textproduct: Raleigh

SYNOPSIS

A wedge front will remain quasi-stationary over the northwest Piedmont through early morning. A strong, polar front will sweep east across NC this afternoon into early evening. Cold high pressure will follow and build from northwestern Canada to the Middle Atlantic through Saturday.

KEY MESSAGES

- Periods of showers are expected this morning as weak waves traverse a wedge front this morning.

- A wedge front will remain in the NW for several more hours with low status and possibly some mist and fog in the Triad.

- A strong cold front will drive through the region this afternoon and early evening with gusty shifting winds and clearing skies.

- Very warm today (70s).

- CAA arrives tonight (30s to lower 40s for lows). The showers will be likely into the early morning hours as weak waves travel NE along the Piedmont wedge boundary. Rainfall will be around 0.10 to 0.30 of an inch in the Piedmont, lesser totals elsewhere. The main front will surge through the region this afternoon and early evening. The showers of the morning hours will move away with loss of upper support, with clearing skies prior to the fropa this afternoon. This will allow the temperatures to soar as we all break out into the pre-frontal SW-W flow. With partly sunny skies this afternoon, the highs should soar into the 70s for most areas.

CAA and much, much drier air will arrive on WNW winds this evening and tonight at 10-25 mph. The gustiness will be strongest in the NW Piedmont just in the rear of the cold front late this afternoon when winds may reach 35 mph. Lows will fall a good 30 to 40 degrees by 12z/Thu from today's highs. Lows 35-45 NW to SE.

KEY MESSAGES

- Very minimal fire weather concerns due to the cold temperatures.

- Dry air and breezy WNW winds at 10-20 mph will make it feel even colder, with partly sunny skies.

- Mainly clear and cold Thursday night. Lows 24-30 (wind chills 18- 24).

Expect a pressure gradient to continue to drive CAA into the region. Highs in the afternoon in the upper 40s to mid 50s NW to SE. Feels like temperatures in the upper 30s and 40s. There will be some stratocumulus and cirrus, but overall partly sunny becoming mostly sunny. Fire weather parameters of minimum RH of 18-28 percent with gusty winds suggest discussion with the NCFS. However, some wetting rain today and expected cold readings (sub-55 temperatures) essentially may negate the need for major concerns.

Clear and cold with lows in the 20s to near 30 (SE) Thursday night with high pressure approaching from the NW.

LONG TERM /FRIDAY THROUGH TUESDAY/

As of 110 AM Wednesday...

* Marginal Fire Wx concerns on Fri.

* A more active and wetter pattern is becoming increasingly likely early next week, although timing and amounts remain highly uncertain.

A tight surface pressure gradient will still be in place Fri between the strong surface high over the Mid-Mississippi Valley and the sub- 1000mb occluded surface low over Quebec. Northwest winds of 10-15 mph with gusts around 25 mph will be likely across much of the northern Piedmont and northern Coastal Plain through the afternoon hours. Despite cold temperatures throughout the day (40s) dew points are expected to further drop into the low teens to single digits and contribute to relative humidity values dropping below 30% by 12 PM. These conditions may result in a greater risk for increased fire danger, but will depend on the amount of rainfall that falls in the next 24 hours and resultant fine fuel moisture.

Confidence continues to increase in a more active and wetter pattern emerging Sun through Tues night. Ensemble guidance shows a positively-tilted trough axis between a lead northern stream wave lifting through the Great Lakes region and a trailing trough diving into the Four Corners region. PWAT values rise to well-above normal (0.75 to 1.25") on the southern flank of the trough across much of the Southeast and Mid-Atlantic regions. Timing uncertainty of these two waves is resulting in a long duration of precipitation chances in the forecast, but deterministic guidance suggest two separate rounds of better precipitation chances are more likely with a relative lull in between. The first wave, Sun into Sun night, only provides glancing and weak synoptic forcing with neutral H5 tendencies and weak WAA pattern, which should keep the upper-end rainfall totals (90th percentile around 0.5" in 24 hours) lower, comparative to the next system. This lead system will likely setup a an in-situ to hybrid CAD regime over the Carolina Piedmont, which should further persist with weak, but saturated, isentropic ascent in the 285-295K layer.

The next system will be driven by the trailing shortwave as it ejects over the southern Plains and through the Southeast early next week. There is a large spread in timing and amplitude of this feature, but will likely result in a Miller A surface low track pattern (single surface low originating in the Gulf and tracking across the Southeast and western Atlantic). With the lack of a favorable surface high location, this favorable pattern will likely result in a cold rain for the Carolinas with no p-type concerns at this time. The range in potential rainfall totals is noticeably much higher with this second system and may bring a much-needed, steady, and soaking rain to the area.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

As of 1250 AM Wednesday...

MVFR to IFR conditions are expected through the early morning today. Through 12z, IFR to LIFR ceilings are expected to move into the region with areas of showers spreading east.

Ahead of a cold front, a 45-50 kt jet is likely and should weaken as it moves across the region. Thus, LLWS was introduced at INT/GSO and is likely going to be weaker at RDU/FAY/RWI so was not included at those sites at this time.

VFR conditions will return by afternoon, however gusts of around 25-30 kt gusts everywhere appear likely. The wind will shift from the WSW to the WNW after the cold frontal passage.

Outlook: VFR conditions appear likely through at least Saturday, with the chance of rain returning Sunday ahead of another cold front.

RAH WATCHES/WARNINGS/ADVISORIES

None.