textproduct: Columbia

WHAT HAS CHANGED

A Cold Weather Advisory has been issued beginning this evening and continuing into Monday morning. Black ice will be possible Monday morning it spots as any lingering liquid or snow on roadways will refreeze.

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 is settling over the southeastern US is leading to very cold temperatures. This is being compounded by the snow pack that is beginning to melt, but will take awhile across northern portions of the area that received significant amounts of snow. Clear skies into tonight along with winds becoming light with high pressure ridging into the area will lead to strong radiation cooling, again enhanced by the snow. 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. Cold Weather Advisory will be in effect from 6pm tonight to 10am tomorrow. While there is some melting going on today with sunny skies, 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 /18Z SUNDAY THROUGH FRIDAY/

VFR Conditions Expected Through the TAF Period.

Gusty winds still expected through late this afternoon. High pressure will build into the region tonight and into Monday. Skies will be clear, and for the most part visibilities will be unrestricted through the period. With lingering snow pack across the area, and light to nearly calm winds tonight, can not completely rule out some patchy freezing ground fog development, but confidence is very low at this time. With temperatures rapidly dropping back below freezing after sunset, any lingering moisture on airport runways could refreeze and cause hazardous conditions through Monday morning. EXTENDED AVIATION OUTLOOK...VFR conditions are expected through at least the first half of the work week. Another system moving through the region mid-week could bring restrictions once again. At this time it appears precipitation will fall as rain.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Cold Weather Advisory from 6 PM this evening to 9 AM EST Monday for SCZ016-018-020>022-025>031-035-037-038-041-115- 116-135>137. GA...Cold Weather Advisory from 6 PM this evening to 9 AM EST Monday for GAZ040-063>065-077.