Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
377 FXUS61 KBUF 250815 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 415 AM EDT Sat May 25 2024 .SYNOPSIS... While today will not be a complete wash out...showers and gusty thunderstorms will develop during the midday and afternoon in response to a pair of fronts moving through the area. Weak high pressure will then allow fair weather to return later tonight with the finest weather of the weekend slated for Sunday. Looking at the end of the long Memorial Day weekend...a complex storm system over the Upper Great Lakes will support very unsettled weather for Monday...including the potential for drenching thunderstorms. && .NEAR TERM /THROUGH SUNDAY/... Gorgeous weather this morning will deteriorate during the course of the day with showers and thunderstorms becoming likely for many areas during the afternoon. Those with outdoor activities planned should keep an eye to the sky and pay attention to updated forecasts and possible statements/warnings regarding the risk for strong thunderstorm activity. The details... Stacked low pressure over the prairies of Manitoba will push a far reaching occlusion across the Upper Great Lakes today with a poorly organized sfc low along the boundary extending a warm front through our region. While beautiful weather will persist over the forecast area this morning...a modest 30kt low level jet impinging upon the advancing warm front will lead to some showers and isolated thunderstorms over the western counties by midday. This activity could initially be focused along a low level convergence zone that will extend from Niagara county eastward to Wayne county. Showers and thunderstorms will then spread across the Eastern Lake Ontario counties...as the warm front will advance to the northeast this afternoon. In the warm sector behind the warm front...notably more humid air will serve as a breeding ground for more robust convection over the western counties during the mid and late afternoon. PWAT values will approach 1.5" with Td`s climbing to arnd 60 F. This moisture rich environment will encourage convection to include torrential downpours...and with bulk shear values forecast to be in the vcnty of 25-30 kts...there could be some storms that could contain hail and/or strong wind gusts. The greatest threat for strong thunderstorms over the western counties will take place between 2 and 6 PM ahead of a cold front. These storms will then make their way across the Eastern Lake Ontario counties between 5 and 8 PM. By sunset...the strongest convection should be east of our area with partial already taking place over the far western counties. The residual showers will continue to end from west to east throughout the evening. This clearing...coming on the heels of fairly widespread convection...could lead to some late night fog and stratus as we push into the wee hours of Sunday morning. The nicest day of the three day weekend can then be expected on Sunday...as a burgeoning shortwave ridge and corresponding weak sfc high will move across the forecast area. While there may be some low clouds around to start Sunday morning...all areas can fully anticipate sun filled skies for the midday and afternoon. It should be a fine day for outdoor activities with sunshine boosting afternoon temperatures into the mid 70s to near 80. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... A shortwave trough over the Pacific Northwest this morning will track southeast into the central Plains by Sunday morning. As the trough tracks southeast, a sfc low will develop lee of the central Rockies and center of the mid-Mississippi Valley by Sunday evening. Out ahead of the sfc low and shortwave trough a warm front will push north crossing the NY/PA line during the late evening and overnight on Sunday night. As the front pushes north, showers along the front will move into the forecast area (around Midnight), becoming better organized as a shortwave trough tracks along the front. There is still uncertainty among guidance for Sunday night as too how organized the showers become, in part due to timing differences of the warm front and the shortwave trough. By Monday morning, the sfc low will be centered over lower Michigan, and continue to track northeast, centering near the Georgian Bay by Monday evening. The system will also start to occlude in the process, becoming more vertically stacked with its mid-level low. This will keep the region within the warm sector of the system for Monday. Thunderstorms are also expected starting early Monday morning, continuing through most of the day. This will be the result of large scale forcing, increasing instability values of over 1,000 J/kg and bulk shear values of around or a little over 30 knots. An influx of GOMEX moisture, combined with the large scale forcing and forcing from a LLJ over the region will result showers that will have some heavier rainfall rates. Increased potential for heavier showers within thunderstorms expected as well. With the above mentioned instability and shear values, the potential exists for at least strong thunderstorms with gusty winds, with the Storm Prediction Center placing much of the forecast area in a `Marginal Risk` for Monday. The best potential for thunderstorms will be south of Lake Ontario. Monday night, steadier showers will track northeast and coverage of the showers will become less through the night from west to east as an occluded front pushes northeast and east into Canada & New England. Some lingering/embedded thunderstorms will still be possible through the first half of the night. Widespread rainfall amounts for Sunday night through Monday night of half to one inch is possible for most of the forecast area, with the highest amounts expected for areas east of Lake Ontario. Localized higher amounts are also possible due to thunderstorms as well. Temperatures for Sunday and Monday night will be in the upper 50s to mid 60s, with Monday night being the slightly cooler night behind the passing front. Monday afternoon temperatures will be in the upper 60s to near 80 from the higher terrain to the lower elevations. && .LONG TERM /TUESDAY THROUGH FRIDAY/... The departing vertically stacked system from earlier in the week will continue to cause showers into the middle of the week as it will take a few incoming troughs to finally push it out of the region. There will also be a few passing cold fronts that pin wheel around the system within the cyclonic flow. Showers should start to taper off by the afternoon on Wednesday. Mostly dry conditions expected from Wednesday night through the rest of the week as a large area of high pressure and large ridge move into the eastern half of the CONUS. Temperatures will be below normal for most of the period, with afternoon highs returning to near normal by Friday. Wednesday and Thursday will be the coolest days with high temperatures around 5 to 10 degrees below normal. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... While VFR conditions can be expected for the vast majority of today...the passage of a pair of frontal boundaries will support some gusty thunderstorms during the midday and afternoon. The greatest risk for the convection over the western counties will come between 18 and 22z...and for sites east of Lake Ontario between 20 and 00z. Convection from the afternoon will move out of the area during the evening hours. While this will leave primarily VFR conditions in place through 06z...clearing skies will lead to some areas of fog and stratus that will result in fairly widespread MVFR to IFR weather through daybreak Sunday. Outlook... Sunday...Improving to VFR. Monday...Restrictions likely with showers and thunderstorms. Tuesday and Wednesday...Restrictions possible with showers. && .MARINE... Winds across the Lower Great Lakes will become more variable today...as a warm front will push through the region. This could allow for some lake breeze circulations to develop. A few gusty thunderstorms will be possible during the afternoon ahead of an approaching cold front with the potential for locally higher winds and waves. With the cold frontal passage winds turn east-northeasterly generally under 10 knots Sunday...as high pressure will briefly build across the lower Great Lakes. More notable winds will occur on Monday into Tuesday with increasing southerly winds early Monday taking on a more west-southwesterly component Monday afternoon into Tuesday. Winds could nudge into the 15 to 25 knots range with possible small craft headlines needed during this time period. Scattered gusty thunderstorms will also be possible Monday. Boaters should continue to monitor the forecast, especially given the holiday weekend which will likely increase boating activity. This will especially be the case on Monday as conditions on the lower Great Lakes will likely deteriorate. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...SW LONG TERM...SW AVIATION...RSH MARINE...TMA