Sunrise 5:48 AM   Sunset 8:27 PM Moonrise 3:48 PM   Moonset 2:48 AM

  Print   HELP   Reset   Save   Recall  New

FXUS61 KCTP 190324 AFDCTP

Area Forecast Discussion National Weather Service State College PA 1124 PM EDT Sat May 18 2024

SYNOPSIS
An upper trough overhead will slide east through the late evening with showers decreasing by late tonight. High pressure will start to build into the region on Sunday accompanied by generally rain-free conditions that are expected to hold through the middle of next week. A storm system should arrive late Wednesday into Thursday bringing the next chance of showers and thunderstorms to the area.

NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
Isolated open cellular showers continue to roam areas from the N Central Mountains to the WC Mountains late this evening as upper low upper low tracks off the coast and drier air works southward behind the upper trough axis. Showers will taper by late tonight with clearing skies and light winds allowing areas of fog to form overnight. Some fog could become locally dense in the predawn hours. Lows will range from the mid 50s to around 60.

SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/
High pressure rolls in for Sunday. Clouds/fog in the AM clear out nicely. However, just enough instability develops and enough moisture lingers to pop a couple of SHRA. Literally just a few with the highest probability (30pct) over the SErn hill tops.
Maxes in the 70s will be pretty normal. We are likely to see some areas of fog again Sunday night with the sky clearing out better, but dewpoints not dipping out of the m50s.

A decent and mostly rain-free stretch of weather is expected Monday through Wednesday morning, with high pressure dominating the sensible weather conditions and bringing the driest weather we've seen in a few weeks. We are timing the next weather system into central PA by Wednesday afternoon. Scattered showers and thunderstorms may approach western areas by late Wednesday afternoon, but it looks like most areas stay dry until after 00z Thurs.

LONG TERM /WEDNESDAY THROUGH SATURDAY/
Late evening update holds minor changes to the long-term forecast, most notably have capped PoPs at Chc Wednesday evening into Thursday as both GFS/ECMWF models have showers/thunderstorms along the cold front breaking up as they enter central PA. Ensemble plumes still outline higher chances of PoPs in this timeframe so have decided to just cap instead of trim PoPs at this time.

Prev...
By the middle of next week, upper troughing will move across Pennsylvania and support a better chance for showers and thunderstorms. At the surface, there remains plenty of model uncertainty about the timing of a cold front. The mean timing is Wednesday afternoon, but individual models bring rain as late as Thursday morning. If the front moves through Wednesday afternoon or evening, it could produce the first threat for severe weather in some time given the aforementioned WAA bringing greater instability.

After the front moves through, considerable uncertainty exists in terms of how much and how frequent rain will be. A chance of showers remains in place through the end of the week despite zonal flow aloft providing little in the way of synoptic forcing. The next chance for a widespread soaking rain will come during the weekend with a center of low pressure developing across the Ohio Valley by Friday afternoon.

AVIATION /03Z SUNDAY THROUGH THURSDAY/
03Z Update: Minimal changes outside of slightly later (1-2hr)
later on fog development overnight with generally the same time for mixing out. A period of MVFR cigs possible tomorrow compared to earlier guidance but VFR expected by the afternoon hours.

Prev...
The main concern overnight will be fog formation at all airfields across central PA. The bulk of recent guidance outlines IFR conds in the 04-07Z timeframe, with most likely timing between 05-06Z where the potential for calm/light winds becomes slightly higher. This is echoed in recent RAP model soundings, thus have these restrictions in with moderate (50-60%) confidence. There is some uncertainty in regards to which airfields go down to 1/4SM vsbys and VV cigs after during the early morning hours Sunday morning. Highest confidence (40-50%) remains at AOO/UNV/IPT, with some potential for these conds at JST/BFD. Further to the SE, cannot rule out some lower- level clouds (below 300ft AGL) to bring LIFR conds to LNS with moderate (40-50%) confidence while retaining IFR conds at MDT based on a combination of RAP/GLAMP guidance.

After sunrise, some lingering low cigs/vsbys remain possible through 14Z Sunday before rapid improvement (in a 1-2 hour period) towards VFR is expected by the late morning. Once conds prevail to VFR, expect these conditions to continue through 00Z Monday.

Outlook...

Mon...Patchy AM fog possible. Otherwise, becoming VFR.

Tue...Predominantly VFR, w/ no sig wx expected.

Wed...Sct to widespread SHRA/TSRA return.

Thu...Chc of TSRA.

CTP WATCHES/WARNINGS/ADVISORIES
None.

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

State College, PA,