textproduct: Cleveland

WHAT HAS CHANGED

Some minor timing adjustments for the convection today, and a slight increase in low end POP coverage prior to the main line with the cold front late this evening into tonight.

KEY MESSAGES

1) A lingering stationary front followed by a cold front brings shower and storm chances to the CWA later today and into tonight.

2) High pressure this weekend followed by another low pressure system/cold front Monday night through Tuesday which brings the next chances for showers and storms.

DISCUSSION

KEY MESSAGE 1... A stationary front will linger over far NE OH/NW PA today as low pressure and a cold front move in from the northwest. Warm sector dewpoints in the 50s today with temperatures in the upper 70s to lower 80s areawide equates to marginal instability but still enough for a convective threat today. Impeding the threat to some degree will be a decaying low level jet as the system approaches and sharp upper level ridging. For the afternoon hours, there will be a modest amount of elevated CAPE along with the troughing at the surface which could result in some afternoon convection, but the main limiting factor is the amount of dry air in the column rising air would have to overcome. This is a low threat overall through the afternoon hours, but not zero, and have a large coverage of slight chance POPs during this time frame. The main batch of convection will be later in the evening when the flow aloft abruptly turns southwesterly and some upper level support finally comes into the mix. However, as mentioned previously, the lower level dynamics will be phasing out, and only a sliver of the low level jet will remain, around 30-35kts. With just enough 0-6km bulk shear around 25-30kts and column RH increasing, some organized convection with a wind threat is possible. This wind threat may be most likely to occur at the onset later this evening as inverted V soundings will dominate the boundary layer structure prior to the saturating in precipitation. Some POPs linger into Saturday without a thunder threat with the exiting of the low pressure system. Temperatures fall off 10-20 degrees from Friday to Saturday.

KEY MESSAGE 2... High pressure builds through the weekend with the cooler temperatures, rebounding again Monday ahead of the next low pressure system. Upper level ridging returns Monday, and this is when the warm air advection will really begin to take hold again. Temperatures back into the upper 60s to mid 70s for Monday, and low pressure moving in from southwest for late Monday into Monday night. This is the next convective chance for the CWA with possibly better organization as it looks to be a stronger overall surface system, but these details will come out in subsequent forecasts. Temperatures drop for the middle/end of the week in what could be an extended period of normal to slightly cooler than normal weather.

AVIATION /12Z Friday THROUGH Tuesday/

Widespread VFR conditions are expected to continue for much of today ahead of a cold front that will impact the area this evening. Showers and storms associated with this boundary should begin to impact western terminals near 20Z before spreading east. There is higher confidence in thunder potential further west, however opted to put in at least vcts at most terminals into the overnight hours. Diminished visibilities are possible, especially within the strongest storms, but should rebound to VFR. Conditions will begin to decline post front as CAA pushes over the area and both ceilings and visibilities begin diminish to at least MVFR conditions with patchy fog possible at terminals where precipitation has ended.

Winds tonight will be light and variable before increasing to 5-10 knots from the southwest this afternoon. The exception will be KCLE and KERI which have the potential to be impacted by a light lake breeze. Confidence is not as high at KCLE compared to KERI, but given the late timing of the front, it is possible. Behind the boundary winds will remain 5-10 knots but shift to northwesterly.

Outlook...Periodic showers and thunderstorms with non-VFR possible this afternoon through Saturday morning and again on Monday.

MARINE

East to northeast winds of 5-10 knots will impact Lake Erie today, allowing waves to build to 1-2 feet across the central and western basins. A cold front will push east this evening into the overnight hour, allowing for winds to gain a more northerly component but remains 5-10 knots. These conditions are expected to persist through the weekend before winds ramp up in association with a strong low pressure system that moves through the western Great Lakes region for the start of next week. Winds look to increase to 15-20 knots for a period of time late Monday into Tuesday, which may need a Small Craft Advisory.

CLE WATCHES/WARNINGS/ADVISORIES

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