textproduct: Raleigh

WHAT HAS CHANGED

As of 230 PM Monday...

* The cold front expected to move into the area Fri/Fri night may become quasi-stationary across the region over the weekend, however confidence in the finer details remains uncertain.

KEY MESSAGES

As of 230 PM Monday...

1) Patchy dense fog possible Tue morning

2) Temperatures will moderate through Friday. A cold front will move into and across central NC Friday/Friday night, potentially bringing some passing showers with it.

DISCUSSION

As of 230 PM Monday...

KEY MESSAGE 1... Patchy dense fog possible Tue morning

A combination tonight of clear and calm (or nearly so), and also residual low-level and soil moisture, should favor the development of radiation fog overnight-Tue morning. It should be noted that despite this relatively favorable environment, HREF probabilities for visibility restrictions less than one half mile during that time have decreased from 40-75% to 25-60%, between 00Z and 12Z/16th model cycles. As such, fog coverage of "patchy" versus "areas of" were retained in the NDFD for this forecast cycle.

KEY MESSAGE 2... Temperatures will moderate through Friday. A cold front will move into and across central NC Friday/Friday night, potentially bringing some passing showers with it.

Aloft, the sub-tropical ridge will flatten as it moves across the region Wed-Fri, with some weak disturbances traversing the ridge Thu/Thu night. Meanwhile, a nrn stream s/w will track ewd across the nrn Plains and into the upr MS Valley, while a trailing s/w moves across the Intermountain West. However, there are still significant model differences wrt the strength and track of these disturbances. At the surface, as the high shifts ewd over the Atlantic, warm sly return flow will prevail across the area. A warm front will lift nwd across central NC on Wednesday, perhaps getting hung up across the nrn Piedmont and/or nrn Coastal Plain as high pressure ridges swd across the mid-Atlantic Wed night/Thu. The warm front should finally lift out of the area by Thu night as the surface low occludes and lifts newd across the wrn Great Lakes. The attendant cold front will gradually become more W-E oriented across the region while the parent low occludes and a secondary low tracks ewd along the front.

Temperatures will moderate from Wed-Fri, with highs ranging from around 70 degrees along the VA border to upper 70s across the south by Friday. Along the warm front with the weak disturbances aloft Thu/Thu night, there could be some light rain, primarily along the VA border, otherwise the better chance for a shower or two will be Fri/Fri night as the front moves into the area from the NW. However, given the continued uncertainty, confidence on chances, coverage, and amounts remain low at this time.

Over the weekend: The surface front may linger across the area through Sat/Sat night, however there is a good deal of forecast uncertainty wrt the front and potential low developing/moving along it. There are also significant differences between the medium-range operational model solutions wrt the aforementioned trailing s/w and how it evolves as it moves ewd across the CONUS. These differences will have implications for the weather across central NC, thus the confidence in the finer weather details for Sat/Sun is low at this time.

AVIATION /18Z MONDAY THROUGH SATURDAY/

As of 115 PM Monday...

Moist, nly flow, around a pair of coastal lows moving away from the middle Atlantic coast, will maintain MVFR stratocumulus ceilings at RWI for another couple or so hours. Some lingering, nely surface gustiness will be possible through the same time at all sites, before those winds lessen and probably become calm by this evening. A combination of clear and calm tonight, and also residual low-level and soil moisture, should favor the development of radiation fog and ceilings overnight-Tue morning.

Outlook: A good chance of areas of fog and stratus will result again Wed morning, with MVFR ceilings from the latter that may linger through early afternoon. After a risk of low-level wind shear Tue night-Wed morning, swly surface winds will strengthen and become gusty through the day Wed, particularly in areas where clearing and deeper mixing materialize.

RAH WATCHES/WARNINGS/ADVISORIES

None.