textproduct: Raleigh

WHAT HAS CHANGED

* No appreciable changes

KEY MESSAGES

As of 203 PM Thursday...

1) Still cannot rule out a low-end severe threat this afternoon and evening as showers gradually taper off behind the front.

2) Next best chance for rain will come Sunday into Monday as a few waves of energy move through the region.

DISCUSSION

As of 203 PM Thursday...

KEY MESSAGE 1...Still cannot rule out a low-end severe threat this afternoon and evening as showers gradually taper off behind the front.

The cold front is presently located over the northern Piedmont and northern Coastal Plain, about to move through the Triangle here shortly. The front is expected to move through the remainder of our southern zones by early this evening, between 6 and 8 pm. Gusts behind the front may range from 15-20 mph, with an outside gust to 25 mph.

The main precipitation shield tied to the upper-level trough and associated isentropic ascent is about to exit the Triangle and Coastal Plain in the next few hours, with just isolated activity by early afternoon. Rainfall estimates so far from MRMS suggest several areas of 0.5 to 1.0 inch, with streaks of 1.25 to 2 inches over the southern Piedmont and northern Coastal Plain. An additional 0.1 to 0.25 inches of rain is possible before showers exit tonight.

As the surface cold front continues to move south, a redevelopment of some scattered showers and embedded storms is expected over the western and southern Piedmont, tracking into the Sandhills and portions of the southern Coastal Plain. An area of clearing is already evident on satellite imagery near Charlotte and this may aid some afternoon instability upwards of 250-500 J/kg of surface cape. With deep-layer flow still quite strong of 50-70 kts, cannot rule out that low-end damaging wind threat with any storms in the hours of 3 to 8 pm. While the SPC marginal risk covers our eastern Sandhills and southern Coastal Plain, we think that threat also exists over the southern Piedmont and western Sandhills.

Showers will come to an end in our south and east zones around 8 pm, with cloudy skies gradually clearing overnight as cool high pressure settles into the region. While widespread fog is not anticipated given some northerly stirring, it cannot be fully ruled out over portions of the Triangle and northern Coastal Plain, especially if winds become calm.

KEY MESSAGE 2... Next best chance for rain will come Sunday into Monday as a few waves of energy move through the region.

While the next best chance of rain will be Sunday and Monday, there is a small chance of isolated showers Saturday afternoon. However, the chance looks low as shortwave energy looks to split the region, with some energy passing to our north and more passing to our south. This would leave central NC as a relative minimum in rainfall. The best chance of rain should be in the Sandhills and southern Coastal Plain.

The better rain chances will come Sunday afternoon through Monday night as a frontal boundary to our south starts to lift north and merge with an approaching cold front from the west. There is still uncertainty within how early rain may fall within both ensemble and deterministic model data. Some guidance suggests that a few showers may start as early as Sunday morning, while other guidance keeps central NC mostly dry through the day on Sunday. This can be seen especially in the 50th percentile of 24 hour precipitation of each ensemble ending at 2AM Monday. The GEFS has around 0.1 to 0.4 in of rain in central NC, while the European ensemble only shows a few hundredths in the south with the rest of the region dry. The better rain chances will come Monday with the stronger frontal passage. This frontal passage could bring an additional 0.1 to 0.5 in of rain to the region. After this, the next chance of rain will come Wednesday into Thursday as another weak cold front moves through the region.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

As of 129 PM Thursday...

MVFR/IFR ceilings persist across central NC this afternoon as primarily stratiform rain exits east across the Coastal Plain. Some clearing has developed across the Foothill ahead of a cold front which has just passed through KRDU. High-res guidance continues to suggest a broken line of showers with embedded storms will develop in some capacity along the advancing front first near KINT/KGSO before advancing east-southeast into this evening. Not expecting thunder at KINT/KGSO or KRDU/KRWI, but can't rule an isolated stronger storm and associated gust at KFAY later today. Otherwise, some nnely gustiness is likely behind the frontal passage for a few hours this afternoon and evening, diminishing overnight.

Low-level saturation will take a while to dissipate, so expect MVFR ceilings to persist through much of the afternoon and evening at KRDU/KFAY/KRWI. All sites will largely lift to VFR tonight, although patchy fog and associated reduced visibility is possible early Friday morning (highest chances at eastern TAF sites). Otherwise, expect light winds and VFR conditions Friday.

Outlook: There will be also be another chance of showers and storms with adverse aviation conditions as another cold front moves across the region on Sunday into Monday.

RAH WATCHES/WARNINGS/ADVISORIES

None.