textproduct: Raleigh

SYNOPSIS

Arctic high pressure will weaken and modify over the Carolinas through Wednesday. A warm front will lift north across the region on Thursday. A cold front will sweep across the area late Thursday and Friday.

NEAR TERM /THROUGH TONIGHT/

As of 1225 PM Monday...

* Continued cold through tonight, with fair to clear skies.

A fast NW mid level flow will persist over the Mid Atlantic region through tonight, in the wake of the departing deep trough pushing NE over the Canadian Maritimes. A dry Arctic surface high will hold over the central and eastern Carolinas through tonight, with gradual modification. While it won't be quite as frigid as last night as low level thicknesses steadily rebound to 10-15 m below normal, given excellent conditions for radiational cooling and the deep nearly isothermal profile from the surface to ~700 mb, we should still see much below normal lows in the upper teens to lower 20s, with light winds. Thin cirrus clouds now over the Upper Midwest are on track to dive through the Mid Atlantic region overnight, and based on the wind profile, this moisture may be sufficient for a few hours of orographic enhancement in the northern Piedmont of NC late tonight. But overall, most high clouds should be fairly thin and unlikely to significantly impact radiational cooling. -GIH

SHORT TERM /TUESDAY AND TUESDAY NIGHT/

As of 1230 PM Monday...

Aloft, weak transient ridging will progress ewd across the region Tue/Tue night. At the surface, Arctic high pressure will gradually shift ewd and offshore on Tue, with a lee trough setting up east of the Appalachians Tue night. Cool, dry weather will prevail, with sunny/clear skies through the evening. Cloud cover may increase from the west Tue night/early Wed. After a chilly (upper teens to low 20s) start to the day, temperatures should rise into the mid/upper 40s on Tue. Lows Tue night mainly in the mid to upper 20s. With an increasing pressure gradient Tue night, especially across the north, wind chills my drop into the low 20s.

LONG TERM /WEDNESDAY THROUGH MONDAY/

As of 120 PM Monday...

* Widespread mixed character precipitation, stratiform rain and embedded showers, is expected Thursday night. Although no significant rainfall totals are expected.

* Strong winds and wind gusts possible ahead and especially behind cold frontal passage on Friday.

Forecast confidence remains medium-high in at least measurable precipitation is expected across central NC, with highest confidence towards the NC/VA border and lowest confidence towards the NC/SC border. This storm system will be driven by an anomalously deep area of low pressure, sub 990 mb, shifts across the Upper Great Lakes on Thurs and lifts towards Quebec and Newfoundland/Labrador provinces by Fri afternoon. Strengthening southwesterly flow ahead of the approaching cold front will pump highly anomalous deep layer moisture (0.75 to 1.25" PWAT values) into the area. Despite this favorable aligning of ingredient, the synoptic forcing for ascent is not particularly strong. Central NC will likely only be glanced by the best DPVA as the core of the compact shortwave is forecast to pivot across the Ohio Valley and northern Mid-Atlantic/Northeast. Main driver will likely be the interaction with the southern stream jet and resultant strengthening upper divergence over the Carolinas.

This pattern is not particularly favorable for any significant rainfall for our area, but a wetting rain of 0.5 to around 0.1 appears likely. Locally higher amounts of +0.75" will certainly be possible, but probability of > 1" in 24hrs remains around or below 5%.

Extreme drying aloft and strong subsidence will quickly shift across the southern Mid-Atlantic Fri which should quickly scour out cloud cover and result in mostly clear skies by the early afternoon. A lingering tight pressure gradient in the post-frontal regime combined with excellent insolation should provide a favorable pattern for strong downsloping winds of around 15 mph and frequent gusts 20 to 30 mph (infrequent gusts could reach as high as around 35 mph, based on momentum transfer in point soundings from the grand- ensemble).

AVIATION /06Z TUESDAY THROUGH SATURDAY/

As of 115 AM Tuesday...

Some orographically enhanced cirrus continues to move across the northern Piedmont and northern Coastal Plain. This will dissipate by early this morning. Otherwise, Arctic high pressure over the Southeast US will move east and offshore today, resulting in sunny skies and light SSW winds.

Outlook: VFR conditions will prevail through Wednesday. Flight restrictions and rain will accompany a frontal system across the region Thu-Thu night. Additionally, low-level wind shear will be possible Wed morning. VFR and dry weather will return on Friday and Saturday.

RAH WATCHES/WARNINGS/ADVISORIES

None.