textproduct: Cleveland

WHAT HAS CHANGED

Slowed down rain timing slightly for Sunday. Trended temperatures down for Monday.

KEY MESSAGES

1) An isolated shower or two is possible this afternoon with scattered showers and thunderstorms Saturday afternoon.

2) A widespread rain event of 1 to 2 inches is forecast for Sunday night into Monday resulting in rises on rivers. There is potential for a couple rivers to experience minor flooding.

3) Temperatures will remain slightly below normal for much of the week.

DISCUSSION

KEY MESSAGE 1...

While a broad trough aloft is already in place from the northern Plains to the Ohio Valley to New England, another shortwave trough will slide southeast across Lake Erie this afternoon. The airmass is generally dry, but steep low level lapse rates and lift associated with the shortwave may be sufficient for a stray shower or two to develop in Northeast Ohio or Northwest PA this afternoon. Not expecting thunderstorms except perhaps towards Erie PA where temperatures are cooler aloft.

A ridge of surface high pressure builds east across the area on Friday night followed by another more compact shortwave trough moving through the northwest flow aloft on Saturday. A few showers could move into northwest portions of the forecast area as early as Saturday morning with scattered showers and thunderstorms expanding by midday across central portions of the area and moving southeast. While the coverage is generally expected to be scattered, a couple counties towards Portage, Trumbull, Mahoning may see greater coverage of showers. Trended pops up another 10 percent in the east.

KEY MESSAGE 2...

The upper level trough axis shifts east of the area on Sunday. Meanwhile a fast moving shortwave crosses the Rocky Mountain range with low pressure developing over the Plains and racing eastward. The low is forecast to track across central or northern Ohio and may or may not merge with a closed upper level low aloft rotating into the Upper Great Lakes. Regarding the low track, the 00Z/19 GFS is a little too far south when compared to the GFS ensemble. Prefer a more middle of the road approach like the 00Z/19 ECMWF which does show some phasing with the northern stream by Monday. Slowed down the timing of rain, especially along and east of I-71 on Sunday afternoon with most areas not seeing a steady rain until Sunday night. The track of the low will influence who gets the heaviest rain and higher potential for thunderstorms. Modest instability does look to extend north into the area on Sunday night with strong sheer. Current forecast suggests rainfall of 1-2 inches across the local area but the gradients may be more sharp with training possible along the warm front. Rises on area rivers can be expected and the potential exists for a few to experience minor flooding. Locally heavy rainfall may also be possible if robust convection occurs and trains over the same area. We will need to monitor the forecast position of heavier rainfall. The western half of the area has been included in a Slight Risk for Excessive Rainfall (level 2 of 5).

KEY MESSAGE 3...

Temperatures through the week tend to remain on the cool side of normal. High temperatures will tend to reside in the 70s as we alternate between a northwest flow and zonal flow aloft.

AVIATION /12Z Friday THROUGH Tuesday/

Mostly sunny skies this morning will give way to afternoon cumulus, but VFR will prevail through tonight as high pressure maintains overall control. A few light, diurnally driven showers this afternoon may briefly impact KCAK, KYNG, and KERI, but confidence in anything hitting a terminal is low, so kept VCSH.

WNW winds of 5-10 knots early this morning will increase to 10-15 knots by late this morning, with gusts of 20-25 knots this afternoon before decreasing after 00Z this evening through tonight.

Outlook...Isolated to scattered showers and thunderstorms are possible Saturday afternoon/early evening. Non-VFR would be limited to just the strongest showers/storms. Additional showers and storms are possible Sunday afternoon through Tuesday morning with the potential for more non-VFR coverage.

MARINE

Winds and waves will further decrease early this morning, so allowed all headlines to expire at 06Z. W winds of 5-10 knots early this morning will increase again to 10-20 knots late this morning through the afternoon, and this will build wave heights to 3 to 3.5 feet in the central and eastern basins, but expect conditions to stay just below Small Craft criteria. Nevertheless, it will be a bit choppy again on Lake Erie this afternoon. W to WNW winds will then average 5 to 15 knots tonight and Saturday before turning NW at 5-10 knots Saturday night.

The next period of impactful winds will come late Sunday and Monday as another unseasonably strong low pressure system tracks through the southern Great Lakes. E winds will increase to 15-25 knots late Sunday and Sunday night ahead of the warm front, turning NNE behind the cold front Monday, so Small Craft Advisories are likely with this system. Lighter winds are expected Monday night and Tuesday as high pressure builds across the area.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...None.