Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 221024 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 624 AM EDT Mon Apr 22 2019 .SYNOPSIS... High pressure will build into the eastern Great Lakes today and bring a return to dry weather and warmer temperatures. Dry weather will last through Tuesday morning before a cold front crosses the region and brings showers and possibly a few thunderstorms to the area Tuesday afternoon and evening. High pressure will build back into the eastern Great Lakes Wednesday with a return to mainly dry weather. && .NEAR TERM /THROUGH TONIGHT/... IR satellite imagery showing low stratus has expanded and become widespread across the entire area. Overcast skies will continue through midday with a shallow layer of low level moisture trapped beneath a steep inversion. Expect increasing amounts of sunshine this the afternoon after diurnal warming erases the low level inversion and mixes out the field of low level moisture. Temperatures will run just a little above average, with low 60s in most locations. It will be cooler along the lakeshores, especially the south shore of Lake Ontario where a northeast breeze will develop. High pressure will remain in place tonight. This will bring a continuation of dry weather, with mainly clear to partly cloudy skies as a few patches of mid/high clouds cross the region. Lows will be in the upper 40s across Western NY, and low to mid 40s east of Lake Ontario. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... Ridging at all levels will be found over the eastern Great Lakes early Tuesday. However, over the course of the day the upper level ridge axis will shift east in advance of an approaching shortwave trough which will introduce a round of showers and thunderstorms to the eastern Great Lakes late in the day. With that said, a vast majority of the day should be dry and on the mild side with temperatures approaching the mid 70s, except near the influence of the cold lakes. Speaking of which, Lake Erie still has a fair amount of ice on the eastern end of the lake with water temperatures still running in the 30s. Lake Ontario isn`t much different temperature wise both of which will likely play a role in quelling convection. Regarding convection, low pressure over the SOO of Michigan will continue to track ENE into Canada nearing the boarder of Ontario/Quebec with the cold front just to our west by late in the afternoon. Associated height falls with the pre-frontal trough, along with moisture advecting into the lower lakes (PW values of around an inch, not overly impressive), and favorable jet dynamics over New York State (left exit region of a 90-100 knot H250 jet) will allow for showers and scattered thunderstorms to develop just ahead of the cold front. Although, as mentioned above the cold lake temperatures this time of year will act as a barrier to any upstream convection. It`s likely that the initial round of storms with the pre-frontal trough will be sparse in coverage and then likely develop or redevelop fairly far inland from both lakes as a healthy SW`erly flow off the lakes will be present. Behind the pre-frontal trough the cold front will quickly approach the lower lakes, forcing along the front will most likely lead to a better chance for showers or a thunderstorm as it crosses Western and then North Central NY. Although, areal coverage at this point still doesn`t look to be all that impressive and lacking significant instability with only 300- 500 J/kg available per latest HIres guidance. Have kept POPs at current levels with some uncertainty in regards to expected areal coverage for showers and thunderstorms. Tuesday night, the deepening low pressure system will continue to slowly track east passing by to the north of the lower lakes as it head towards New England. Cyclonic WNW`erly flow around this feature will advect a drier and much cooler air mass into the eastern Great Lakes behind its front. As this occurs showers will end from west to east across most of the region overnight. Although, a few showers will linger across the North Country as wrap around moisture works across this region and impacts upslope locations as the low slowly pulls away Wednesday. Wednesday, in the wake of the departing surface low high pressure at all levels will begin to build into the eastern Great Lakes. Look for gradual clearing as subsidence takes hold with mostly sunny skies enveloping the forecast area. With a cooler air mass in place (H850T hovering near 0C or just below) look for highs 10-15F degrees cooler areawide with 50s to low 60s across the lower lakes. Surface high pressure will continue to influence the lower lakes Wednesday night as it track east passing by to our south through PA/MD. Good radiational cooling will take place under clear skies and light surface winds resulting in temperatures falling back into 30s to low 40s. Thursday, surface high pressure exit off the Mid-Atlantic coast in advance of the next upstream system plunging southeast across the upper Great Lakes. However, the surface high will maintain one more day of dry conditions and warming temperatures as return southerly flow develops across the region. After a chilly start look for temperatures to rebound into the low to mid 60s. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... A low amplitude pattern wavering over the northern tier of the country will make up the northern branch of a split flow that will be found across the Lower 48 throughout this period. As such...we can anticipate that temperatures for our forecast area will average within a couple degrees of normal. This will also keep our region from experiencing any significant weather outside of a complex frontal passage late Thursday night and Friday. Although cooler, the first half of the weekend looks pleasant as brief ridging builds in at all levels Saturday. With a cooler airmass in place, high temperatures will run a few degrees below normal with 50s to lower 60s. The next system, with Pacific NW origins, heads east with increasing chances for showers Saturday night into Sunday. Although, at this point there is a fair amount of track and timing difference amongst the different guidance packages. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... Widespread stratus with MVFR CIGS will continue through midday as low level moisture remains trapped beneath a steep inversion. The low stratus will mix out during the early afternoon as diurnal warming erases the low level inversion. This will bring a return to VFR areawide for the afternoon. High pressure will drift east of the area tonight with a continuation of dry weather and VFR conditions as a few patches of mid/high clouds cross the region. Outlook... Tuesday...VFR in the morning, then VFR/MVFR with showers and a chance of thunderstorms in the afternoon and evening. Wednesday...Mainly VFR. A chance of showers east of Lake Ontario. Thursday...Mainly VFR. A chance of showers late. Friday...VFR/MVFR with a chance of showers. && .MARINE... High pressure will build across the eastern Great Lakes today and then drift east tonight, with light winds and flat wave action through Tuesday morning. A cold front will then cross the region Tuesday afternoon and evening. Southwest winds will increase Tuesday ahead of this system, then become west behind the front Tuesday night and Wednesday. This will likely produce a period of Small Craft Advisory conditions on the lakes, with the strongest winds on Lake Ontario. && .EQUIPMENT... The KBUF WSR-88D radar will be down most of this week for a scheduled upgrade. The radar will be down beginning Monday morning April 22, with a planned outage lasting 5 days until Friday April 26. During the upgrade, the transmitter will be refurbished including the installation of new fuses and cables. Some of the components being replaced are original to the radar, which is now over 20 years old. The transmitter refurbishment is the second major project of the NEXRAD Service Life Extension Program, a series of upgrades and replacements that will keep our nation`s radars viable into the 2030`s. This is the second project in the NEXRAD Service Life Extension Program. The first was the installation of a new signal processor. The last two phases of the project are the refurbishment of the pedestal, and refurbishment of equipment shelters. All phases are expected to be complete in 2022. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...AR LONG TERM...AR/RSH AVIATION...Hitchcock MARINE...Hitchcock EQUIPMENT...Hitchcock

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