Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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
917 FXUS61 KCLE 200532 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 132 AM EDT Fri Sep 20 2024 .SYNOPSIS... High pressure will continue to influence the region through Friday. A weak cold front will approach Friday night before dissipating as the ridge remains in control through the weekend. Low pressure will track northeast out of the Plains across the Central Great Lakes during the early part of next week. && .NEAR TERM /THROUGH TONIGHT/... 9:00 PM Update... Forecast remains on track as high pressure remains over the region. Overnight lows will dip into the upper 50s, low to mid 50s across interior NW Pennsylvania. Still expecting for patchy fog to develop with the best chance of fog occurring in the Toledo area. Previous discussion... High pressure remains over the area with cumulus clouds seen on satellite imagery inland and a lake shadow down wind of Lake Erie. A few light echos have been noted on radar near the Pennsylvania/New York border but will not amount to more than a few sprinkles in eastern Erie County PA late this afternoon. Otherwise skies will clear overnight with a few patches of fog returning again. Most likely area of fog will be towards Toledo with light easterly flow off the lake trapping increased moisture below the inversion before winds veer slightly to southeasterly. The coverage of fog is expected to be a little lower as slightly drier air tries to work in from the west. Upper level ridge axis will shift just east of the area on Friday. We will see a little return flow develop on the back side of surface high pressure and ahead of a weak front approaching from the west. It was interesting to note this morning that both the 06Z and 12Z GFS was initializing with nearly a 10 degree low bias in dewpoints upstream across Illinois. While temperatures are forecast to trend 2- 4 degrees warmer on Friday, the GFS MOS guidance was much warmer than other sources, possibly due in part to these initialization problems upstream. Kept the forecast in line with the previous forecast values and leaned towards other guidance sources given the initialization concerns on the GFS. Highs will be above normal on Friday ranging from low 80s east to upper 80s or even 90 in the southwest fringe. Winds should be light enough that lake breezes will develop again during the afternoon. Surface low pressure will approach Hudson Bay on Friday night. A weakening front will extend southward into the area and be on our doorstep Friday evening. A narrow ribbon of moisture advection will be focused into the area bringing the chance of a few showers or possibly a thunderstorm on Friday night. Considerable moistening of the airmass will need to occur before rain reaches the ground but weak instability with MU CAPE values of 300-700 J/kg does spread east across the forecast area. Raised pops slightly and expanded east a little faster as the associated shortwave trough crosses Lake Erie. Outside of any thunderstorms, rainfall amounts will be light with generally a tenth of an inch or less. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... A shortwave will continue to track through the region on Saturday. With a decent lift and dew points well into the mid 60s, there will be a chance of PoPs for the central and western portion of the CWA. Don`t expect much in the way of measurable precipitation with this system as it will be moving fairly quick and the weakening boundary. There will be break in between system Sunday with a small ridge building in behind the shortwave with drier conditions. A more potent system will begin to enter the region Sunday night as a low pressure system moves northeastward from the Great Plains. The NBM has trended up on the chance of precipitation for the day on Sunday, though if any, it will be localized to the western counties of the CWA. That being said, PoP chances have been bumped up to chance for the areas west of I-71. Temperatures for Saturday and Sunday will still be in the mid to upper 80s and overnight lows in the mid 60s. && .LONG TERM /MONDAY THROUGH THURSDAY/... Monday we will see the greatest chance of precipitation as a cold front pushes into the region in the afternoon/evening. There is more confidence in increasing to high 50 PoPs during this time period for the majority of the CWA during one point or another Monday/Tuesday. There will be some decent instability with the frontal boundary as it pushes through, so there will be chance of general thunderstorms but don`t expect any severe at this time. Precipitation chances should diminish overnight into Tuesday though will pick up again into Wednesday as the surface low stalls out to the east. Depending on when/where the low starts to stall we be the main factor in which areas of the CWA will see showers Wednesday and Thursday. Will keep watch on rain totals as WPC has introduced a MRGL ERO for the CWA for Monday/Tuesday. Temperatures should start to fall off with this system and a northerly flow afterwards with highs being in the mid 70s and lows in the mid 60s. && .AVIATION /06Z Friday THROUGH Tuesday/... Light winds, clear skies, and saturated lower levels will result in patchy fog across the area, including KTOL/KFDY/KMFD/KCAK/KYNG. There`s potential for non-VFR conditions at all of the aforementioned TAF sites, but the greatest chance will be at KTOL/KCAK/KYNG starting in the predawn hours and continuing through about 12-13Z. Otherwise, anticipate VFR through the majority of the TAF period until shower chances begin to increase from the west in the last 6 to 9 hours of the TAF period. Still some uncertainty in shower coverage, placement, and timing through 06Z Saturday so omitted from the TAFs at this time, but there`s a solid chance that at least VCSH will be introduced in subsequent updates. Winds will be light and variable tonight before becoming southwesterly 5 to 10 knots Friday afternoon and more southeasterly Friday evening. A lake breeze will produce northeast winds at KERI and KCLE during the afternoon and early evening. Outlook...Brief non-VFR possible in showers late tonight into Saturday with better chances of periodic non-VFR in showers and possibly thunderstorms Sunday night through Tuesday. && .MARINE... There will continue to be a easterly flow across the lake with the high pressure situated to the east. A lake breeze should develop Friday afternoon/evening, but will be weaker than previous days with the approaching cold front. During the overnight hours winds will shift out of the southeast at 5-10 kts. The cold front on Saturday will be fairly weak, so impacts for the lake should be minimal. Sunday afternoon should see another day of a lake breeze setting up before another cold front moves into the region on Monday. Ahead of the front winds will be generally out of the south at 10-15kts until the boundary crosses the area and flow shifts to be more northerly into the mid-week. At this time, no small craft headlines are expected but there may be some windows with the approaching system early next week. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...KEC NEAR TERM...KEC/Iverson SHORT TERM...Kennedy LONG TERM...Kennedy AVIATION...Maines MARINE...Kennedy