textproduct: Raleigh

WHAT HAS CHANGED

* A Frost Advisory may be needed tonight with lows over the Piedmont and northern Coastal Plain in the low to middle 30s.

* Patchy ground fog this morning, especially near bodies of water, should disperse after sunrise.

KEY MESSAGES

As of 1232 AM Saturday...

1) Areas of frost will be possible Sunday morning.

2) A dry stretch of weather well into the middle of next week as temperatures gradually moderate. A pattern shift looks to take hold late next week, though the details are still uncertain.

DISCUSSION

As of 1232 AM Saturday...

KEY MESSAGE 1... Areas of frost will be possible Sunday morning.

Chilly high pressure over the Mid MS valley today will migrate into the TN valley tonight. While not in the most favorable position to support strong radiational cooling, winds should still go calm after sunset as the pressure gradient relaxes, from NW wind gusts of 15-20 mph this afternoon to light WNW overnight. The NBM probabilities for 36 degrees or lower range from 60-90 percent across the central and northern Piedmont into the northern Coastal Plain. This roughly covers an area along and north of US-64, though excluding most of the Triad and Triangle urban centers due to the urban heat island. Regardless, a Frost Advisory may be needed tonight into Sunday morning over these areas as lows dip into the low to middle 30s, except upper 30s to around 40 in urban areas and the Sandhills to southern Coastal Plain. After collaborating with neighboring WFOs, we decided to let the day shift take a closer look before issuing any products.

KEY MESSAGE 2... A dry stretch of weather well into the middle of next week as temperatures gradually moderate. A pattern shift looks to take hold late next week, though the details are still uncertain.

Northwest flow at mid-levels this weekend will support near to slightly below normal temperatures in the low to middle 60s. Guidance shows quasi-zonal flow taking over early to middle of next week, which should allow for moderating temperatures ranging from the upper 60s to low 70s. This stretch of weather is going to be dry with limited moisture return and a lack of systems tracking through the region.

The period from Thursday into Saturday of next week is still highly uncertain, however is starting to indicate a prominent pattern shift. Much of the guidance is in decent agreement that as ridging develops across the western US mid to late week, this allows for deep troughing to set up over the eastern US. The result is likely a Continental Polar airmass, which could bring our true taste of late fall. The 540-dm thickness line drops in some solutions as far south as GA and 850-mb temperatures drop below freezing, supportive of a widespread freeze at some point next weekend. The also interesting aspect to the pattern is that some ensemble cluster solutions, including some AI members, show an area of low pressure tracking from the TN valley to off the Mid-Atlantic coast Thursday into Saturday. Where that tracks is highly uncertain at this point, but could bring rain to the region and possible light snow to the Appalachians.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

As of 1232 AM Saturday...

A few areas of dense fog and low stratus are currently located over central NC. This is likely to remain a hazard over the next few hours until winds start to pick up and drier air moves into the region from the north, which will allow the fog/stratus to scatter out and lift. The most likely TAF sites to be impacted remain to be RWI, with RDU and FAY with a non-zero risk. Most sites that are currently impacted are LIFR with sub-1SM visibilities and ceilings between 100-400 ft. Additionally, a few hours of low-end gusts may be possible in the morning into the afternoon, with the best chance in the Triad. Otherwise, VFR conditions are expected to prevail.

Outlook: VFR conditions are expected through the remainder of the TAF outlook period. A couple reinforcing cold fronts will bring wind shifts and perhaps some gusty winds Tuesday night into Wednesday.

RAH WATCHES/WARNINGS/ADVISORIES

None.