Marine Weather and Tide Forecast for Harrisburg, PA

NEAR TERM /THROUGH TONIGHT/
Shower activity has waned considerably this morning as shortwave energy continues to drift east of the area. Rainfall totals yesterday and overnight were highest across south central PA - as expected - with widespread 2-4" amounts and local totals exceed 5". River Flood Warnings remain in effect for the Youghiogheny at Confluence and Aughwick Creek at Shirleysburg and several other streams/creeks saw significant rises overnight.

With an upper low continuing to swirl nearby today, diurnally driven showers and perhaps a thunderstorm or two are expected once again this afternoon. HRRR PMM QPF depicts only widely scattered accumulation with amounts greater than 1" unlikely at this time. Mostly cloudy skies and a cool/moist easterly flow will limit instability and help keep temperatures in the 60s for all but south central PA, where the low 70s are likely.
Drizzle/ridge shrouding fog is expected through the day with little improvement expected.

Overnight, shower activity should taper off even further, but lowering ceilings/inversion height will support continued drizzle/low clouds and perhaps some fog. Low temperatures by daybreak Thursday will be in the upper 50s and low 60s.

SHORT TERM /THURSDAY THROUGH FRIDAY/
The upper trough that has brought unsettled weather for the better part of the week will weaken and lift northeast Thursday and Friday. However, an upstream trough in the northern stream will be approaching from the Great Lakes region. This energy, plus a warm frontal approach Thursday, then a cold frontal one Friday, will bring more diurnally favored showers and storms.

Latest hi-resolution model guidance is beginning to come into range for thunderstorm evolution Thursday night into Friday morning ahead of the approaching warm front. Ample shear and sufficient lift from the front could support a line of strong thunderstorms racing across the Great Lakes later Thursday into Friday morning. Storms could bring some gusty winds on Friday morning as the parent lo occludes and deepens in the upper Midwest. SPC has placed the western two-thirds of PA in a Marginal Risk of severe weather for early Friday morning.

Afternoon highs Thursday and Friday will trend warmer each day (70s-lower 80s), given the anticipation of breaks of sunshine and winds shifting to come out of the southeast (Thursday) and then southwest (Friday).

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
The next system to watch will be an incoming short-wave in the northern stream tracking from the Upper Midwest across the Northeastern CONUS this weekend. The combination of that short- wave and a surface frontal complex will bring lingering convection on Saturday.

Still some uncertainty on Sunday with a cyclonic flow aloft and the passage of a secondary surface cool front. Thus, there remains enough uncertainty to justify the mention of at least scattered showers for the second part of the weekend. Upper ridging will build in toward the start of next week, but uncertainty remains with how quickly the brighter/drier conditions build in. On the optimistic side, Sunday evening could see plenty of sunshine. Pessimistically, sunshine may wait until Monday.

Early next week, model trends favor at least a brief period of drier conditions, with short-wave ridging aloft and a surface anticyclone building down from south-central Canada. The break in the clouds/rain will be relatively short-lived with another storm system approaching by the middle of the week.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/
Extensive cloud cover and cool temperatures will keep the chance of showers less today. Main area of convection just east of our area. Few showers just south of far western PA. Thus used VCSH in the 18Z TAF package.

Expect low CIGS into Thursday morning, with some fog overnight.

As the sfc and upper level low edge just to the east of our area Thursday morning, expect conditions to improve some by early afternoon on Thursday.

Outlook...

Fri...Morning storms (some could be strong), improving conditions in the afternoon.

Sat...Mainly VFR, isolated PM showers/storms.

Sun...Some improvement, as a series of cold fronts move southeast of the area.

Mon...Mainly dry with VFR conditions. Perhaps a shower early at BFD and JST, with MVFR CIGS early at these sites.

CTP WATCHES/WARNINGS/ADVISORIES
Flood Watch until 10 PM EDT this evening for PAZ033-034.