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
598 FXUS61 KBUF 011757 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 157 PM EDT Mon Jul 1 2024 .SYNOPSIS... High pressure will deliver fair dry weather through Tuesday. Heat and humidity will then make a return on Wednesday out ahead of an approaching cold front...which will bring our next round of showers and thunderstorms as it crosses our area late Wednesday afternoon and Wednesday evening. && .NEAR TERM /THROUGH TUESDAY/... Fair dry weather today as expansive high pressure to our west builds into the Lower lakes. With 850 mb temps running between +8C and +10C range highs will be found from the upper 60s across the higher terrain to the lower 70s across the lower elevations. Tonight...clear skies will promote good radiational cooling with mercury readings to fall back into the mid-upper 40s across interior portions of the Southern Tier/North Country to the lower to mid 50s elsewhere. Tuesday...a return flow on the backside of the departing ridge will allow highs to climb back to the mid 70s to lower 80s. That said...it will still be comfortable will low humidity levels. Enjoy! && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... An anomalously strong (+2std / 20-30yr RI) 596dm subtropical ridge centered over the Deep South during this period will be the dominant weather player for our forecast area...as it will essentially serve as a heat pump for temperatures that will average well above normal while guaranteeing moderately high humidity. The easy part of this part of the forecast period will come Tuesday night when the crest of the mid level ridge will slowly exit to our east...while the associated area of sfc high pressure will be anchored in the vcnty of Long Island. This will assure us of fair dry weather...but mid and high level moisture spilling over the aforementioned ridge will at least partially shroud our moonless skies. It will be noticeably warmer than the previous two nights... as mins will range from the mid and upper 60s across the lake plains to the lower 60s across the higher terrain. While the bulk of Wednesday will be rainfree, a shortwave crossing Lower Michigan in the morning will push a pre-frontal trough across our region during the afternoon. This will support an increasing coverage of showers and thunderstorms from west to east, with wet weather likely across far western NY by early Wednesday evening. The airmass will become moderately humid with Td`s returning to the mid and upper 60s, but more importantly the door will have been opened for the return of GOMEX moisture with PWAT values surging back to around 2 inches. This should allow any convection to include some torrential downpours with LOCALIZED rainfall amounts of 1-2 inches. With modest instability (500-1000J/kg MLCAPE) and bulk shear magnitudes (30-35kts) out ahead of the pre-frontal wave, not out of the question that some storms may be capable of strong wind gusts as well. This potential is reflected in SPC`s latest Day 3 Convective Outlook, which highlights far western NY in a Marginal Risk. Otherwise...it will be quite warm with max temperatures ranging from near 90 across the lake plains to the mid 80s most elsewhere. The pre frontal sfc trough will complete its passage across our forecast area Wednesday evening...while the plume of deep sub tropical moisture will push off across New England. The widespread shower and thunderstorm activity associated with this feature will taper off from west to east in the process. A weak cold front will immediately follow...but with much of the moisture above H700 stripped away, this passage will go relatively unnoticed. In fact, there will be little if any change in the airmass especially near the sfc where Tds will remain elevated within a few degrees of 70. The weak cold front will settle to our south by Thursday morning... lining up west to east from about the Mason Dixon line to the Upper Ohio valley where it will be stalled through Thursday night. One would think that being on the northern side of this boundary that it would be cooler and less humid...but as mentioned there will not be a true airmass change. It will remain very warm and humid for the Fourth of July holiday with mercury levels only a few degrees lower than the day before. From this vantage point...the day should be largely rainfree...but an afternoon shower cannot be ruled out across the Srn Tier. The remnants of a convectively enhanced shortwave are then forecast to move south of our region across PA Thursday night. While most guidance packages favor dry weather across the forecast area, our airmass will be warm and moderately humid so will hold onto slight to low chc PoPs over the southern counties for a passing shower or thunderstorm. Will need to keep an eye on this shortwave as a further north track can`t yet be ruled out and could spell a much more active night than forecast across WNY, especially for the Southern Tier counties. && .LONG TERM /FRIDAY THROUGH MONDAY/... A low amplitude longwave trough will be centered over the middle of the country during this period...and as such there is high confidence that our temperatures will remain above typical early July levels. In regards to precipitation...Friday/Friday night should be the most active part of this period. Remember the stalled frontal boundary to our south (from late Thursday/Thurs night)? Well...a vigorous shortwave and corresponding broad sfc reflection moving across the Upper Great lakes will push the once stalled frontal boundary back towards our forecast area. Guidance is not in agreement as to whether the boundary makes it back through our region...but it should be close enough to support at least scattered shower and thunderstorm activity...especially over the Southern Tier. Can easily see subsequent forecasts raising pops to likely for that particular area. The boundary will finish its passage through our region Friday night. This will be marked by more showers and thunderstorms...and with PWAT values once again swelling to around 2 inches...any convection will have the potential to produce locally heavy rain. This should prove to be the muggiest night of this long term period. As the strong shortwave over the Upper Great Lakes ejects into eastern Canada on Saturday...the aforementioned sfc low will push a cold front though our region. While consensus is that this will occur early Saturday morning...a delayed passage would result in a more pessimistic forecast. At this point though...the front should move through early enough so that an ensuing dry slot will push across our region during the day so that there will only be the chance for an afternoon shower. Once again...little change in temperature and humidity is expected in the wake of the cold front. High pressure over the spine of the Appalachians Saturday night and Sunday will then provide generally rainfree weather over our forecast area to end the weekend. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Some fair weather cu will be found across the area...otherwise VFR will be found at all terminals. Outlook... Tuesday...VFR. Wednesday...VFR, then MVFR with showers and thunderstorms late Wednesday afternoon and Wednesday night. Thursday...Mainly VFR with a low chance of a shower or thunderstorm across the western Southern Tier. Friday and Saturday... Mainly VFR with a chance of showers and thunderstorms. && .MARINE... Northerly flow will produce choppy conditions on both lakes with waves of 1 to 3 feet this afternoon. As the expansive high pressure to our west builds east winds and waves will begin to relax by this evening. Much more favorable boating conditions will then take hold through Tuesday as this high drifts across the Lower Great Lakes and into New England. Freshening southerly winds will then follow for later Tuesday night and Wednesday out ahead of an approaching cold front...however the offshore nature of the flow will help to direct the greatest wave action across Canadian waters...with conditions largely remaining below advisory criteria as a result. Of more concern to boaters will be an increasing potential for showers and thunderstorms as the cold front approaches and crosses the region later Wednesday afternoon and night...with locally higher winds and waves possible in and near any thunderstorms. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...AR/JJR NEAR TERM...AR SHORT TERM...PP/RSH LONG TERM...RSH AVIATION...AR/PP MARINE...AR/JJR