textproduct: Cleveland

WHAT HAS CHANGED

No wholesale changes.

KEY MESSAGES

1) Scattered to numerous thunderstorms are expected across Northwest and North Central Ohio later today, especially between 4 PM and 10 PM. Isolated severe weather is possible, with strong wind gusts and hail up to quarter-sized the main risks.

2) Warmer weather continues through the end of the week. After an isolated rain chance Thursday afternoon, more widespread rain is likely late Friday into early Saturday.

3) More unsettled weather is in the forecast early next week as the next system brings widespread rain and perhaps some thunderstorms to the area late Monday into Tuesday.

DISCUSSION

KEY MESSAGE 1... As of early this afternoon a frontal boundary is draped from near the Ohio-Michigan boarder points east-southeast to just south of Cleveland and over to near Youngstown. A very subtle shortwave and associated weak surface low is located near the Michigan-Indiana boarder and will drift east through this evening. The front itself will likely push a bit farther southwest from its current location over the next several hours, especially west of Lorain as winds turn off the cooler lake.

It is currently mostly sunny, dry, and warm across the area, particularly south of the front. A few thunderstorms are ongoing across northern Indiana/southwestern Michigan closer to the surface low. This activity will gradually spread east-southeast into Northwest and North Central Ohio through this evening as the low and shortwave drift in, with greatest storm coverage expected along and just southwest of the front. Storms are expected to weaken and dissipate tonight as the weak low/shortwave exit and as the atmosphere stabilizes. Storms will likely start spreading into the I-75 corridor by 3 or 4 PM, with activity likely to completely subside by midnight. The northeast half of the area will stay dry on the cooler/stable side of the front.

Modest deep-layer shear (25-30kt) and instability (500-1500 J/KG of MLCAPE) can support moderately intense, somewhat organized convection. Cool/dry air aloft is expected to contribute to 700-900 J/KG of DCAPE, with very steep low-level lapse rates of >9C/km. This combination of factors can support a few strong to marginally severe storms, with downbursts/strong winds the main concern with any more intense cells or small clusters. If we see any more intense or rotating cells, marginally severe hail can't be ruled out either. Any severe threat should subside pretty quickly around/after 8 PM.

Dry weather is then expected overnight with lows ranging from the 40s in far Northeast OH and Northwest PA to the 50s across the rest of the area. With light winds and a fairly humid airmass for April (especially along and southwest of the stalled front) a bit of radiation fog is possible late tonight into early Thursday, though lingering clouds near/southwest of the front lower confidence in fog.

KEY MESSAGE 2... The front we've been talking about in "key message 1" will still be in the picture for Thursday...we'll likely start the day with the front stalled across Northwest and Central OH, with the front expected to begin inching northeast through the afternoon. The front will stall across the lake and near Erie, PA Thursday night. Aside from the front there will be lack of forcing on Thursday as shortwave ridging slides east across the region. Still, daytime heating will contribute to uncapped, weak-moderate (500-1500 J/KG of MLCAPE) instability that may contribute to isolated storm development near the slowly lifting front across parts of Ohio during the afternoon. Overall, Thursday will be a mainly dry and warm day as highs push well into the 70s across much of the area (Erie may stay in the 60s and the I-75 corridor may reach 80). It will be dry and mild Thursday night, with lows mainly in the 50s.

Closed lows will park over the northern Rockies and Canadian Maritimes by Friday, with a shortwave expected to slide east across the local area Friday night into Saturday between the two closed lows. This shortwave will be accompanied by a surface low that will track along the stalled front near Lake Erie Friday night/early Saturday. Rain is expected to spread in from the west late Friday into Friday night with these features, with rain gradually exiting to the east on Saturday. While the trend will be drier from west to east through Saturday, it's worth noting it may end up taking a good portion of the day for our eastern counties to fully dry out. Some thunder is possible late Friday into Friday night, especially across Northwest OH where activity should spread in late Friday afternoon or evening. The concern for severe weather is on the low side. The slower-moving system combined with above average precipitable water values may lead to localized QPF amounts of over an inch Friday into Saturday, though with area-average QPF values currently closer to the 0.40-0.60" range. Overall, am not expecting flooding.

