textproduct: Raleigh

SYNOPSIS

A strong Arctic cold front will move southeast through the area today. Frigid high pressure will build over the region Monday, then move to our south Monday night and Tuesday.

NEAR TERM /TODAY THROUGH TONIGHT/

As of 320 AM Sunday...

* A Cold Weather Advisory has been issued for all of central NC from Sun evening to mid morning Mon, for wind chills as low as 3F-10F. * Sustained winds of 15-25 mph and gusts up to 25-35 mph expected this morning through this evening. * Light rain possible through 13Z today along and ahead of the front.

As of 07Z, the cold front was crossing the Appalachians. Scattered pockets of light rain were seen on radar along and just ahead of the front. The front and light rain are expected to sweep across central NC between 10Z and 13Z today, followed by a rapid change in sfc wind to NW along with increase in speeds to 10-20kt with gusts up to 30kt. Skies will clear from NW to SE as winds turn to a downsloping NW direction along with drier and colder air rushing into central NC from the N and NW. High temps today will occur between now and 10Z, then temps will actually fall through the 30s during the sunny daytime hours, and continue to plummet tonight with readings dropping into the teens. The wind will make it feel even worse with wind chill values plungING through the day, reaching the single digits in many areas by early evening, supporting the cold weather advisory starting at 6 PM and running through Mon mid morning.

SHORT TERM /SUNDAY AND SUNDAY NIGHT/

As of 220 PM Saturday...

LONG TERM /MONDAY THROUGH SATURDAY/

As of 1210 PM Saturday...

* Continued cold Tues morning, but warming trend expected Tues through Thurs night.

* Forecast confidence remains low for Thurs into Fri morning with our next precipitation chances.

A highly anomalous ~1040mb area of surface high pressure will be positioned over the southern/central Appalachians Mon morning will broaden as it spills across the Southeast and southern Mid-Atlantic into Tues morning. A weak pressure gradient and relatively favorable surface high location Mon night into Tues morning should support favorable conditions for excellent radiational cooling, especially with Mon afternoon dew points still in the single digits. However, a pocket of mid-upper level moisture shifting through the Ohio Valley Mon night will likely become orographically enhanced as it progresses east of the Appalachians and over the Mid-Atlantic after midnight. The thickness and areal extent will likely drive the temperatures into Tues morning. Latest forecast of mostly low 20s to upper teens remains in line with general consensus among the latest statistical guidance, but if the cloud cover is thinner than anticipated, then mostly mid/upper teens would be possible with urban areas around 20 degrees.

A compact shortwave shifting across the Great Lakes and Northeast Thurs into Fri will be embedded within predominantly zonal flow aloft and will drive our next precipitation chances. Amplitude and speed of this wave remains highly uncertain with this wave with an added complication of southern stream influence and/or phasing with the northern stream wave. Forcing for ascent is quite weak as the best H5 height falls, from an ensemble mean approach, will likely occur north of central NC over the northern Mid-Atlantic and Northeast with weakening 700 and 850mb WAA spreading into the Mid- Atlantic. This pattern will likely not support any significant/hazardous precipitation with forecast rainfall amounts of less than or equal to 0.10".

It is worth noting an alternative scenario which is primarily being driven by the ECMWF and its ensemble members. This forecast system suggests a more amplified shortwave and perhaps a brief phasing with the southern stream jet over the eastern CONUS. This would result in stronger horizontal WAA and development of weak MUCAPE ahead of the approaching cold front and support the potential for higher rainfall totals. This solution is considered an outlier among 00z guidance, but worth monitoring for the threat of stronger wind gusts and moderate to heavy rainfall in addition to lightning.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

As of 320 AM Sunday...

Through 06Z Monday... MVFR cigs and patchy light rain will spread west to east across central NC over the next few hours ahead of the cold front. Then the front will cross central NC between 10-13Z today, quickly followed by improving cigs but a rapid increase in winds in the wake of the front. Winds will become NW behind the front with speeds of 13-25kts and gusts up to 30kts which will last during the entire daylight hours. We'll see the gust diminish after sunset, but speeds will remain 10-15kt overnight.

Outlook: VFR conditions appear likely through Thursday.

RAH WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory from 6 PM Sunday to 9 AM EST Monday for NCZ007>011-021>028-038>043-073>078-083>086-088-089.