textproduct: Columbia

WHAT HAS CHANGED

Cold Weather Advisory now in effect through 9 AM Monday morning. Black ice will be possible Monday morning in spots as any lingering liquid or snow on roadways will refreeze. Aviation discussion updated.

KEY MESSAGES

- 1) Well below normal temperatures through early this week. Black ice may lead to hazardous travel in spots Monday morning.

- 2) Rain chances ramp up mid week ahead of a cold front.

DISCUSSION

KEY MESSAGE #1: Well below normal temperatures through early this week. Black ice may lead to hazardous travel in spots Monday morning.

An arctic air mass continues settling over the southeastern US this evening. Clear skies into tonight along with winds becoming light and high pressure ridging into the area will lead to strong radiation cooling. Cooling is expected to be enhanced by any residual snow pack which did not melt earlier today. Went a bit below blended guidance for lows tonight as it guidance typically struggles in these scenarios. This leads to Cold Weather Advisory criteria for the area, even with winds becoming mostly light as air temperatures expected to drop into the low teens and even single digits in the northeastern area. As such, the Cold Weather Advisory is now in effect through 9 am Monday morning. It should be noted that any lingering snow or liquid on untreated roadways will refreeze tonight in spots which may create hazardous travel conditions. Another potential hazard tonight into Monday morning will be the development of freezing fog which some of our higher resolution models are indicating, but widespread freezing fog remains unlikely.

A gradual warmup is expected into mid-week, with temperatures likely near average by Wednesday which will continue to aid in melting and by mid week, it'll be unlikely that any snow will be left.

KEY MESSAGE #2: Rain chances ramp up mid week ahead of a cold front.

An upper level trough will dig into the Southeast mid-week. Deep SW flow will promote warm, moist advection with temperatures rising into the low to mid 50s for Wednesday. As the associated surface low and frontal system approach the forecast area we will see PWAT values rise to around 1 inch. Convergence ahead of the cold front and synoptic scale lift from the upper trough favor likely PoPs from Wednesday morning to the evening. Although colder air will move into the area behind the front, any moisture will have likely exited the area already.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR conditions expected to continue through the TAF period.

Winds have continued to relax with most areas seeing westerly winds between 3-5 kts. Lights winds likely continue tonight with some locations going calm as high pressure builds in. There is some cirrus off to the west in northern GA that may move in overnight, but besides that mostly clear skies are expected with plummeting temperatures. This will allow any moisture from snow melt to refreeze overnight before temperatures rise above freezing between 15-17z. While patchy freezing fog continues to look unlikely tonight (less than 20% chance) it cannot be fully ruled out a couple hours near sunrise. After this winds remain light out of the west through the day and to the end of the period with mostly clear skies.

EXTENDED AVIATION OUTLOOK...VFR conditions are expected through at least the first half of the week. Another system and front moving into the area during mid-week could bring restrictions back to the region.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Cold Weather Advisory until 9 AM EST Monday for SCZ016-018- 020>022-025>031-035-037-038-041-115-116-135>137. GA...Cold Weather Advisory until 9 AM EST Monday for GAZ040-063>065- 077.