Friday will remain quite warm, with most of the area expected to see highs ranging from the mid 70s to near 80. Highs will cool into the 60s Saturday as a cold front drags through behind the low pressure.

KEY MESSAGE 3... A brief spell of quieter weather is anticipated Saturday night through at least early Monday as high pressure builds into the Great Lakes/New England/southeastern Canada. A fairly potent trough is expected to eject into the Plains to start the week before lifting into the upper Great Lakes. This will drive fairly strong low pressure into the northern Great Lakes Monday night into Tuesday. A warm front is expected to lift through on Monday, followed by a cold front Monday night or Tuesday. Either way, more rainy weather is expected later Monday into Tuesday, along with a brief warm-up on Monday when we get into the warm sector. This will be a more dynamic system capable of producing severe weather and perhaps locally heavy rain, though details such as the timing of the front and amount of available instability are uncertain at this distance, making the potential for any hazardous weather uncertain.

AVIATION /18Z Wednesday THROUGH Monday/

At the surface, a very weak front is located near the southern shore of Lake Erie. This front should waver in a north-south manner between the southern lakeshore and Mid OH through 18Z/Thurs as very weak lows move E'ward along the front. Our regional surface winds trend mainly SW'erly to W'erly around 5 to 10 knots through ~23Z/Wed, but a lake breeze will impact locations along and within several miles of Lake Erie, including KCLE and KERI, through the same time period. After ~23Z/Wed, our regional surface winds trend light and variable. However, another Lake Erie lake breeze is expected to develop after ~15Z/Thurs and impact KCLE and KERI.

Mainly dry weather and VFR are expected through 18Z/Thurs. However, scattered showers and thunderstorms have developed over/near southwestern Lower MI. Scattered showers and thunderstorms are expected to regenerate along the established outflow. Additional, isolated showers and thunderstorms should develop along the Lake Erie lake breeze front in NW OH during this late afternoon through early evening. All of this convection is expected to persist generally SE'ward through ~04Z/Thurs, especially roughly along and southwest of a Toledo to Sandusky to Steubenville line. Brief MVFR to LIFR and brief/erratic wind gusts up to 30 to 50 knots are expected with showers and especially storms.

Mainly clear sky, weak or calm surface winds, and residual low- level moisture from the expected rainfall should permit radiation mist/fog development from ~07Z through ~11Z/Thurs, especially roughly along and southwest of the aforementioned line. Any mist or fog should dissipate by 13Z/Thurs, following the onset of diurnal convective mixing of the boundary layer.

Outlook...Periodic showers and thunderstorms with non-VFR are possible Thursday afternoon through early evening, Friday through Saturday night, and this Monday.

MARINE

A very weak front should waver in a north-south manner between the southern shore of Lake Erie and Mid OH through Friday as very weak lows move generally E'ward along the front and this front is augmented by the Lake Erie lake breeze at times. A lake breeze around 5 to 10 knots through this early evening will gave way to primarily NE'erly to E'erly winds around 5 to 15 knots tonight through Friday as a high pressure ridge attempts to build from northern ON and eventually northern QC. These winds will trend onshore during the late morning through early evening hours of Thursday due to renewed lake breeze development. Waves will be 3 feet or less through sunset Friday evening.

During Friday night through Saturday morning, the aforementioned front should be located near the southern lakeshore. Simultaneously, a somewhat stronger low should move E'ward along the front and cause winds around 5 to 15 knots to back from ENE'erly to N'erly to NW'erly. Behind the low, the front will exit SE'ward as another high pressure ridge builds from the north-central United States through this weekend. Accordingly, NNW'erly winds around 5 to 15 knots should veer gradually to NE'erly to E'erly. On Monday, the ridge should begin to exit E'ward and cause NE'erly to E'erly winds around 5 to 15 knots to veer toward SE'erly and freshen to about 10 to 20 knots. Waves should remain 3 feet or less Friday night through this Monday, but occasional 4 footers are possible in open U.S. waters on Monday.

CLE WATCHES/WARNINGS/ADVISORIES

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