textproduct: Raleigh

SYNOPSIS

High pressure will be offshore of the SE states today and tonight. A weak wedge or CAD front will develop over the Triad this afternoon and linger tonight. A strong cold front will sweep across the region Wednesday. Cold high pressure will follow the front for Thanksgiving through Saturday.

KEY MESSAGES

- Light rain is expected to develop/overspread the NW Piedmont late late this morning into the afternoon. This expected rain and extensive cloud cover will likely lead to in-situ CAD over the NW Piedmont/Triad later this afternoon into tonight.

- A fairly large gradient of sky cover and temperature will result. Conditions will range from cloudy/cool and rainy NW to partly sunny, breezy, warm in the south and east.

- Some of the rain/showers will move east into most of central NC tonight. However, rainfall will be light (averaging 0.10 to 0.40). The higher totals will be in the NW, lower SE.

As light rain develops near an approaching warm front in the west, a CAD surface boundary will develop over the NW Piedmont. It may very well split the Triad according to the latest model consensus. To the east and south, it will be considerably warmer with a S-SW breeze with highs in the 70s.

Some rain and showers will continue tonight, but rainfall amounts will be light. The in-situ CAD low stratus/fog/mist will persist in the NW, but may shift into the NW Foothills in time tonight as the cold front approaches. Temps remaining steady NW (50s) with 60s in the SE.

SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/

As of 320 AM Tuesday...

-KEY MESSAGES...

- A strong cold front will drive through the region around mid-day into the afternoon Wednesday.

- We are in general thunder (from SPC) and it appears only weak and generally isolated low topped thunderstorms are possible.

- Warm weather until CAA arrives mainly Wednesday night behind cold front (70s).

- Turning colder and breezy Wednesday night (30s).

Lingering CAD in the Piedmont will give way to mostly cloudy skies with scattered showers. To the east, scattered showers and an isolated storm can be expected as the cold front moves through. The timing of the front should be around mid-day, earlier in the west and later in the east. The showers will end as the front moves through. The true CAA will arrive late or Wednesday night as another mostly dry secondary front surges through.

Breezy SW winds 10-20 mph will occur, shifting to the NW late in the day and at night. Highs will generally be in the 70s. Lows will dip into the 30s to near 40 SE.

LONG TERM /THURSDAY THROUGH MONDAY/

As of 125 AM Tuesday...

* Marginal Fire Wx concerns Thurs and especially Fri.

* Low forecast confidence as we head into a potentially more active pattern Sun into early next week.

Forecast confidence remains high in a dry forecast for Thurs through Sat as well-below normal PW values (less than 0.2") will be directed across much of the Mid-Atlantic and Southeast. There will however be a seasonably strong jet streak and PV anomaly rounding the base of a broad trough through the day on Thurs which will likely only contribute to periods multi-layered mid/high clouds through the morning and early afternoon. This cloud coverage may limit greater mixing potential and keep the prevailing northwest wind gusts below 25 mph and limit the otherwise favorable pattern for increased fire behavior. The better day for fire concerns likely comes on Fri where skies are mostly clear and will likely result in optimal momentum transfer through the deepening mixed layer in a very dry Canadian airmass already in place. Further drying from orthogonal downsloping winds will likely drop dew points into the teens to single digits through the afternoon. Northwest winds will likely be strongest in the morning to early afternoon hours (20-25 kts), but should gradually wane through the mid/late afternoon as surface high pressure builds closer to the southern Appalachians and weakens the pressure gradient.

Forecast confidence decreases rather rapidly Sun into next week as model guidance is struggling with how to handle the evolution of a mid/upper level low near the Four Corners Region Sun night into Mon, and how it interacts with a broad northern stream trough pivoting across eastern Canada and the Great Lakes Region. An ensemble forecast approach suggests this may however be a more active period as PW's increase to greater than an inch (70th to 85th percentile) and the southern Mid-Atlantic region located in a favorable position underneath the right-entrance region of the strengthening 250mb jet streak.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

As of 620 AM Tuesday...

VFR in the south and east, with lowering CIGS (MVFR to IFR) and higher chances of rain in the west and north late this morning into tonight.

VFR conditions will prevail overnight across central NC with plenty of cirrus through daybreak. MVFR ceilings should develop into the Triad ahead of an approaching warm front this morning. Some light rain is expected to develop in this region late morning and persist into the afternoon. This will likely aid in the development of in- situ CAD over the NW Piedmont and thus create a sharp gradient in ceiling heights between the Triad and Triangle in the afternoon, persisting into tonight.

To the south and east, VFR ceilings look likely through the afternoon and evening, with the potential for some fleeting MVFR ceilings around RDU. Additionally, light rain or virga may be possible throughout the day, but confidence is not high enough to include at any TAF sites. Outside of the Triad, southerly gusts up to 20 kts look possible, diminishing around sunset.

Outlook: Some light rain/showers will continue to move eastward across the region Tuesday night into Wednesday, bringing MVFR to LIFR ceiling and visibility restrictions. VFR conditions should return Wednesday afternoon through Friday with the passage of a strong cold front.

RAH WATCHES/WARNINGS/ADVISORIES

None.