textproduct: Cleveland

WHAT HAS CHANGED

Chances for light rain showers Wednesday have increased, especially south of a Findlay, OH to Meadville, PA line.

KEY MESSAGES

1) Light showers are expected late tonight and Wednesday, especially south of a Findlay, OH to Meadville, PA line. The lakeshore counties will probably not see any rain.

2) Dry and very pleasant weather expected Thursday through early next week.

DISCUSSION

KEY MESSAGE 1... The only opportunity for rain over the next 7 days (and likely beyond) will be late tonight and Wednesday as weak low pressure traverses an old frontal boundary. The boundary is currently draped over the Tennessee Valley, and moisture advection and isentropic ascent is driving a band of showers north of this boundary along and north of the Ohio River. Clouds will increase from south to north this evening and tonight, and as the surface low moves out of the Mid Mississippi Valley and into the Lower Ohio Valley late tonight, the warm/moist advection and isentropic ascent will strengthen and lift the boundary slightly farther north by Wednesday morning. This combined with a 60-70 knot H3 jet associated with the mid/upper shortwave will bring showers into the region. The latest HREF, RAP, and NAM are in general agreement on a band of showers setting up along and south of a roughly Findlay to Meadville line in the 09-16Z timeframe before shifting southeastward through the afternoon as the mid/upper shortwave and associated surface low depart. Increased POPS to likely/categorical in much of this swath late tonight through early Wednesday afternoon, with some chance POPS farther north, although the lakeshore counties will probably not see any rain.

A northern stream cold front will drop across the region Wednesday night and overtake the old frontal boundary, with strong Canadian high pressure then building down across the Great Lakes Thursday through the weekend leading to cool, dry N to NE flow.

KEY MESSAGE 2... As mentioned above, a long stretch of dry and pleasant weather that sets in Thursday will likely persist beyond the next 7 days. As the aforementioned Canadian high at the surface builds across the Great Lakes Thursday through the weekend, it will be held largely in place by an Omega Block in the mid and upper levels. Lingering mid/upper troughing over the NE CONUS will evolve into a large closed low by early next week while a series of mid/upper troughs and closed lows rotate through the Rockies. This will pinch off a large mid/upper ridge in between across the northern Plains and central Canada. This block will also be reinforced by southern stream troughing in the deep South. The Great Lakes and Ohio Valley regions will remain on the dry side of the Omega Block, with upper level confluence and surface high pressure across the lakes supporting mostly sunny skies and cool N to NE flow Thursday well into next week. This will keep high temps mostly in the low/mid 70s, with low temps in the upper 40s/low 50s.

AVIATION /18Z Tuesday THROUGH Sunday/

SW'erly to NW'erly flow aloft and embedded disturbances impact northern OH and NW PA through 18Z/Wed. At the surface, a high pressure ridge exits slowly SE'ward as a weak cold front approaches from the northern Great Lakes and reaches southern Lower MI and the northern shore of Lake Erie by 18Z/Wed. Our regional surface winds trend mainly light and variable through the TAF period. However, a lake breeze of about 5 to 10 knots is expected over and within several miles of Lake Erie until ~23Z/Tues and after ~16Z/Wed. This lake breeze is expected to impact KCLE and KERI.

Primarily VFR and variable amounts of low/mid/upper-level cloudiness are expected through the TAF period. However, moist ascent ahead of the axis of one of the disturbances aloft should allow rain showers, steady to heavy at times, to overspread our region from the south and west after ~06Z/Wed and persist through 18Z/Wed, especially roughly along and south of a line through KYNG and KFDY. Periodic MVFR may accompany showers. A few thunderstorms are possible, but confidence in a thunderstorm impacting any TAF site is low.

Note: areas of mist and/or fog may form via nocturnal cooling amidst sufficient low-level moisture after ~05Z/Wed before dissipating soon after daybreak Wed. However, odds favor abundant cloud cover preventing mist and/or fog formation.

Outlook...Scattered rain showers and isolated thunderstorms with non-VFR are possible Wednesday afternoon through evening. Current odds favor dry weather and VFR this Thursday through Sunday.

MARINE

A high pressure ridge exits slowly SE'ward before a weak cold front sweeps generally S'ward across Lake Erie late Wednesday afternoon through evening. Variable winds around 5 to 10 knots ahead of the cold front become N'erly to NE'erly around 5 to 15 knots behind the front as a high pressure ridge begins to build from the Hudson Bay area. This ridge should continue to build generally from the north on Thursday through this Sunday and be accompanied by mainly NW'erly to NE'erly winds around 5 to 15 knots. Waves are expected to be 3 feet or less the rest of this week through Sunday.

CLE WATCHES/WARNINGS/ADVISORIES

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