textproduct: State College

WHAT HAS CHANGED

*Continue to slow the rise of temperatures today as persistent cold wedge keeps cloudy/damp/cool conditions along and east of I-99/US-15.

KEY MESSAGES

1) Cold air damming keeps eastern PA in the gloom while western PA experiences a temperature boom through Friday morning. 2) Temperatures soar to near record levels Friday and Saturday ahead of a strong cold front on Saturday night. 3) Trending colder and drier for Easter Monday and beyond.

DISCUSSION

KEY MESSAGE 1: Cold air damming keeps eastern PA in the gloom while western PA experiences a temperature boom through Friday morning.

Huge differences in conditions across the Commonwealth this afternoon with sunshine and highs in the 70s to near 80F across the west and clouds/drizzle with temps in the 40s and 50s in the east. This temperature distribution is brought to you by a classic springtime CAD pattern. Hires model data shows scattered showers developing late this afternoon and evening with max thunder probs along and west of the Allegheny Front/US-219 where instability will maximized.

The cold wedge will remain in place overnight and into Friday morning with ridge-shrouding clouds/fog and periods of rain expected to continue. Lows tonight will still be quite variable from west to east with lows in the mid 50s west of I-99/US-215 and and upper 30s to low 40s along/east of US-15.

KEY MESSAGE 2: Temperatures soar to near record levels Friday and Saturday ahead of a strong cold front on Saturday night.

A major surge of warmth for early April returns to CPA into Easter weekend with max temps fcst to approach and potentially break daily records Friday and Saturday, April 3-4 (see climate section). Intensity of scattered convection will coincide with peak heating and a few loosely organized storms cannot be ruled out, particularly on Saturday PM. Rainfall totals through Saturday night are >1" across the NW zones where 1-2+ inches have already fallen in the past 72hr. WPC highlights a Marginal Risk of excessive rainfall in northwest PA on Saturday. SPC outlines a Marginal (level 1 out of 5) risk for southwest PA clipping western Somerset County on Friday and then a more widespread Marginal Risk on Saturday across most of the area.

A strong cold front will push through the region Saturday night into Sunday morning, likely impacting Easter morning sunrise services. Morning temperatures in the 50s across the northwest will fall through the day in the wake of the front. Frontal passage coincident with a relative minimum in daytime heating should limit much threat of severe weather along the front itself, but a round of torrential rain and some gusty winds along the front is likely.

KEY MESSAGE 3: Trending colder and drier for Easter Monday and beyond.

Temp trends may go neutral to non-diurnal during the afternoon on Easter Sunday preceding a chilly start to next week. Highs are below the historical average Mon-Wed likely reaching a nadir on Tuesday/Tuesday night. Widespread sub freezing temps are fcst Tuesday night or a few days before the climatological growing season gets underway in the Lower Susquehanna Valley.

From a precipitation perspective, scattered rain and/or snow showers are possible Monday and Tuesday, especially in northwest PA with a classic northwest flow pattern. High pressure builds by Wednesday with a brighter/less cloudy second half of the week. The outlook trends drier into the middle of April, though nearby fronts could still bring brief rounds of (mainly light) precipitation.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Widespread LIFR conditions are currently being observed across all of the western terminals, with high confidence (~80-90%) in these conditions continuing on the whole through 10Z Friday with ample low-level moisture in place across the region. The one airfield that could see some improvement in the near-term would be JST where recent HREF guidance does indicate less low-level moisture in place compared to BFD/AOO/UNV. Any window for improvement at JST would come between 09-12Z where a quick transition from (L)IFR to VFR conditions seem the most likely solution at this time. Another concern across the western airfields will be the increasing potential for LLWS (especially across BFD/JST) between 04Z-15Z Friday. LLWS concerns outlined fairly well in NBM/NAM model guidance as these airfields are just south of a 50-60kt LLJ outlined in recent HREF model guidance. The 00Z TAF cycle has introduced these mentions with high (~60-70%) confidence at BFD and moderate (40-50%) confidence at JST within targeted timeframes for each terminal.

Further east, a mixed bag of observations are currently present; however, high confidence in further deterioration between 00Z and 06Z Friday with increasing confidence in LIFR conditions. Once LIFR conditions settle into each airfield (high confidence at MDT/LNS, moderate at IPT), conditions will remain through at least 15-17Z Friday with low clouds being the main driver for these restrictions. Gradual improvement is expected based on HREF/NBM model guidance within the 17-20Z Friday timeframe with moderate-to-high (50-70%) confidence in VFR conditions prevailing after 20Z Friday.

Outlook...

Sat...VFR conditions and dry for much of the time, but some showers and storms at times, as a frontal system will be nearby.

Sun...Restrictions possible with showers and thunderstorms ahead of a strong cold front.

Mon...Breezy and cooler with MVFR N/W, VFR elsewhere.

Tue...Sct snow/rain mix.

CLIMATE

Daily record max temperatures for April 3rd and 4th:

SITE APRIL 3 APRIL 4 Harrisburg 86/1963 | 82/1999 Williamsport 83/1963 | 84/1921 Altoona 81/1963 | 80/1950 Bradford 80/2010 | 72/1981 State College 79/1963 | 81/1910

CTP WATCHES/WARNINGS/ADVISORIES

None.