textproduct: Cleveland

WHAT HAS CHANGED

Severe thunderstorms remain a concern, especially overnight tonight. Our wind gust forecast continues to trend upward for Friday's potent clipper-type low pressure system.

KEY MESSAGES

1.) Periods of active weather are expected through Wednesday night. This includes the potential for severe thunderstorms, especially tonight into Wednesday, and isolated flash flooding.

2.) Variable temperatures and additional periods of unsettled weather are expected this Thursday through next week Tuesday. This includes the expectation for at least advisory-criteria wind gusts on Friday.

DISCUSSION

KEY MESSAGE #1:

Cyclonic SW'erly to W'erly flow aloft and embedded shortwave disturbances affect our region through Wednesday night as a primary mid/upper-level trough deepens and approaches our region from the west. On the synoptic-scale and at the surface, a strong and wavy front extended generally NE'ward from the southwestern Great Lakes and across southern Lower MI and southern ON to near the border between QC and NY/VT/NH early this afternoon. This front is expected to waver in the same general area through tonight as multiple, weak lows move NE'ward along the front. On Wednesday through Wednesday night, a stronger low is still expected to deepen as it tracks NE'ward along the front, from the southwestern Great Lakes to southern QC. This evolution of the low should allow the trailing and strong cold front to sweep SE'ward across our region late Wednesday afternoon through the evening. Behind the front, a surface ridge builds from the north-central United States through daybreak Thursday. Net low-level WAA in the warm sector will contribute to overnight lows reaching mainly the 50's to lower 60's overnight tonight; well-above average for this time of year. Afternoon highs should reach mainly the upper 60's to lower 70's on Wednesday, ahead of the cold front. Near-record warm highs are forecast. Strong low- level CAA behind the cold front will contribute to lows reaching the mid 20's to lower 30's around daybreak Thursday.

Through this evening, isolated and organized showers and thunderstorms amidst moderate to strong effective bulk shear remain possible in northern OH and NW PA due to the following reasons: low- level convergence/moist ascent along a Lake Erie lake breeze front that should advance a few miles inland from the shore from the NE side of Cleveland through Erie County, PA before the lake breeze dissipates early this evening; moist isentropic ascent aloft, ahead of shortwave disturbances, and low-level convergence/moist ascent along surface trough axes accompanying the shortwaves. These lifting mechanisms are expected to release weak to moderate and primarily surface-based MUCAPE over land and elevated MUCAPE over the relatively-cold/stable Lake Erie marine boundary layer. There is a small risk of damaging wind gusts with these organized storms through early evening courtesy of steep low-level lapse rates and moderate DCAPE before the boundary layer over land starts to stabilize via nocturnal cooling. The potential for small to marginally-severe hail should increase through this evening as mid- level lapse rates steepen to near 7C/km to 8C/km as an EML plume overspreads our area from the WSW and allows MUCAPE in the hail growth zone to increase as ambient melting levels remain near 10kft AGL. The potential for severe convective weather through this evening still appears to be non-zero, but minimal.

The predawn hours of Wednesday morning are when we are most- concerned about severe thunderstorms in our CWA. A WSW'erly nocturnal low-level jet (LLJ) of at least 40 to 50 knots, at/near 925 to 850 mb, should form over our region. This LLJ will enhance moist isentropic ascent, including ahead of the shortwave trough axes, and enhance low-level vertical wind shear and primarily surface-based ESRH (i.e. ESRH values should increase to near 150 to 250 meters squared per second squared). Deepening of lows along the surface front should back surface winds somewhat, which should also enhance surface-based ESRH in our CWA. Primarily surface-based MUCAPE should remain weak to moderate in the warm/moist sector and effective bulk shear will remain moderate to strong as tropospheric winds continue to veer and especially strengthen significantly with height. Mid-level lapse rates should remain steep and MUCAPE in the hail growth zone should remain sizable through about daybreak, before the EML plume exits ENE'ward. Accordingly, organized convection that develops upstream of our region late this afternoon and evening should persist generally E'ward across our region as a QLCS and pose the risk of a tornado or two, as mixed layer LCL's remain favorable, and pose the risk of damaging hail up to golf ball- size. Damaging straight-line wind gusts are also a concern because, for example, the QLCS should exhibit a fairly deep/strong cold pool and DCIN should be limited as synoptic-scale low-level warm/moist air advection persists in the pre-storm environment and limits nocturnal cooling.

During the day on Wednesday, effective bulk shear is expected to remain moderate to strong as tropospheric winds continue to veer and especially strengthen with height. Primarily surface-based ESRH and MUCAPE, respectively, are forecast in the warm/moist sector, especially given the expectation of peeks of sunshine and daytime heating. ESRH should remain sizable as the aforementioned stronger and deeper surface low should cause surface winds to back somewhat and help enhance low-level vertical wind shear. Mid-level lapse rates should be paltry, though, due to the lack of an EML plume. The biggest question for Wednesday's forecast is how much renewed destabilization of the warm/moist sector boundary layer will occur in our CWA given the expectation of mostly cloudy sky and residual outflow from earlier convection. If sufficient daytime heating yields weak to moderate and primarily surface-based MUCAPE amidst steep low-level lapse rates, then another QLCS along the cold front with a threat for tornadoes and damaging straight-line wind gusts would likely materialize. We will continue to monitor this potential closely. Otherwise, if MUCAPE remains paltry, the cold front passage would likely be accompanied by isolated to scattered showers and sub-severe storms. Note: showers and storms are expected to produce periods of heavy rain as the low-level warm/moist air advection from the Gulf yields near-record high PWAT values in the warm sector. Training convection is expected along the front and along the axis of tonight's WSW'erly LLJ as mean mid-level flow exhibits a large component parallel to the front and the LLJ's major axis. Excessive rainfall and localized flash flooding are not out of the question. Once the cold front sweeps SE'ward through our region, rain may mix with and then change to wet snow via nocturnal cooling, the wet-bulb effect, and strong CAA at the surface and aloft before precip along the upper-reaches of the front exits our region by daybreak Thursday. Any snow accumulations should be less than a half inch.

