textproduct: Cleveland

WHAT HAS CHANGED

No major changes to the forecast with this update.

KEY MESSAGES

1) Rain exits this evening giving way to a cold night and cool but sunny Saturday.

2) Temperatures warm to well above normal Sunday through next week with periods of showers and thunderstorms.

DISCUSSION

KEY MESSAGE 1... Widespread light rain is progressing slowly east and southeastward across the region this afternoon along a cold front. This rain is being enhanced by frontogenetic forcing beneath the right entrance of a 95-105 knot H3 jet streak over Lower Michigan and SW Ontario rounding the base of a shortwave trough. As this front drops southeast of the region this evening and settles into the Ohio Valley tonight, strong Canadian high pressure at the surface building into the central Great Lakes will quickly advect drier air into the region, so expect a quick end to the rain behind the front. The back edge of the rain should be near the OH/PA border by 23Z, and any leftover showers in far eastern Ohio and western PA will be done by 03Z.

A chilly night in on tap as the high builds in from the north, but northerly flow across the lake will keep lake-effect clouds in place, so this will keep temps from really bottoming out. Expect lows to fall into the 35-40 F range. Lake-effect clouds will clear out by late Saturday morning as the high builds overhead, so expect mostly sunny skies through the afternoon. Even so, temperatures will be much cooler, with highs in the upper 40s to mid 50s. The coolest temps will be near the lakeshore given NE flow off the cold Lake Erie.

KEY MESSAGE 2... A major pattern change is still on schedule to begin Sunday, bringing well above normal temperatures that will last all of next week, as well as active weather in the form of periodic showers and thunderstorms. Confidence is high that temperatures will be a solid 10-15 degrees above normal Sunday through Friday, but timing the individual rounds of showers and thunderstorms remains low confidence.

A lead mid/upper shortwave trough will eject from the Desert SW Sunday morning into the central Great Lakes by Monday morning while weakening and attempting to phase with the northern stream jet. This will result in a weakening surface low lifting toward northern Ontario Monday morning, dragging a cold front through our region during the day. This should lead to decent coverage of showers and thunderstorms late Sunday night into Monday, but early day timing should temper any severe weather threat Monday. Afterwards, a strong mid/upper low moving inland from California Monday will gradually move into the Plains by Wednesday while opening up into a trough that ejects across the Great Lakes while weakening by Thursday. This will strengthen deep SW flow and resultant warm/moist advection Tuesday and Wednesday, so expect the front to quickly return north as a warm front Tuesday. The strongest forcing for convection looks to be out toward the Plains and Mid Mississippi Valley Tuesday and Wednesday, but weak shortwave impulses ejecting out of the main trough in the deep SW flow combined with the broad and unstable warm sector will lead to scattered convection each day. Peak coverage should be in the afternoon and evening hours. It is possible that more of an organized convective system could move in from the west Tuesday night, so the SWODY5 has a risk for severe weather in the far western counties, but confidence is low since this system would likely be weakening overnight. If organized convection occurs next week, Thursday may have the best potential as the shearing out trough described above ejects across the Great Lakes and pushes a cold front into the area. Even so, continued SW flow from renewed mid/upper troughing developing over the western CONUS at the end of next week will keep warm and unstable conditions and additional thunderstorm potential in place Friday. Overall, a warm and active week.

AVIATION /18Z Friday THROUGH Wednesday/

Line of showers moving through the region with ceilings down to MVFR/IFR levels with brief restrictions in rain as well. Low ceilings begin to scatter out 00-06Z, and then give way to mainly high clouds only through 18Z Saturday. This is in response to a cold front moving through, which will have winds westerly gusting 20-30kts turning northeasterly Saturday around 10kts.

Outlook...Occasional non-VFR conditions are expected in periodic showers and thunderstorms Sunday night through Tuesday.

MARINE

Winds now onshore 10-15kts bring wave heights 1-3ft tonight and early Saturday before becoming variable, than southeasterly late Saturday around 10kts. Winds then turns southwesterly Sunday increasing to 10-20kts, then 20-30kts Sunday night and wave heights increasing rapidly away from shore into the open water zones. May need a Small CRaft Advisory early next week due to the offshore winds. Winds remain southwesterly 15-25kts through Wednesday.

CLE WATCHES/WARNINGS/ADVISORIES

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