textproduct: Cleveland

WHAT HAS CHANGED

The evolution of MCS development tonight and how it will translate through the day today and later tonight will continue to be in flux.

KEY MESSAGES

1) Rounds of convection possible today and tonight, hinging on the initial systems this morning.

2) Cooler airmass and high pressure into the end of the week.

DISCUSSION

KEY MESSAGE 1... All eyes this morning will be on the developing thunderstorm complexes currently in northern Minnesota and over eastern Lake Superior. Evolution has been slow thus far and IR imagery showing cloud top cooling is minimal at this point although growing in size over Whitefish Bay, and expect enhancement over the next few hours. Bulk shear vectors will take these developing complexes southeastward into the southern Great Lakes, where CAMs/rapid update models have had a hard time providing any consistency to their solutions on where MCSs will go and if/when they decay. As they move towards the Cleveland CWA, plenty of elevated instability to work with, but atmospheric layer above the boundary layer needs some work in terms of RH as it is pretty dry for the time being. Outside of the drier layer of air aloft, surface dewpoints in the mid 60s and usable mid level lapse rates exist. However, the timing of the MCS works against it for our area as it tracks southeastward towards dawn, and will likely suffer decay as cloud tops are forced to warm with minimal low level jet energy in place. That said, there is an expectation of a few lingering clusters of showers or showers with isolated thunder this morning from the Lake Superior MCS. Further west, the Minnesota system is one that hi res models and CAMs are suggesting will survive into the daytime, and could affect our CWA later today. Ultimately, the forecast challenge here is that the rest of the day and into the overnight is likely going to rely on what happens with these initial systems, how long it takes or if the atmosphere needs to recover from them, if there are lingering wake MCVs, etc. Expect an evolving forecast, but know that the chances for convective activity will exist from this afternoon into the overnight hours.

KEY MESSAGE 2... A cold front will come through Tuesday morning with a wholesale airmass change with cooler and drier air in place. Additional upper trough axes will swing through the CWA north to south, and the onshore flow coupled with this could generate showers with some lake enhancement as the 850mb temperatures drop into the lower teens. High pressure will then settle into the southern Great Lakes for the end of the week with temperatures in the mid 70s to lower 80s through Thursday.

AVIATION /12Z Monday THROUGH Friday/

Areas of MVFR BR in patchy fog this morning across inland terminals. Terminals with MVFR visibility should lift to VFR within the next 1-2 hours. Have a few TEMPO groups in the TAF sites to account for BR through 13Z/Mon.

Looking upstream the possibility of showers and thunderstorms at western terminals this morning has significantly decreased and have removed any TS mention at KTOL/KFDY for this morning. Looking ahead, there remains a large model spread between hi- res members for additional rounds of showers and thunderstorms across the Great Lakes and Ohio Valley region during this afternoon into the evening/overnight. One possible outcome would be for the convection currently diving south across Lake Superior to enter terminals ~20z/Mon. This cluster is progged to dive southeast across terminals through ~03Z/Tue. Will need to continue to monitor the progression of this complex as it sinks southeast during the day today. Given confidence levels, have PROB30 this evening at all terminals for any TS impacts.

Southwesterly winds 7-10 knots with isolated 10-12 knots across western terminals today. Southerly winds 8-12 knots this evening slowly shift northerly overnight tonight into Tuesday morning.

Outlook...Non-VFR possible with periodic showers and thunderstorms this morning through Tuesday.

MARINE

Light winds will increase to southwest winds 8-12 knots this morning. Winds will shift southerly and gradually increase to 15-20 knots this evening before eventually turning northerly at 20-25 knots by Tuesday morning. Northerly winds continue through Wednesday. Given elevated onshore flow wave heights are expected to build to 3-6 feet both Tuesday and Wednesday. Will likely need Small Craft Advisories and Beach Hazard Statements for this timeframe. High pressure will approach from the west allowing for northerly winds 15-25 knots to diminish to 10-15 knots by Thursday morning before winds become light and variable on Friday.

A series of weakening thunderstorm complexes moving in the vicinity of Lake Erie remain possible through tonight. Winds and waves may be locally higher in any thunderstorm that does move over the lake.

CLE WATCHES/WARNINGS/ADVISORIES

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