Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
978 FXUS61 KCTP 251023 AFDCTP Area Forecast Discussion National Weather Service State College PA 623 AM EDT Wed Sep 25 2024 .SYNOPSIS... * An upper trough and surface frontal system will bring overcast skies and showery conditions to Central PA through Thursday * Soon-to-be-Hurricane Helene will remain well southwest of Pennsylvania late this week, though a stationary front draped across the Mason-Dixon Line will keep showers in the forecast each day through the weekend. * Beneficial rainfall accumulation expected into next week for most as October kicks off. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Broad southeast flow continues this morning and will keep overcast skies in place all day. Showers and a few rumbles of thunder ongoing in NW PA associated with convergence/warm advection will drift northeast this morning. Drizzle/light showers will remain possible through much of the morning before more robust showers associated with a warm front lift northeastward. SPC has kept all of Central PA in a General Thunder area, though current thinking is that best instability will be confined to the Laurels this afternoon. Generally light rainfall accumulations expected today, with only spot amounts over a quarter inch of rain. Diurnal temperature ranges progged to be a modest +5 to +8 thanks to overcast skies and a moist airmass. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... The center of an upper trough will cross Quebec tonight into Thursday, helping focus a bit more lift across PA. At the surface, a weak front will drift through and provide enough lift to generate a more concentrated corridor of showers and perhaps a thunderstorm or two. Modest PWATs around 1.5" could produce some heavier rainfall, perhaps up to an inch with stronger showers/storms on Thursday afternoon. As the upper low moves to the northeast of PA Thursday evening, the associated upper level support will help sustain showers in northeast PA as a lull in the precipitation follows in western and Central PA in the wake of the cold front. The front will stall out across the Mason-Dixon Line Thursday night. As such, a few breaks in the clouds may occur Thursday afternoon in northwest PA. Farther south, the stretch of overcast conditions continues. A very mild night is in store Thursday night with lows ranging from +10 to +20 compared to average for this time of year, ranging from the middle 50s in the north to middle 60s farther south. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Rain remains in the forecast through the weekend. The highest chances will mainly be confined south of the Turnpike; however, can`t rule out showers making it as far north as the northern tier Friday evening into Saturday morning with Chc PoPs across the Laurels throughout the day on Friday and into Saturday morning. There is still some uncertainty in regards to how Helene will impact central Pennsylvania, mainly dependent on interactions with an upper-level low stationed across the eastern Tennessee Valley. Deterministic model guidance has outlined that the bulk of rainfall will stay west of the area while a rather narrow, negatively tilted upper-level ridge holds strong from the Great Lakes through the Upper Ohio River Valley. Given the uncertainty with regards to upper-low interactions, did not deviate much from continuity and NBM guidance this cycle. The upper-level low and remnants of the tropical system will likely drift east across the Commonwealth early next week, bringing increased chances of shower activity into the beginning of next week, with highest chances generally across the western highlands. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... TAFS in good shape overnight, with just some minor adjustments so far. Main item of interest is the thunderstorm to the southwest of BFD. Keeping an eye on it, but trend has been for the storm to weaken. The storm should stay a bit west of the BFD area. Main issue today will be MVFR to IFR conditions today into early Thursday, as a southeast flow of cool, moist air is advected to the north and west into the mountains. CIGS will likely not go up a lot today, as showers become more wide spread. However, the time of day should aid in CIGS getting a bit higher. Any improvement will not last, as CIGS will likely trend back down some as the sun sets. Outlook... Thu...AM low cigs/chc showers, mainly early. Fri...Patchy AM valley fog possible N Mtns. Chance of showers/low cigs across the south. Sat-Sun...Chance of low cigs/showers, mainly across the south. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Banghoff NEAR TERM...Banghoff SHORT TERM...Banghoff LONG TERM...NPB AVIATION...Martin