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County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA
County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA
000 FXUS61 KPBZ 200836 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 436 AM EDT Tue Oct 20 2020 .SYNOPSIS... Periods of rain are expected through Tuesday along a stationary surface boundary. Well above normal temperature and drier conditions will develop by Thursday ahead of the next low pressure system this weekend. && .NEAR TERM /THROUGH TONIGHT/... Surface analysis show the cold front is beginning to enter the PBZ forecast area as the front is now through the New Philadelphia area, extending SW to NE. Latest radar trends indicate light rain gradually overspreading and increasing across the Ohio Valley in response to another low- amplitude shortwave trough propagating through broad cyclonic SW flow aloft and favorable right-entrance divergence of a 120kt jet streak. Additionally, the low-level jet looks to ramp up from about 30 kts to 45 kts overnight at about 850mb, continuing to bring more than sufficient moisture and warm advection at that level. HREF members generally agree precipitation will overspread much of the forecast area within the next few hours (with the exception of Morgantown and eastward). Precipitation coverage will peak in the morning and begin gradually diminishing thereafter as heights build in wake of the shortwave trough. Additional rainfall of up to a few tenths appears possible across most of the area north of the Mason-Dixon. Most NWP guidance progs the model stalling around noon in the vicinity of Allegheny County, extending to the north side of Wheeling to the West and northeast towards Brookville PA. Ample moisture and renewed warm air advection in the low- and mid- levels will lead to another dreary day for the Upper Ohio Valley and Allegheny Mtns region. 295-305k isentropic analysis shows quite a bit of lift again in the lower troposphere, with model soundings depicting a rather deep saturated layer above the near-surface cold pool (frontal inversion). This suggests a cloudy day with intermittent light rain showers or drizzle and perhaps even fog some areas of fog. A gradually improvement/clearing is likely from south to north through the day as the front retreats and the boundary- layer can mix out. However, the PA Laurel Highlands and Allegheny Mountains of WV/MD may get socked in again Tuesday night with an upsloping SE wind. Temps won`t budge much through the day, remaining in the 50s, especially north of the I-70 corridor. South of that (south of the front), better insolation and a better-mixed boundary layer may help raise values to the 60s or even 70. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... A deeper shortwave trough and its associated sfc trough will traverse the northern Great Lakes into southeast Canada Tuesday night into Wednesday. Due to the more northern track of this trough, forcing will be much weaker with the frontal boundary remaining hung up near the northwest portion of the CWA. At the same time, the southeast U.S. ridge will continue to build, causing pressure heights over the area to continue rising with warm advection at the sfc. The result will be isolated/scattered showers near the front Wednesday, with dry and well above-normal temperature for the rest of the forecast area. && .LONG TERM /THURSDAY THROUGH MONDAY/... A deepening central U.S. trough and building southeast U.S. ridge will further amplify warm advection for the upper Ohio River Valley Thursday into Friday, with sfc high pressure keeping the region dry. Almost summer-like temperature is expected Thursday with ample sunshine while Friday will be slightly cooler given increased cloud cover, though still well above seasonal average. The upper trough and associated sfc feature are expected to cross the region Saturday, though with the upper low core remaining well north of the region. Expect increased chances of precipitation and cooler temperature with its passage. The post-trough passage patterns remains unclear, but general consensus seems to keep the region in between the longwave trough axis over the central U.S. and the Atlantic Ridge. The resulting southwesterly flow will likely hold into early next week, buoying area temperature near seasonal averages while potential shortwaves within the flow bring periodic precipitation chances. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... Cig and vis restrictions are expected through most of the TAF period as a pseudo-stationary boundary remains across the area. Much of the area will start with VFR conditions, but these will deteriorate quickly as dawn approaches. IFR/LIFR cigs are expected through much of Tuesday with possibly the exception of MGW and LBE. A second round of showers will cross the region and continue through much of the afternoon. By this evening, the boundary should lift northwards as a warm front with a slow improvement to VFR expected to follow. .Outlook... Relative improvement is expected during the second half of the work week before another frontal system crosses this weekend. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$
| Forecast Discussion from: NOAA-NWS | Script developed by: El Dorado Weather |
