textproduct: Raleigh

SYNOPSIS

A front will move north as a warm front across NC and VA today, only to move south as a cold front again tonight. Cold high pressure will follow and ridge across the Middle Atlantic on Friday. The front will then continue to waver across the Carolinas ahead of a strong cold front that will sweep across the region on Monday.

NEAR TERM /THROUGH TONIGHT/

As of 335 AM Thursday...

* Unseasonably mild/warm

A shortwave perturbation in nwly flow aloft, now centered over nrn OH/nern IN, will progress across and offshore the srn Middle Atlantic through the morning-midday hours, as will a preceding low/mid-level WAA regime. A sub-tropical high over the Gulf, and ridge initially extending across the Plains and MS Valley, will otherwise break down and promote increasingly-zonal flow across the mid-latitudes by 12Z Fri.

At the surface, a ~1025 mb high now centered along the Middle Atlantic coast will drift offshore this morning. In return, sly flow that has already developed lightly across w-cntl NC early this morning, a warm front will retreat newd across NC and VA today. The front will then move swwd, in backdoor cold frontal-fashion, and across cntl NC tonight. Cold high pressure will follow and ridge across the Middle Atlantic later tonight-Friday.

Multi-layered ceilings and a lead area of scattered showers/ sprinkles, accompanying the aforementioned low/mid-level WAA regime and along the srn periphery of an area of electrified, elevated convection now progressing across OH, will progress ewd and out of cntl NC through midday. Partial clearing will result, with an associated mix of afternoon sun and clouds (more of the former over the srn Piedmont/Sandhills) that will favor another unseasonably mild/warm day, with temperatures mostly in the lwr-mid 70s and accompanied by swly surface winds that will strengthen and gust up to 20-30 mph during the afternoon.

The passage of the backdoor cold front tonight will be marked by an abrupt wind shift to nely, with a couple or so hour period of stronger CAA and mixing immediately behind it that will probably support additional wind gusts to around 20 or so mph. A band of post- frontal cloudiness and patches of light rain/sprinkles will follow the front swwd, with temperatures by Fri morning likely to range from mid 30s ne to mid/upr 40s sw.

SHORT TERM /FRIDAY AND FRIDAY NIGHT/

As of 400 AM Thursday...

An initially low-amplitude shortwave trough over the upr Great Lakes will amplify as it progresses ewd and across the Great Lakes and Northeast through Fri night, with associated glancing and weak height falls that will progress across cntl NC Fri.

At the surface, cP high pressure will ridge, from its 1030-1035 mb center over QC, swd and across the Middle Atlantic. Along its srn periphery, a front will become quasi-stationary over SC on Fri. Although mass fields support a nwd retreat of that front across NC Fri night, nocturnal cooling will likely cause associated warming to occur above a the surface inversion Fri night and consequently delay the realization of milder/warmer surface temperatures until Sat.

While Fri will be seasonably cool and generally cloudy, rain chances appear slim given the only glancing and weak influence of the shortwave trough progressing across the Great Lakes. A limited diurnal temperature range will result from the ridging and weak (mainly dry) CAD, with highs Fri centered in the mid 40s to mid 50s from north to south and Fri night lows mostly in the 40s.

LONG TERM /SATURDAY THROUGH THURSDAY/

As of 235 AM Wednesday...

Upper pattern: A mid-level ridge will briefly re-establish itself over the Deep South on Saturday ahead of a deeper trough that will dig down from Canada and move across the eastern US late Sunday into Tuesday. Nwly flow and rising mid-level heights aloft will spread east across central NC Wednesday into Thursday.

Saturday and Sunday: Guidance continues to trend slower with the arrival of the upper trough and strong sfc cold front early next week. As such, largely nwly flow aloft will promote dry conditions both Saturday and Sunday. Saturday continues to trend warmer with highs in the mid 60s to lower 70s. On Sunday, upstream perturbations associated with the approaching upper trough will promote a bit more cloudiness. Additionally, an area of high pressure will drift east across the Mid-Atlantic and possibly extend nely flow down into central NC. This setup would promote cooler highs on Sunday in the upper 50s (N) to mid 60s (S).

Monday through Thursday: Most guidance now has the front moving across central NC later Monday afternoon, with CAA ramping up later Monday night. As such highs on Monday have trended much warmer with solid swly flow ahead of the front pushing highs in the mid to upper 60s. Associated rain chances will peak late Wednesday afternoon and into the early overnight period. However, ensembles continue to highlight low QPF with this system (95th percentiles highlight only a few tenths of an inch to maybe a half inch through Tuesday morning). Still expecting some stronger post-frontal nwly gusts of 20 to 30 mph Monday afternoon into the early overnight period Monday night. Temps will drop into the mid to upper 20s early Tuesday morning. Highs on Tuesday will struggle to reach lower 40s while overnight lows drop into lower to mid 20s.

Low-level thicknesses remain lower through the end of the week with a potentially re-enforcing cold front Friday into Saturday. As such, current signs show the potential for a chilly start to the new year.

AVIATION /12Z THURSDAY THROUGH MONDAY/

As of 650 AM Thursday...

VFR conditions are expected through at least this evening, but with ceilings as low as 4-7 thousand ft at times and patches of light rain or sprinkles that may result from those VFR ceilings this morning. The nwd retreat of a surface warm front into VA today will cause light sly surface winds this morning to veer and strengthen/ become gusty into the upr teens/lwr 20s kts from around 15-16Z through sunset, then diminish. The front will return swwd as a cold front tonight, during which time a wind shift to nely will be accompanied by gusty surface winds for a couple of hours immediately following the passage of the front. A band of post-frontal, 2500- 5000 ft ceilings will also accompany the front and move swwd and across cntl NC tonight, lowest and with the highest probability of MVFR ceilings at GSO and INT by ~07-08Z.

Outlook: The aforementioned frontal zone will continue to waver across NC through the weekend, with related periods of mostly MVFR ceilings most likely on Fri and again Sun-Sun night. A stronger cold front will sweep across the region with a chance of rain and additional flight restrictions on Mon.

RAH WATCHES/WARNINGS/ADVISORIES

None.