Sunrise 6:34 AM   Sunset 8:03 PM Moonrise 2:05 PM   Moonset 3:32 AM

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FXUS61 KPBZ 182306 AAA AFDPBZ

Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 706 PM EDT Thu Apr 18 2024

SYNOPSIS
Precipitation chances return early tomorrow with a passing front, a few thunderstorms may occur. The potential for frost/freeze impacts increases Sunday and Monday morning.

NEAR TERM /THROUGH FRIDAY/
KEY MESSAGES:

- Overnight low temperatures will trend above average with linger low-lvl moisture and cloud coverage increasing with an approaching disturbance.

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For the evening update...slowed down the onset of the showers just a bit. A t/td spread of close to 30 degrees this evening will make it difficult for anything but sprinkles to reach the ground until surface dewpoints start to rise. 18z model data is showing an increasing surface southeasterly flow, which will continue to support the drier air near the surface.
Additionally, as the shortwave associated with the surface from digs into western Ohio late tonight, minor heights rises are expected over much of the region, increasing subsidence. Rest of the forecast in good shape.

The progression of ridging over western Ohio into western PA this evening will support mainly clear skies this evening.

Clouds will increase overnight amid warm, moist advection ahead of the next shortwave system set to traverse the Ohio River Valley Friday. Therefore, above average temperatures will continue into the overnight hours.

SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
KEY MESSAGES:

- Showers and low probability thunderstorms are expected ahead of a cold front Friday. Lightning will be the main threat.
- Seasonable temperature and dry weather expected through the weekend.
- Potential for frost and/or freeze impacts each of Saturday and Sunday mornings.
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An approaching shortwave and cold front will increase the chances of showers before dawn Friday. There could be a few isolated thunderstorms south of Pittsburgh will elevated instability from lingering dry air from the eroding ridge.
Lightning will likely be the only threat early Friday morning.

The probability of precipitation decreases from west to east with the passage of the cold front late Friday and decreasing low-lvl moisture.

Confidence is high that an elongated trough over the Great Lakes will increase cooler conditions over the weekend. For Saturday and Sunday, temperatures will trend 5 degrees below average.

With cooling temperatures, the potential for early morning frost/freeze conditions Saturday night into Sunday will be elevated in some areas. For our county warning area, all counties but Tucker County are experiencing active vegetation growth. Therefore, frost/freeze products may need to be issued in the 24 to 48 hours.

LONG TERM /MONDAY THROUGH THURSDAY/
KEY MESSAGES:

- A building ridge over the Midwest late Monday will increase the chances of near or above temperatures early next week.
- Next precipitation chances are likely to be Tuesday into Wednesday with crossing low pressure. The confidence in thunderstorms is low.
- Ensembles favor dry conditions outside of that period.
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Dry, quiet weather is anticipated Monday as a ridge, that was over the central CONUS, advances east. Near to above temperatures are expected to return.

Precipitation chances return late Tuesday into Wednesday as a shortwave passes through the Great Lakes region. Trough depth and axis timing remains varied among ensemble members, but they all favor a shower environment with low to limited lightning potential.

Long range ensembles favor ridge building over the western Great Lakes in response to a deepening trough over the western CONUS for the late week period. The expectation is for area temperature to once again rise with any passing shortwave posing greater thunderstorm potential.

AVIATION /23Z THURSDAY THROUGH TUESDAY/
VFR is expected through tonight as shortwave ridging builds across the Upper Ohio Valley region. The ridge will slide east of the area early Friday morning, as a shortwave trough and surface cold front approach from the west. Showers are expected to overspread the region with the approach and passage of the front, along with deteriorating flight conditions to MVFR.

FROPA is expected to occur W-E from late morning through mid afternoon, with a WSHFT from S to WNW. Improvement back to VFR is expected by evening under dry advection and a building surface ridge, though mid level cigs will continue under a broad upper trough.

Outlook
A ridge of high pressure at the surface will maintain VFR conditions through early Tuesday. Showers and potential restrictions return late Tuesday with an approaching cold front.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...None.
OH...None.
WV...None.

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