textproduct: State College

WHAT HAS CHANGED

* Expanded mentions of dense fog overnight. Considering expansion of Dense Fog Advisory if conditions worsen. * PoPs generally increased in days 3-7 due to higher confidence in precip timing/occurrence.

KEY MESSAGES

1) Fog is dense in Schuylkill County. More locations could see fog by morning. Showers across the N.

2) Feeling more like early Spring than late Winter this week

3) Periods of rain Wednesday, Thursday night and Friday

4) Mixed/wintry precipitation potential for late week

DISCUSSION

KEY MESSAGE 1: Fog is dense in Schuylkill County. More locations could see fog by morning. Showers across the N.

Roadway sensors and KZER obs show that fog has become dense over the last 2-3hrs along and near I-81 in Schuylkill County. Sensors are now AOB 1/4SM with two of them just 500-600ft. Wind should remain light and from the southwest for much of the night. See little improvement happening there, and some expansion to the poor visibilities is possible.

The clear patch over SWrn PA has not begun to get foggy, but the dewpoints are progged to rise as the wind veers to the SW. This may help form fog where moisture remains high (like places where there is still snow on the ground). The showers across the nrn tier are likely riding atop the warm front as a weak wave rolls eastward along it. Precip should be showery and very brief, confined N of I-80, and mainly N of Route 6.

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KEY MESSAGE 2: Feeling more like early Spring than late Winter this week Following one of the coldest first 2 weeks of February on record, mild weather for this time of year will be in place this week with daily max/min temperature anomalies running 10-20 degrees above the historical average. Tuesday will feel like a real Spring day, but will probably start out kinda murky in places. First wave of precip (rain) is slated for Tuesday night, lasting into Wed. Wed's PoPs are categorical for the majority of the forecast area.

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KEY MESSAGE 3: Periods of rain Wednesday, Thursday night and Friday

Following one of the driest first 2 weeks of February on record, much needed periods of rainfall are likely on Wednesday and again Thursday night into Friday. Total QPF during the mid to late week period ranges between 0.50 to 1.00 inches with the highest amounts shaded toward the NW portion of the fcst area. While we do not expect the rainfall to cause flooding, the warmer temperatures and increased flows on rivers and streams should increase the risk of ice jams at least on the margin.

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KEY MESSAGE 4: Mixed/wintry precipitation potential for late week

Persistent boundary lingers into Friday with moisture pooling along it waiting for kickers to squeeze it out. Enough cold air may be trapped to the north of the front at the end of the week to produce mixed precip, or even snow for the northeastern zones.

Cold front looks like it will push through Friday or Friday night. Temps drop well behind it, bringing us back to normal - and then even colder later in the weekend or Monday. Development of a coastal/nor'easter is becoming more certain. The best deepening may not take place until it passes our CWA. Still, the upper low will be dropping in from the Great Lakes and should/could help generate a plowable snowfall later in the weekend. PoPs have increased to 40-60pct across the whole area on Sunday. LES for the few days after in cold NW flow. Sub- normal temps are possible early next week.

AVIATION /03Z TUESDAY THROUGH SATURDAY/

Some clouds never broke up this afternoon across the northern and easter tiers of the state. Clearing occurred in the southwest at JST and AOO, but VFR conditions at these two sites will not last long this evening. Most guidance shows low clouds and fog redeveloping overnight tonight. This should bring IFR or LIFR ceilings to most, if not all, of Central PA once again. The extent of visibility restrictions is highly uncertain, but BFD, JST, and AOO currently have the highest chance of seeing IFR visibility tonight. That being said, there is a 40-50 percent chance of all other TAF sites seeing visibility drop to IFR as well. Where clearing occurred fog will develop, and where low clouds remain they will likely lower to IFR or lower.

A low pressure system passing to our north tonight will bring a few rain showers to northern PA. While we expect most airfields to remain dry, there is around a 15 percent chance of a brief shower at BFD and IPT. Conditions Tuesday will be slow to improve with VFR not likely area wide. The best chance for VFR will be over the southeast at MDT and LNS after 18Z.

Outlook...

Wed...IFR -RA/cigs N, MVFR -RA/cigs elsewhere.

Thu...Dry early, then rain later in the day with restrictions possible.

Fri...Rain with restrictions likely. Some snow may mix in over northern PA.

Sat...Lingering rain and snow showers.

CTP WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 9 AM EST Tuesday for PAZ058.