textproduct: State College

WHAT HAS CHANGED

* Subtracted a deg or two from maxes M-W, but kept continuity for R-F to keep message the same for high heat and humidity.

KEY MESSAGES

1) Fog possible in sheltered valleys, mainly north, overnight as temperatures cool off into the 50s.

2) Low RHs

3) Warmth surges again later this week with dangerous heat possible Thursday and Friday.

DISCUSSION

KEY MESSAGE 1: Fog possible in sheltered valleys, mainly north, overnight as temperatures cool off into the 50s.

Diurnal cu should dissipate as the sun goes away. Selling tix to the battle between the dryness of the airmass vs cooling to the local dewpoints tonight to determine how much fog can form. Current odds (62.7%) are that fog will form in the deepest river valleys - mainly of the north - tonight. But, the coverage will be rather limited. While the airmass is dry, the temps should be dipping to and perhaps below the crossover temps (mid- aftn dewpoints) in the lower elevations of the Allegheny Plateau. Otherwise mainly clear sky and light NE wind, if any, will make for a window-open night.

--------------------------------------------------------

KEY MESSAGE 2: Low RHs

RH will dip into the upper 20s and 30s Mon, and 30s over the east on Tues. Paired with relatively light wind and the greened- up landscape, though, it should yield no elevated risk for rapid wildfire spread.

--------------------------------------------------------

KEY MESSAGE 3: Warmth surges again later this week with dangerous heat possible Thursday and Friday.

While the NBM max temps have inched lower by 1-4F for the next couple of days, the latter half of the week still looks hot. 90s should be widespread Thurs and Fri. The elevations of the Alleghenies will be the coolest spots, but the valleys there could also get to 90F. Heat Index/ApparentT values remain virtually unchanged for those two days.

The new/cooler temps T-W are likely due to the raised cloud cover and higher chc of precip vs prev guidance. Categorical (80%+) PoPs appear Tues night over the west as moisture increases and sct TSRA are expected. These shouldn't get too far to the east, perhaps staying W of UNV/AOO. Wed will hold widespread SHRA/TSRA over the bulk of the CWA as the upper ridge weakens and shortwaves (old MCSs) crest the ridge and meet up with the increasing moisture.

Only slight relief arrives Sat, but temps remain very warm/hot. The 6-10 and 8-14 day outlooks are for continued above normal temps (and precip). Above normal precip would help out the areas that continue to be in drought.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Lingering low-level moisture (Td in the 50s-60s) behind this morning's frontal passage will maintain a diurnally driven cumulus field through this evening. Otherwise, a high pressure will slide down the Adirondacks tonight, bringing a chance for patchy fog across the Northern Tier (KBFD) and East-Central Mountains (KIPT/KUNV/KAOO) where clear skies and light winds will be most favorable for radiative fog. Using a GLAMP/HREF blend, flight restrictions are possible (30-50% chance) at KBFD, with lower probabilities (20-30% chance) elsewhere at this time, although KUNV is slightly favored for patchy mist/fog on current model guidance vs. KIPT/KAOO.

This high pressure will also bring a backdoor cold front to our easternmost terminals (KIPT/KMDT/KLNS) Monday morning (09Z-12Z). The GLAMP highlights a low chance (20% chance) of MVFR with the clouds behind this front, though uncertainty regarding sky cover precludes ceiling restrictions in TAF at this time. Diurnal VFR cumulus field redevelops across much of central Pennsylvania during the daytime Monday as the front diffuses & return southerly flow develops on the western periphery of the high pressure.

Outlook...

Mon-Tue...VFR favored outside of isolated morning fog. Restrictions possible in -SHRA/-TSRA early Sun & again late Tue.

Wed-Fri...Restrictions possible in -SHRA/-TSRA.

CTP WATCHES/WARNINGS/ADVISORIES

None.