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
479 FXUS61 KCTP 141352 AFDCTP Area Forecast Discussion National Weather Service State College PA 952 AM EDT Tue May 14 2024 .SYNOPSIS... An area of low pressure over Missouri early today will drift slowly east and weaken, while a second low forms to the south of Pennsylvania later tonight and Wednesday. These two weather features, along with a slow moving front drifting southeast from the Lower Great Lakes, will bring periods of showers today through Wednesday. Drier conditions will follow for expected Thursday into early Friday before the chance of rain increases headed into the upcoming weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Clouds advancing and thickening from south to north this morning with patchy light showers and drizzle along the northern periphery of advancing deep layer moisture transitioning to scattered light to moderate showers of increasing frequency across the southern tier. The afternoon will be cloudy with isold to sct showers most numerous across the south. Best chance for an elevated tsra will be near the MD border, and even then it`s marginal given MU CAPE of only a few to several hundred J/KG at most. Max temps today will be in the U60s across the higher terrain of the North and West and in the low 70s throughout the valleys of Central and Southern PA. Southerly winds will be highest near and to the east of the Susq Valley beneath a moderately strong southerly LLJ. Sfc wind gusts in that part of our CWA will be in the upper teens to low 20s (KTS) with gusts further west only in the low to mid teens. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... The Mid Miss/Lower Ohio River Valley sfc low will weaken with a secondary surface low developing over N Carolina/Southern VA later tonight/early Wednesday ahead of an approaching shortwave. This storm track will result in gradually backing llvl flow keeping mainly overcast skies, relatively cool and stable air with occasional showers across the CWA through Wednesday. Slightly higher, but still unimpressive instability will occur in a relatively narrow channel along and ahead of a quasi-stnry/slow moving cold front across NW PA tonight and Wednesday. Ensemble plumes suggest generally around a half inch of rain or less for most spots by Wednesday evening. There could be a few locations that see around 0.75 inch of rain over the 36 hour period ending at 00Z Thu. Lows tonight between 55 and 60 will be notably milder than early Tuesday`s mins. Temps Wednesday will only climb (at best) by 8-10 Deg F as the 850 mb low center via the GEFS drifts over the Delmarva region and the nose of an approx -2 sigma Southeasterly 925-850 mb jet drifts N over the Mid Atlantic Piedmont region. Current forecast maxes Wednesday may even need to be trimmed by a few to several deg F. Strongly doubt we`ll see much in the way of breaks that could lead to warmer highs than expected. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Rain/frequent showers will taper to scattered showers with areas of drizzle and fog for Wed night as the low exits the Mid Atlantic coast. Thursday still has the possibility of being dry for most locations. Some guidance is depicting somewhat of a ring of fire feature across western and northern areas with isold diurnal shra or tsra possible, but for most areas the shortwave ridging should keep it dry. Left the 20-30 PoPs in for Thurs given by the National Blend respecting the low predictability of timing and strength of mesoscale features, like the aforementioned small ridge aloft, at this range. On the large-scale, a fairly zonal upper-level flow pattern is expected across the CONUS from late this week into the early portion of next week. Within this zonal flow, an energetic northern stream will keep frequent short-waves and surface frontal passages traversing the northern tier of states, including PA. Although the above described pattern is not likely to feature any complete washouts or widespread heavy rainfall, not many completely dry days are foreseen either, with at least hit and miss showers likely to prevail. The most widespread shower activity could occur on Saturday, with a surface wave anticipated to track south of the Commonwealth, and a relatively cool E-SE flow pattern in place in the lower levels. Outside of that, as alluded to above, showers should be mostly scattered in nature and diurnally centered on the afternoon and evening hours. Temperatures should average close to seasonal normals for mid- May, with mostly upper 60s-70s foreseen by day. The one exception is Saturday, when upper 50s and 60s are most probable. Given lots of clouds and shower activity, any frost/freeze conditions appear highly unlikely, with night-time lows mostly in the 50s. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... The day will begin with VFR conditions across the board; however, expect thicker clouds to begin advecting into the region with gradual lowering throughout the late morning into early afternoon. MVFR ceilings will move in from southwest to northeast during the afternoon as occasional showers and a few thunderstorms drift across the region. Ceiling heights will generally continue to lower through the afternoon and into the evening with most sites likely to see IFR cigs after 0Z Wednesday. A few rumbles of thunder could be possible with some of these showers this afternoon and tonight, but instability is the limiting factor and confidence in the coverage of thunder is relatively low. Patchy fog development is also expected overnight tonight and into Wednesday morning making IFR conditions likely to stick around to start tomorrow. Outlook... Wed...Restrictions in showers/t-storms and low ceilings. Thu...Slow improvement, with a few lingering showers possible. Fri...Deteriorating conditions with showers increasing. Sat...Showers continuing with reductions. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/DeVoir NEAR TERM...Lambert/DeVoir SHORT TERM...Lambert LONG TERM...Guseman/Jurewicz/Dangelo AVIATION...Banghoff/Bowen