textproduct: State College

WHAT HAS CHANGED

* Cold Weather Advisory issued for most of the area tonight into early Monday morning

KEY MESSAGES

1) One more bitter cold night before frigid conditions ease for the second week of February

2) A shortwave brings a slight chance of rain/snow showers to central Pennsylvania on Tuesday, with the chance for some post- frontal snow showers west of the Alleghenies Tuesday night into Wednesday.

DISCUSSION

KEY MESSAGE 1: One more bitter cold night before frigid conditions ease for the second week of February

One of the coldest late January-early February periods on record is [thankfully] about to come to an end. To cap it off, we will have to endure one more bitter cold night/early Monday morning.

This time around, cold wx headlines are triggered based on a mix of minimum air temperatures (west-central PA) and minimum wind chills (east-central PA). The floor for min temps around KBFD is in the -20 to -25F range based on traditional GFS/MAV MOS guidance. We employed a hedged approach (blending base NBM with 5-10%tile and MAVMOS) taking into account some factors (clouds or a light breeze) that may prevent "elite" radiational cooling from playing out. That being said, we still felt leaning colder was the best bet under clear skies/calm winds with snow on the ground and 1030mb high settling right over NW PA by 12Z Monday. Cold weather advisory is in effect from 10PM tonight to 9AM Monday.

KEY MESSAGE 2: A shortwave brings a slight chance of rain/snow showers to central Pennsylvania on Tuesday, with the chance for some post-frontal snow showers west of the Alleghenies Tuesday night into Wednesday.

Tuesday morning, warm air advection ahead of the shortwave may force a narrow, north-to-south band of light precipitation to set up, with 20-30% POPs in place across the Northern Tier for that period. A warm nose at 850 mb looks to coincide with this band, which may result in a brief period of light mixed precipitation. While precipitation will likely be light and quick to move out, air temperatures of around 20F suggest that some surfaces might become slippery.

Looking into the afternoon and evening hours, the cold front associated with this shortwave looks to quickly pass west-to- east across central Pennsylvania, bringing another chance for precipitation. During the time of this frontal passage, temperatures are expected to be above freezing outside of the Poconos, with precipitation looking to primarily be light rain.

Finally, residual low-level moisture combined with cold air advection may bring post-frontal snow showers west of the Alleghenies Tuesday night and into Wednesday.

AVIATION /06Z MONDAY THROUGH FRIDAY/

A very cold night is expected with widespread VFR conditions under mainly clear skies. Winds will be light through the TAF period as high pressure remains in control. Some patchy fog may form near BFD and JST in the 09Z-12Z timeframe, but visibility restrictions appear unlikely at those two airfields.

Mid and high clouds increase from the west during the afternoon ahead of an area of low pressure that will track to our north on Tuesday. Moisture will be very limited with this system, but a few snow showers are possible across northwest PA in the early morning as a warm front moves through.

Outlook...

Tue...Scattered snow showers.

Wed-Thu...Small chance for some very light mixed precipitation, mainly across the north. Trace amts.

Fri...Small chance for some very light snow across the south.

CTP WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 9 AM EST this morning for PAZ004>006-010>012-017>019-024-025-033-034-037-041-042-045-046- 049>053-057>059-065-066.