textproduct: Raleigh

WHAT HAS CHANGED

As of 254 PM Monday...

SPS issued for slick roads via black ice tonight through Tuesday morning.

KEY MESSAGES

As of 254 PM Monday...

1) Bitterly cold temperatures tonight under lingering snow cover. Icy driving conditions will persist through Tuesday morning.

2) Moderating temperatures Tuesday through mid-week, followed by periods of cold Thursday into the weekend.

3) A cold front crossing the area will bring light precipitation from Tuesday night into Wednesday night. While mainly rain is expected, a brief changeover to snow at the end of the event can't be ruled out on Wednesday night, but any accumulations would be light and impacts should be limited.

DISCUSSION

As of 254 PM Monday...

KEY MESSAGE 1...Bitterly cold temperatures tonight under lingering snow cover. Icy driving conditions will persist through Tuesday morning.

Sfc analysis this afternoon showed the center of the high over the Deep South. This feature will continue to slide eastward through tomorrow. As the high nudges northward, low-level thicknesses should rise some overnight compared to this morning. Ranging from 1290-1295 tonight, these thicknesses would traditionally support lows around 20 or so. However, given generally clear to partly cloudy conditions expected tonight in addition to the lingering snow pack, expecting temps to drop more-so into the mid to upper teens. Given the calm winds, however, wind chills do not drop into cold weather advisory criteria tonight.

Given the cold temperatures expected along with additional melting from today's slight warmer temperatures and good sun, black ice will again be a concern tonight and during the early Tuesday morning commute.

KEY MESSAGE 2... Moderating temperatures Tuesday through mid-week, followed by periods of cold Thursday into the weekend.

Zonal flow aloft and sly return flow along the western ridge of the exiting sfc high will promote warmer daytime highs Tuesday in the mid to upper 40s. Increasing clouds and low-level thicknesses Tuesday night/early Wednesday will promote warmer overnight lows in the lower 30s.

Our next frontal system will approach and possibly push through some northern areas Wednesday afternoon. Ahead of the system, temperatures should still push into the 40s (northern areas might hover in the upper 30s). Behind the system, expect another cold blast with highs only in the mid to upper 30s Thursday and overnight lows Thursday into Friday in the upper teens. Another surge of colder air then looks possible Friday into the weekend.

KEY MESSAGE 3...A cold front crossing the area will bring light precipitation from Tuesday night into Wednesday night. While mainly rain is expected, a brief changeover to snow at the end of the event can't be ruled out on Wednesday night, but any accumulations would be light and impacts should be limited.

The upper pattern will amplify through the week, as a northern stream mid/upper trough digs across the lower MS Valley on Tuesday night and Wednesday, spawning a surface low and pushing a cold front through central NC. Ensemble guidance is in good agreement that precipitation will move in from NW to SE during this period along the front, so POPs have increased to high chance to likely. QPF amounts look light, around a quarter inch or less, and boundary layer temperatures should be warm enough for all liquid.

Additional precipitation is possible on Wednesday night as the shortwave amplifies and the surface low moves east across GA/SC. The best chance would be in the SE where the best forcing will be. A changeover to snow at the end can't be ruled out as the cold front will have moved through by this point and temperatures in the column cool to below freezing. Both deterministic and ensemble guidance of the GFS/ECMWF/CMC have gotten wetter, which has resulted in more ensemble members producing measurable snow. The best chance would be across the north. However, this is a case of cold air "chasing" the precipitation, which typically results in limited snowfall if any across our area. Still certainly worth monitoring.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

As of 650 PM Monday...

Arctic high pressure and dry air will favor VFR conditions over cntl NC through Tue, though with a band of 5-9 thousand ft ceilings that will move east and across cntl NC this early tonight. A veil of considerable high level cloudiness and associated 15-25 thousand ft ceilings will overspread cntl NC on Tue. Light swly stirring to calm tonight will strengthen with daytime heating Tue and may occasionally gust to near 15 kts during the afternoon.

Outlook: Flight restrictions and a chance of rain will result with the approach and passage of a frontal wave Tue night through Wed night; and that rain may change to a period of snow before ending Wed night.

Climate

Record Low Temperatures:

February 3: KFAY: 10/1917

RAH WATCHES/WARNINGS/ADVISORIES