will stay up overnight, and combine with the passage of a notable low level thermal ridge to keep temperatures sultry overnight, with lows in the lower 70s on the lake plains of Western NY and mid to upper 60s elsewhere.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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...Strong Thunderstorms Possible Sunday... The overall pattern will remain fairly progressive during this period...as an amplifying ridge off the East coast will give way to energy being ejected out of a broad western conus trough by Sunday evening. This scenario will support above normal temperatures for the weekend...particularly through Saturday when the mercury will average a solid 15 to 20 degrees higher than 30 year normals. The summer warmth will be brought to an end with the passage of cold front on Sunday that could also induce strong to severe convection. The details... The aforementioned ridge off the coast will amplify somewhat on Saturday. This will keep the cold frontal boundary stalled to our west while keeping a continuous feed of very warm air flowing into our region. H85 temps in the vcnty of 18c during the afternoon should easily mix and support max temps of 85 to 90...with the higher end of that range being targeted in the Genesee valley and in some of the valleys of the Srn Tier. Conversely...lake breezes will keep it notably cooler near the lakes...like in downtown Buffalo where the mercury should not climb out of the 70s. In regards to pcpn...the majority of the day will be rainfree. However... convection is likely to develop along a slow moving lake breeze boundary off Lk Erie. Associated showers/tstorms will move east by late morning/midday while slowly building northeastward in the increasingly unstable environment (ie diurnal heating). There is a suggestion by some of the guidance packages that the remnants of an EML may be over the region at this time...so any lake driven convection will have to be closely watched. The area least likely to experience any pcpn will be in the corridor from the BUF metro area northeastward to Batavia to the western suburbs of Rochester...and also in the Thousand Islands region. Any convection that does fire up Saturday evening will wane with the setting sun early Saturday evening. This will leave a mainly dry night in place along with summery mins averaging in the mid 60s. Sunday is guaranteed to be more unsettled...as a fairly strong cold front will push through our forecast area. While the actual front is likely to move through during the afternoon...a pre frontal trough will make its way through during the morning. This seems to be how the finer resolution guidance is resolving the synoptic pattern on Sunday...and its also the climatologically favored solution. There is also an inclination for the stronger convection to be found with the pre frontal trough...but this is not worth fine tuning at this point. Just be aware that there will be sufficient instability for convection...with added synoptic forcing and 35-40kts of shear to present the risk for strong to severe thunderstorm activity. This threat has been echoed in the Day 3 outlook from SPC...which paints our forecast area within a marginal risk area for severe weather. Have thus added some enhanced wording to the forecast and will also introduce this scenario to the HWO product. As the cold front exits t our east Sunday night...the associated convection will die off during the evening with notably cooler air overspreading the region during the overnight. Temps by daybreak Monday should largely be in the 40s.
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&& .LONG TERM /MONDAY THROUGH WEDNESDAY/... Large Canadian high pressure will be found over the Lower Great Lakes Monday and Monday night. This will guarantee fair cool weather for our forecast area to start the new work week. As we head deeper into the week though...a near zonal flow over the country will amplify with cyclogenesis found over the plains. This combination will lead to two things for our weather. The first will be a warming trend to above normal temperatures again by Wednesday. The second will be a return to unsettled weather as a storm system will likely pass to our west Wednesday and Wednesday night. Pops have been raised a bit for both of those periods. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Scattered showers east of Lake Ontario will end this afternoon as a mid level trough moves east of the area. Widespread MVFR/IFR CIGS will scatter out and improve to VFR from west to east through the rest of the afternoon and early evening. A warm front will cross the region from southwest to northeast overnight, with a period of VFR mid level clouds. Most of the showers along the warm front will stay north of the Canadian border, although a few light showers or sprinkles are possible around 12Z Friday across the North Country. Another shortwave will cross the eastern Great Lakes from southwest to northeast during the day Friday. This may support a few brief showers and a limited window of opportunity for MVFR CIGS, otherwise VFR will prevail most of the day. Outlook... Saturday...Mainly VFR with a chance of a few showers and thunderstorms in the afternoon and evening. Sunday...VFR/MVFR with showers and thunderstorms likely. A few storms may be strong. Monday and Tuesday...Mainly VFR.
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&& .MARINE...
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Southwest winds around 15 knots will bring choppy conditions to Lake Erie through early this evening, although winds and waves will remain below Small Craft Advisory criteria. Winds will be lighter on Lake Ontario. Southerly winds will increase into the 15-20 knot range later tonight through Friday night and produce choppy conditions on Lake Erie and Lake Ontario, although the offshore wind component will keep the most significant wave action in Canadian waters.
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&& .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...RSH LONG TERM...RSH AVIATION...Hitchcock MARINE...Hitchcock

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