KEY MESSAGE #2:

Dry weather and much colder air temperatures are expected in the cold sector on Thursday as the surface ridge continues building E'ward, a primary trough axis aloft sweeps E'ward over our region, and shortwave ridging aloft follows. Daytime highs should reach only the 30's in NW PA and the mid 30's to lower 40's in northern OH. The ridge exits E'ward Thursday night and allows a warm front to sweep N'ward through our region as a clipper-type low pressure system approaches from the north-central United States and vicinity. A mix of primarily rain and snow is possible via moist isentropic ascent along the upper-reaches of the warm front. Lows should reach the mid 20's to mid 30's before midnight and be followed by moderating temperatures as WAA strengthens at the surface and aloft ahead of and especially behind the surface warm front. As the clipper moves E'ward across the northern Great Lakes region on Friday, the trailing cold front sweeps E'ward across our region. Rain showers along the surface cold front may be followed by a rain/snow mix associated with the upper-reaches of the cold front as cold air deepens behind the surface front. Daytime highs are expected to reach mainly the 40's to lower 50's ahead of the cold front. A strong low-level wind field is expected to accompany the clipper. At least advisory-criteria peak wind gusts (46 to 57 mph) are possible due to the following: diurnal convective mixing of the boundary layer tapping into stronger flow aloft; deep mechanical mixing of the boundary layer tapping into stronger flow aloft for several hours behind the cold front as low-level winds/CAA strengthening with height promote steep low-level lapse rates. Odds favor dry weather Friday night as a ridge at the surface and aloft moves E'ward through our region. Lows should reach the 20's to lower 30's amidst low-level CAA behind the cold front.

Primarily SW'erly to W'erly flow aloft and embedded trough axes should impact our region this weekend through Tuesday. At the surface, our region should mainly be located in the cold sector, but a warm front should sweep N'ward through our region Saturday night into Sunday and be followed by the E'ward passage of a strong cold front later Sunday into Sunday night. Additional periods of rain and/or snow are expected courtesy of the front passages and moist isentropic ascent ahead of the trough axes aloft. Mainly near or below-average air temperatures are expected. For example, our latest forecast calls for highs to reach only the lower to mid 30's on Monday and only the mid 20's to lower 30's on Tuesday. However, above-average high temperatures are forecast in the warm sector on Sunday. Note: a primarily W'erly to NW'erly mean low-level flow of sufficiently-cold/moist air over/downwind of ~3C Lake Erie may generate lake-effect snow Monday into Tuesday.

AVIATION /18Z Tuesday THROUGH Sunday/

Primarily MVFR conditions are in place across the area with mostly cloudy skies. Scattered showers are ongoing across NW Pennsylvania at 18Z where a boundary resides along the Lake Erie shoreline. Scattered showers with isolated thunderstorms are possible at ERI through 20Z. CLE/YNG could experience a light shower but not enough confidence in occurring at the terminal to include through 00Z.

The main feature to watch overnight will be a larger cluster of thunderstorms approaching from southern Michigan and northern Indiana after 06Z. These thunderstorms are likely to produce heavy rainfall, with strong to possibly severe thunderstorms. Winds gusts of 30-40 knots are most likely but 50 knots are possible along with small hail. Storms are expected to be strongest towards TOL/FDY after 07Z but overall probability is fairly low given the late night timing. With that said, brought a period of rain with a 2-3 hour tempo into most terminals starting as early as 07Z at TOL and 12Z at ERI. Winds have shifted out of the north with the showers at ERI at 18Z while all other terminals have southwesterly winds near 10 knots and gusts to 20 knots this afternoon. Overnight showers and thunderstorms will have an impact on winds on Wednesday but breezy southwesterly winds are likely to develop during the afternoon, with a wind shift arriving in the 20-00Z window.

Outlook...Non-VFR likely with showers and thunderstorms Tuesday night into Wednesday followed by rain briefly transitioning to snow Wednesday night into Thursday. Non-VFR may return in scattered rain/snow showers on Friday. Confidence is increasing for widespread strong west to southwest winds on Friday.

MARINE

A stationary front will reside across Lake Erie tonight with potential for showers and thunderstorms producing heavy rain. The thunderstorms may have an impact on the winds on Wednesday but a warm front will try to lift north and enable southwest winds to increase to near 20 knots, becoming westerly to 25 knots Wednesday night with the passage of a cold front. Small Craft Advisories have resumed and will likely be needed Wednesday night.

A ridge builds east across Lake Erie on Thursday with improving conditions. Another very strong low pressure system will track through the Upper Great Lakes on Friday. A strong low level jet will be over the lake on Friday and could see gale conditions both ahead of and with the cold front that arrives Friday night. The track and strength of this system will continue to be monitored over the coming days. The strong southwest to westerly winds could also result in low water conditions on the western basin of Lake Erie. A high pressure ridge quickly builds in on Saturday with improving conditions.

CLIMATE

Daily high temperatures are forecast to approach records through March 11th. Here are the record warm high temperatures at area climate sites for March 10th and 11th.

Date Toledo Mansfield Cleveland Akron Youngstown Erie 03-10 72(2021) 72(1973) 72(1973) 73(1973) 69(2021) 72(2021) 03-11 76(1990) 72(1990) 73(1977) 72(1977) 70(1977) 72(2021)

CLE WATCHES/WARNINGS/ADVISORIES

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