897 FXUS61 KCLE 060114 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 914 PM EDT Sun Jul 5 2020 .SYNOPSIS... High pressure will persist over the area through midweek with continued hot temperatures. A weak trough will move over the region from the northwest Tuesday night into Wednesday. Rain chances will increase from mid to late week as the airmass becomes more humid. A cold front will move into the area on Friday. && .NEAR TERM /THROUGH MONDAY NIGHT/... No major changes to the forecast at this time. Low temperatures are expected to fall into 60s overnight with mostly clear conditions. Previous Discussion... Persistent high pressure is the focus for the near term forecast as it remains centered over the central Great lakes. The airmass over the area has dried marginally and dewpoints this afternoon dropped to the mid 50s with PWATs around 0.75". Higher moisture remains just on the periphery of the area and will start to encroach into the area overnight with dewpoints rising into the lower 60s. Min temperatures tonight will be in the mid 60s as a result. Could see some redevelopment of haze late tonight/early Monday but with cross over temperatures in the mid 50s believe our min Temps tonight won't be cold enough to support any fog despite moisture advection. With a warmer start to the day, expect temperatures to reach a few degrees warmer than today's highs with much of the area reaching into the 90s. Still anticipate a lake breeze development in the afternoon. A few factors have made me put a slight chance of isolated tsra into the forecast for tomorrow. We will see nw flow at 500mb which will marginally lower mid level temps, and an increase in PWATs to around 1.4". For anything to get going there will need to be a focusing mechanism to pool some moisture in order to support cloud and rain development, like the lakebreeze. With moisture profiles best in the NW have put the isol chances in this area, however could see some on the periphery of our southwestern counties like Marion, Wyandot, Hancock. The instability will not be a limitation, however the shear profiles are poor and insufficient for any organized storms. So essentially can't rule out a chance for a few pop up thunderstorms, mainly west. Any development will be short lived and gone by evening. Should the ridge remain stronger than anticipated it could be another dry afternoon with hardly a cloud visible. Going into Tuesday an approaching weak/decaying short wave topping the ridge in combination with a light synoptic surface wind flow (which should allow lake breezes to form) may be the catalyst needed to finally spark at least a few showers or storms during peak heating (early to mid afternoon on into the early evening hours). Do not expect much more than isolated to scattered coverage. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... A shortwave trough aloft will enter the Great Lakes region on Tuesday and flatten the upper ridge that has been over area for the last several days. Ahead of this feature, low level moisture will increase over the area, allowing for a greater potential - albeit still widely scattered - for shower and thunderstorm activity with the diurnal cycle and off any lake breeze that may develop. Temperatures will remain hot as 850 mb temperatures of 20 to 22 C will mix down to the surface. This, along with the increase in moisture, will allow for heat indices to be on the rise into the mid to upper 90s on Tuesday. Some leftover cloud cover overnight could keep the area warmer well into the 70s for Tuesday night. The surface trough enters on Wednesday and will allow for slightly better shower/storm chances across the area. The warmer start to the morning plus increasing low level moisture may allow for temperatures and heat indices to creep a degree or two higher on Wednesday. Some locations could see heat indices exceed the 100 degree mark and Wednesday will need to be monitored for a possible heat advisory. && .LONG TERM /THURSDAY THROUGH SUNDAY/... The upper ridge will reestablish itself over the area on Thursday and the prolonged period of above normal temperatures will continue with highs in the low to mid 90s. Rain chances appear diminished on Thursday with warmer, capping air returning to the region. However, the heat and humidity are still around to allow for high indices to continue to be a concern. A more robust shortwave trough will enter the Great Lakes region for Friday into the weekend. This system will allow for modest heat relief for the weekend and while bringing more unsettled weather to the area. && .AVIATION /00Z Monday THROUGH Friday/... VFR conditions are expected through the entire TAF period as the region remains under the influence of high pressure and a strong upper ridge. Most of the diurnal clouds have dissipated this evening and conditions should be clear for tonight. Will maintain the TAFs without any haze/mist over the overnight, but KCAK and KYNG could be candidates for some brief restrictions in the pre-dawn hours with clouds currently in the area and some better dew points. But, since confidence is low given how much drier we are this evening than last evening, will keep the forecast VFR. No aviation weather concerns for Monday afternoon other than some patches of diurnal clouds are possible. Winds will be light and variable over the region with a stronger northerly wind off the lake for KERI and KCLE for Monday. Outlook...Non-VFR in isolated thunderstorms on Tuesday and scattered thunderstorms on Wednesday and Friday. && .MARINE... The marine weather remains extremely quiet for the first full week of July. Light and variable winds will continue through the next couple of days with high pressure near the area. A weak surface trough will approach the area on Wednesday, encouraging more southerly, offshore flow over the lake. High pressure returns on Thursday to allow for more light and variable flow to return to the area. A cold front will approach for Friday into the weekend and bring the next chance for any notable wind change. Diurnally-driven shower and thunderstorm activity is possible on Tuesday through Thursday with the best chance on Wednesday at this time. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Jamison NEAR TERM...Jamison/Sefcovic SHORT TERM...Sefcovic LONG TERM...Sefcovic AVIATION...Sefcovic MARINE...Sefcovic