textproduct: Raleigh

SYNOPSIS

Cold high pressure will build in from the Midwest through Saturday, then track east off the New England coast Saturday night. A cold front will move south through the region Sunday, before settling just to our south Sunday night. A more significant storm system is expected to develop along this front over the northern Gulf on Monday, then track northeast along the Coastal Plain of the Carolinas Monday night through Tuesday night. Chilly high pressure will then build in from the west on Wednesday.

NEAR TERM /THROUGH TONIGHT/

As of 100 PM Friday...

* Coldest Night Of The Season

The center of Canadian high pressure(cP airmass), currently positioned over the mid MS Valley, will build directly overhead tonight. NWLY gusts of 15 to 25 kts this afternoon will diminish around sunset, with winds becoming light and calm overnight. The combination of calm winds, clear skies, and dry airmass with dewpoints in the teens, will promote excellent radiational cooling conditions.

The very cold low-level thicknesses of 1275-1280m, more typical of mid-winter, will result in the coldest night of the season. Expect lows in the lower to middle 20s, with some upper teens possible in outlying rural area(12-17 degrees below normal for late November).

SHORT TERM /SATURDAY AND SATURDAY NIGHT/

As of 100 PM Friday...

* Continued Cold/Chilly

Canadian high centered over the region on Saturday will drift east and will move off the mid-Atlantic coast late in the day, reaching the northern Atlantic waters by early Sunday. Downstream of a mid/upper level shortwave trough ejecting from the central Plains into the Ohio Valley and upper Great Lakes, quasi-zonal flow aloft will transition to backing SWLY flow Saturday night.

Despite compliments of full sunshine, temperatures will remain chilly Saturday, with highs in the lower 40s north to mid/upper 40s south --- 12-15 degrees below normal for late November.

Weak shortwave impulses coupled and strengthening warm moist air advection within the SWLY flow aloft will lead to increasing clouds Saturday evening, with skies becoming mostly cloudy Saturday night. The thickening cloud cover may produce a non-diurnal temperature trend overnight, with lows occurring during the first half of the night,followed by nearly steady or slowing warming temperatures toward daybreak. Lows in the mid 20s to lower 30s.

Overall model consensus favors keeping measurable precip chances after daybreak Sunday. However, a brief period of fleeting, patchy light freezing rain or drizzle cannot be ruled out across the NW Piedmont during the pre-dawn hours. Any impacts should be very limited in time and coverage, with temperatures rising above freezing shortly after sunrise.

KEY MESSAGES

- A chance of mostly light showers and milder Sunday as a cold front moves through the region.

- Cold and dry high pressure will follow the front on Sunday night and Monday.

- A strong mid/upper level trough will approach from the Plains states late Monday night and Tuesday, aiding in the development of a storm system along the Gulf Coast states Monday night.

- A cold rain is expected to develop/overspread much of NC Monday night night and Tuesday as the low pressure tracks NE along the Coastal Plain of the Carolinas. Rain lingers Tuesday night.

- At the current time, it appears that the coldest arctic air associated with the high pressure as it moves progressively from the Great Lakes to off the New England coast - as the rain develops and spreads into central NC - will remain just north of our region.

- P-Type is expected to be all rain at the current time, supported by the coldest air remaining just to our north (partial thicknesses that support snow/sleet remain north), warming in the mid levels to (50+ degrees at 5K feet) and a progressively moving high with the main precipitation event - essentially support cold rain and any freezing rain at the beginning of the event Monday night a fleeting non-hazardous issue.

- Remaining chilly with drier weather and some modification in temperatures with the sun returning Wednesday and Thursday.

LONG TERM DISCUSSION DETAILS...

Sunday will be milder with a chance of light showers with the passage of the cold front. Highs in the 40s west and 50s east. Some in-situ CAD in the Piedmont will keep it chilly there.

Conditions then turn chilly and if this were early January, we would have significant p-type issues. Still, this is a favorable pattern for p-type problems in the winter season and will have to be watched.

Trends continue to be wetter with widespread QPF of 1 inch currently indicated from late Monday night through Tuesday night as the low pressure tracks NE along the Coastal Plain of the Carolinas from the Gulf Coast states. For snow/ice, we would need the current arctic surface high pressure to drive more of the low level cold air deeper into the region Monday and Monday evening. It appears that the near surface and deeper cold remain just to our north. The high is also progressive - and the CAA ends as the precipitation begins. Another red flag.

Bottom line... Expect a cold rain late Monday night through Tuesday night. We will watch the forecast storm track and the arctic air mass over the coming runs to see if we need to trend toward some freezing rain mention over the Piedmont Damming region of north- central NC. Otherwise, it will be cold with the rain. Some areas hold in the 30s Tuesday.

After the system lifts out to the NE, expect a continuation of chilly conditions with some modification with the addition of sunshine by mid-week.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

As of 100 PM Friday...

Through 18z Saturday: A very dry, cold, and stable airmass(cP airmass) building into the region will support VFR conditions through the forecast period.

NWLY gusts of 15 to 25 kts will diminish this evening with winds becoming light and calm tonight as the surface high builds directly overhead.

Outlook: VFR conditions are likely to continue through early Sunday. A cold front will sweep east across the area Sunday afternoon into Sunday night, bringing a chance of showers and associated sub-VFR restrictions. The cold front will stall south of the area Monday with dry VFR conditions giving way to widespread rain/showers and sub-VFR restrictions late Monday night and Tuesday as a series of weak sfc lows/waves track through the SE US and up the Carolina Coast.

RAH WATCHES/WARNINGS/ADVISORIES

None.