textproduct: Cleveland

WHAT HAS CHANGED

Winds have trended higher on Lake Erie Thursday.

KEY MESSAGES

1) Rain will continue across the area this evening, gradually ending tonight. QPF still looks to average 0.25 to 0.50 inch.

2) A pattern change to cooler weather and showers is expected behind a front Friday into Saturday, with the greatest coverage of rain in NE Ohio and NW PA.

3) Gradual warming early next week.

DISCUSSION

KEY MESSAGE 1... Satellite and water vapor loops this afternoon show a mid/upper closed low over the Upper Midwest, with a surface low stacked beneath over northern Wisconsin. This is placing an occluded cold front from Lower Michigan through western Ohio. The front being so far displaced from the closed low, as well as no true cold air source, is leading to limited dynamics with this system. However, a 40-50 knot southwesterly low-level jet is helping to draw a band of deep moisture into the region to support fairly steady rain ahead of the frontal boundary. This rain will continue to be mainly light given the weak dynamics, but expect it to be persistent through the evening. There should be a lull after 00Z as the deepest moisture plume shifts east, but expect one more uptick in showers right along the frontal boundary in the 02-07Z period, especially in NE Ohio and NW PA. This has been a consistent signal in RRFS runs. Total QPF through tonight still looks to average 0.25 to 0.50 inch, so no impacts are expected other than beneficial rain after being dry for almost a full month.

As the mid/upper low lifts through the northern Great Lakes tonight and into northern Ontario Thursday, a dry slot will wrap into the region, so expect dry conditions late tonight through Thursday. This will allow for quite a bit of sunshine Thursday and continued mild temperatures, but it will be breezy due to the relatively tight pressure gradient on the southern edge of the mid/upper low. Expect SW winds to gust to 20-30 knots at times from late morning through the afternoon as sunshine and the dry profile leads to deep mixing.

KEY MESSAGE 2... A stronger mid/upper trough and associated closed low remain on pace to dive through the Upper Midwest and Great Lakes Thursday night and Friday. This will push a stronger cold front through the region Friday, leading to a more substantial airmass change to seasonable temperatures Friday through the weekend (highs in the low/mid 50s). Moisture return ahead of the front is brief before the front pinches it off, so even though showers will gradually push into the region from west to east Thursday night and Friday morning, QPF will be very light. Coverage of showers Friday will be highest in NE Ohio and NW PA where boundary layer winds shifting to W then NW behind the front and 850 mb temps dropping to 0 to -3 C will support lake enhancement, so this will keep showers going through the day in those areas. A transition to pure lake effect rain showers Friday night will continue through at least Saturday morning as NW flow, cold air advection, and wraparound boundary layer moisture continues. This will keep showers going across the "snowbelt" areas of NE Ohio and NW PA, especially eastern Cuyahoga, Lake, Geauga, Ashtabula, Trumbull, Erie, and Crawford Counties. Drier air and a lowering inversion will finally end the lake effect by Saturday night as high pressure noses in from the Mississippi Valley, setting up a dry but seasonably cool Sunday.

KEY MESSAGE 3... Another cold front will drop through the region Sunday night/Monday tied to a mid/upper trough diving through the eastern Great Lakes. This could bring a few lake enhanced showers to NE Ohio and NW PA, but very low-impact since the best forcing will pass to the east. Despite this front grazing the area, temperatures will actually moderate early next week as a continued split mid/upper flow across the CONUS floods Pacific- based air eastward, so expect highs in the upper 50s to low 60s Monday through Wednesday. A stronger trough could possibly bring cooler air the second half of the week, but there continues to be no source region for arctic air anytime soon as most of Canada remains under abnormally high mid/upper heights and mild Pacific air.

AVIATION /00Z Thursday THROUGH Monday/

Mixed-bag of mainly VFR and MVFR with isolated pockets of IFR ceilings across the TAF sites this evening. More widespread IFR ceilings are expected later this evening and overnight at mainly MFD/CAK/YNG, though IFR ceilings could also briefly impact CLE. Conditions will gradually improve to MVFR or low-end VFR by Thursday morning and afternoon from west to east behind a cold front.

Winds remain elevated out of the south to southeast this afternoon, 10 to 15 knots with periodic gusts of 20 to 25 knots. Winds will shift towards the southwest behind a cold front later tonight, 10 to 12 knots. Periodic southwest gusts of 20 to 22 knots will return late Thursday morning and afternoon.

Outlook...Non-VFR likely with a cold front and rain showers Friday through Saturday.

MARINE

S winds of 15-20 knots on Lake Erie will turn WSW behind a weak cold front tonight. WSW winds will then increase to 15-25 knots Thursday morning and continue through the day, so issued Small Craft Advisories for the entire lake. See those products for details. WSW winds will decrease to 10-15 knots Thursday night, turning WNW at 15-20 knots behind a cold front Friday. We will have to monitor for Small Craft conditions again Friday night and Saturday when WNW to NW winds may average 15-25 knots, leading to 3 to 5 foot waves.

Winds will gradually decrease Saturday night and Sunday, but another period of stronger W winds is possible late Sunday into Monday as another cold front brushes the region, so the active time of year has finally arrived.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...Small Craft Advisory from 10 AM to 4 PM EST Thursday for LEZ142. Small Craft Advisory from 10 AM to 7 PM EST Thursday for LEZ143>145. Small Craft Advisory from 7 AM to 7 PM EST Thursday for LEZ146>148. Small Craft Advisory from 10 AM to 10 PM EST Thursday for LEZ149.