Marine Weather and Tide Forecast for West Homestead, PA

KEY MESSAGES
1) Rain changes to snow later this afternoon/evening. Much colder with snow showers Tuesday. Winter Weather Advisory for the higher terrain.

2) Milder conditions later this week

DISCUSSION
KEY MESSAGE 1...

A strong cold front is crossing the area this afternoon, with temperatures already plummeting behind the front. Rain will mix with and change to snow later this afternoon as 850mb temperatures quickly drop to around -10 deg C by this evening. A secondary wave tracking NE through the upper level flow will also bring an enhancement to the snow through the late afternoon and evening hours. While ground temperatures remain warm, snowfall rates of 0.5 to 1.0 in/hr roughly between 6-10pm this evening should be enough to overcome this, producing at least a coating in most places. This could create slick spots during the evening commute though accumulation will be maximized on elevated surfaces.

Additional snow showers are expected into the overnight and Tuesday as an upper level trough crosses the region, and terrain/lake enhancement occurs in wrly flow. Soundings indicate favorable moisture and lapse rates in the dendritic growth zone for accumulating snowfall, especially in the ridges. Snow squall parameter also maxes out around 6-7 units Tuesday morning, indicating we could see squalls through the morning and early afternoon. These would produce localized enhancements of snow totals.

Snowfall amounts trended up again with the 12z cycle, with probabilities for at least an inch of snow reaching 75 percent or greater across northern WV, and wrn PA. Those probabilities decrease farther west. Interquartile ranges for the same area generally range from 2-4 inches, and it is expected some may see a localized 3+ inches under snow bands through Tuesday.
Probabilities for at least three inches are highest north of I-80 and in the ridges. With upward trends and better confidence in earlier accumulation this evening, have expanded the Winter Weather Advisory across the I-80 corridor and all of the ridges through Tuesday. Highest amounts are expected across Tucker county, WV, where ridgetops may exceed 6 inches.

Snow showers should begin to taper off later Tuesday afternoon/Tuesday evening as surface high pressure begins to build across the region. Much colder temperatures are also expected through the period, with highs generally only 25 to 30 deg on Tuesday.

KEY MESSAGE 2...

While the area is expected to remain under NW flow aloft, gradually rising 500 mb heights should result in a gradual warming trend through the end of the week. Individual shortwave embedded in the flow will bring periodic, mainly rain, chances to the region from mid to late week.

AVIATION /18Z MONDAY THROUGH SATURDAY/
The front will have moved east of the forecast area this afternoon as the showers are expected to change over to snow showers as the colder air infiltrates the forecast area. Expect VFR and MVFR conditions to deteriorate to IFR and below as the evening goes on with snow showers and cigs dropping below 1 KFT in some terminals.

Intermittent conditions with the snow showers through the overnight will feature times with LIFR conditions before becoming MVFR towards the end of the TAF period. Heading into the day tomorrow, some additional snow showers will be possible that will drop conditions from time to time. Winds are expected to be W to WNW with gusts reaching 30 knots at times.

Outlook...Dry and mainly VFR weather is expected Wednesday.
A weakening disturbance will likely weaken upstream in the Ohio Valley with clouds but the snow with the system will struggle to make it into upper Ohio River valley Wednesday night. Light precipitation changes and perhaps restrictions are possible Thursday and Friday but precipitation would likely fall as rain if it does occur.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...Winter Weather Advisory from 5 PM this afternoon to 5 PM EDT Tuesday for PAZ007>009-015-016-074-076>078.
OH...None.
WV...Winter Weather Advisory from 5 PM this afternoon to 5 PM EDT Tuesday for WVZ510>514.
Wind Advisory until 2 AM EDT Tuesday for WVZ514.