Marine Weather and Tide Forecast for Indiana, PA

KEY MESSAGES
1) Fog today, with waves of rain continuing through tonight.
Some potential for strong storms mainly south of I-70 this afternoon

2) Severe thunderstorms possible Saturday

3) Record or near record highs Saturday

DISCUSSION
KEY MESSAGE 1...

A quasi stationary surface front was analyzed from western Ohio into northern West Virginia early this morning. Rain will continue to overspread the region through early morning as a shortwave tracks ENE along the front. Overall rainfall rates have decreased over the past couple of hours, with satellite imagery also showing warming cloud tops. A few embedded thunderstorms were also occuring with some weak elevated instability (Showalter index 0 to -1.) QPF is expected to be the greatest across SE OH and nrn WV, with generally a third to three quarters of an inch through the morning. Fog will continue, and where most of the rain has ended visibilities have dropped to a quarter of a mile or less in many locations. Issued a Dense Fog Advisory for these areas, and will monitor further trends.

The surface boundary is expected to lift northward through the day as the flow aloft backs to the SW ahead of an approaching shortwave trough. This trough, and an associated surface low tracking along the front, is expected to cross the Upper Ohio Valley region this afternoon and evening, maintaining waves of rain across the area. The heaviest QPF shifts north of PIT this afternoon, closer to the surface boundary, where flash flood guidance values are high and no significant flood potential is expected.

The surface low is progged to track across west central and northwest PA late this afternoon and evening. There is some potential for thunderstorms to develop along the boundary SW of the low across SE OH/nrn WV/far SW PA, where 0-6km shear increases to 40-50kt this afternoon. Thunderstorm development will depend on how much instability develops this afternoon, with cloud cover expected to be the main limiting factor.

Rain should decrease tonight as the shortwave and surface low exits the area, and the front drops back to the south. The front will return north on Friday as the upper flow backs to the SW, with lower chances for rain especially in the morning.

KEY MESSAGE 2...

Southwest flow is expected on Saturday, as a more amplified shortwave and associated surface cold front approach from the Midwest. 40 to 50 kt of 0-6km shear is expected to develop through the afternoon ahead of the front, as ensemble progged MLCAPE approaches 500 j/kg. The instability will be affected by the amount of clearing and surface heating that occurs, though at this time it appears there is the potential for strong to severe storms as FROPA occurs late in the day. It appears the main hazard would be damaging winds. The Storm Prediction Center has included the region in a Slight Risk for severe thunderstorms.

KEY MESSAGE 3...

Record or near record highs are possible on Saturday. Here are the records for stations around the area for March 7th.

Record...... Forecast High KPIT: 76/1983 75 KDUJ: 64/2016 68 KHLG: 74/2009 75 KPHD: 75/2000 74 KZZV: 77/2009,1983 75 KMGW: 79/1995,1983 77

AVIATION /08Z THURSDAY THROUGH MONDAY/
Showers and a few rumbles of thunder associated with mid- level shortwave energy is arriving from the west, traveling along the wavering boundary. ZZV is likely the only terminal to see thunder. This swath of rain will saturate the lower levels, leading once again to LIFR ceilings at most terminals.
Visibility will generally be in the IFR range during the heavier rain periods. Dense fog is a little less likely tonight due to better mixing, but is still possible where a strong low-level inversion can develop.

Periods of rain are likely to continue through Thursday, with little improvement to ceilings overall until after 18Z, when the front may bow back northward once again and allow for some ceiling rises near and south of PIT. A thunderstorm or two is not out of the question. However, given the expected thick cloud cover, chances remain quite low and were not included in TAFs at this time. Some terminals will begin to deteriorate in vis and cigs again tomorrow night.

Outlook...
Periodic periods of rain with restrictions are likely through Friday as a quasi-stationary front stalls across the Upper Ohio Valley region. Crossing low pressure will keep rain, and possibly thunderstorms, in the forecast for Saturday. VFR and quieter weather are expected for Sunday and Monday.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...Dense Fog Advisory until 10 AM EST this morning for PAZ020-021- 029.
OH...Dense Fog Advisory until 10 AM EST this morning for OHZ039>041- 048>050-057>059.
WV...Dense Fog Advisory until 10 AM EST this morning for WVZ001>003.