textproduct: Raleigh

WHAT HAS CHANGED

* The greatest risk for short-track tornadoes appears to be from the Triangle to the north and east, roughly from Raleigh to Goldsboro to Rocky Mount/Henderson and northeast into Roanoke Rapids.

* The main severe threat is favored from 11 AM to 6 PM today.

KEY MESSAGES

As of 308 AM Sunday...

1) Scattered to locally numerous showers/storms late this morning into the early evening hours will be capable of brief, short-track tornadoes and strong to severe wind gusts.

2) Much of next week will be unseasonably warm, before a significant cooldown next weekend. Little if any precipitation is expected through the period.

DISCUSSION

As of 308 AM Sunday...

KEY MESSAGE 1... Scattered to locally numerous showers/storms late this morning into the early evening hours will be capable of brief, short-track tornadoes and strong to severe wind gusts.

The remnants of Isaias are presently across eastern TN. With time, this area of low pressure will track into the Mid-Atlantic this evening and eventually off New England overnight tonight. A secondary area of low pressure is forecast to develop near Charlotte this morning, tracking into the NW Piedmont this afternoon before reaching central VA this evening. As this does so, a warm front presently across SC will lift north this morning, ahead of a strong cold front that will sweep through this afternoon and early evening.

Overall, there has been minimal change to the going forecast through tonight. The main uncertainty lies in overall coverage of scattered showers and storms. SPC has maintained a Level 2 Slight Risk for eastern areas of central NC, from the Triangle/Sandhills eastward and a Level 1 Marginal Risk across the western and southern Piedmont. The latest HREF/REFS solutions are indicating a more focused tornado threat across the far northeast Piedmont into VA, closer to the triple point and area of low pressure. However, in this environment with strong deep-layer shear and clockwise turning, a brief tornado threat will exist nearly anywhere in central NC.

The greatest severe risk is favored from 11 AM to 6 PM today, based on a suite of ensemble/model guidance and the timing of the cold front/dry slot. Ahead of the front, a moisture-rich environment will exist with low/mid 70s dewpoints, supporting 1000-1500 J/kg of MLCAPE. This axis of instability and shear overlaps most favorably from the Triangle/Sandhills into the central/northern Coastal Plain. CAM solutions indicate a broken band of showers and storms moving east-northeast in this time frame. Although an isolated tornado could happen anywhere, the greatest risk for short-track tornadoes appears to be from the Triangle to the north and east, roughly from Raleigh to Goldsboro to Rocky Mount/Henderson and northeast into Roanoke Rapids. In this region, forecast soundings indicate long curved hodographs supportive of discrete supercells. Outside of the tornado risk, strong to severe wind gusts will be possible across all of central NC. The severe threat should greatly diminish after 6 PM as activity races NE into the Mid-Atlantic coast.

KEY MESSAGE 2... Much of next week will be unseasonably warm, before a significant cooldown next weekend. Little if any precipitation is expected through the period.

Broad mid/upper ridging over the Southeastern US (in between troughing over the North Atlantic that will absorb the remnants of Isaias and a closed low over the Intermountain West) will bring mostly sunny and dry weather to central NC for much of the upcoming workweek. At the surface, a low will track east from the Great Lakes into northern New England from Tuesday into early Wednesday, dropping a backdoor cold front southward into the Mid-Atlantic. Southerly flow ahead of the front will bring increasing temperatures to start the week, with highs in the upper-70s to lower-80s on Monday and lower-to-mid-80s on Tuesday. Due to a slower trend with the low's translation eastward, the front now doesn't look like it will cross central NC until Wednesday night or Thursday. This results in a much warmer forecast for Wednesday and potential record or near record highs, which are now expected to be in the mid-to- upper-80s, and lows in the lower-to-mid-60s. Thursday's temperatures will depend on the exact timing of the front, but they should turn at least a bit more seasonable, albeit still warmer than normal. The front will be moisture-starved and devoid of any upper support for precipitation with the ridge in place, so it should be mainly dry with just some associated cloud cover.

A more vigorous northern stream shortwave will then dive down from Canada in the northern Plains and Great Lakes region late in the week and potentially interact with the Western US trough, which should help suppress the Southeast US ridge over the weekend. Guidance is in better agreement that the low will help lift the aforementioned boundary back north as a warm front on Friday, but significant differences in the pattern still exist, with the GFS continuing to show a phasing solution that results in a much deeper/slower trough (and associated surface low) compared to the ECMWF. The low will drag a much stronger cold front through central NC, but the exact timing is still uncertain, sometime on Friday or Saturday. Regardless the best forcing looks to be well to our north so any associated precipitation would be light, and POPs are only slight chance at best. A significant cooldown to below-normal temperatures appears likely behind the front as Canadian high pressure builds in, and patchy frost may even be a concern on Saturday night and/or Sunday night.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

As of 146 AM Sunday...

A mixture of LIFR/IFR conditions are expected to dominate the near- term of the TAF period. These conditions are likely to remain in place until 15-18z, slowest to rise to MVFR in the Triad terminals (GSO/INT) and earliest at FAY. Isolated to scattered showers are around the region, most focused over the Triad terminals. This should remain the case until mid-morning, though cannot rule out some brief heavy showers move through any one terminal prior to that. Outside of any showers, a moist low-levels will promote fog development, with the highest confidence at GSO/INT early this morning. However, cannot rule out patchy LIFR/IFR visbys anywhere. An area of low pressure will track through the region this afternoon, with a corresponding cold front. Most high-res model solutions indicate a somewhat broken line of showers and storms tracking eastward ahead of the front roughly between 15-21z. Confidence was high enough to include a TEMPO group for storms, though the most coverage may end up being near RDU/FAY/RWI. As the front approaches, MVFR will lift to VFR and prevail through the end of the TAF period. Gusty winds will exist times, starting out east- southeast and switching around to west-southwest late in the period.

Outlook: A return to VFR conditions is expected Sunday evening, persisting through much of the upcoming week.

RAH WATCHES/WARNINGS/ADVISORIES

None.