textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Precip chances have been raised for a longer period of time late in the week.

The aviation discussion was updated to reflect the 06Z TAF issuance.

KEY MESSAGES

1. A summer-like pattern will be in place through mid-week, with above normal temperatures, increasing humidity, and spotty diurnal convection expected. An isolated severe thunderstorm will be possible in the afternoon and evening each day. 2. A cold front will bring better rain chances mid to late week, but rainfall amounts are expected to remain light any drought relief will be limited.

DISCUSSION

Key message 1: A summer-like pattern will be in place through mid-week, with above normal temperatures, increasing humidity, and spotty diurnal convection expected. An isolated severe thunderstorm will be possible in the afternoon and evening each day.

The latest guidance remains consistent with showing an early summer pattern developing across the region for the first half of the week. A mid/upper ridge will build along the East Coast today and an upper anticyclone should form off the Mid-Atlantic tonight, in response to the mid/upper trof digging over the western CONUS. The eastern ridge will hold a Bermuda High in place through at least Tuesday night. The flow around the Bermuda High will bring some summer-like warm temps to the region beginning today and then continuing through at least Tuesday and into Wednesday. Temps will generally run about ten degrees above normal, which means highs in the upper 80s to lower 90s east of the mtns and in the mtn valleys. It will feel hot, but not overly oppressive, because the air mass will remain relatively dry, and thus we should not approach heat advisory criteria. Record highs are probably not going to be reached, either.

Being a summer-like pattern, naturally our attention turns toward the chances of pulse-severe storms. Today might be the most interesting day of the string because of the presence of a remnant elevated mixed layer at mid-levels, seen as the layer of steep lapse rates above 8 deg C/km, which would lend itself to better hail chances in any storms that develop. However, fcst soundings continue to show a formidable cap across the region that would be very difficult to break even with differential heating. The HRRR keeps the lid on the convection, but other CAMs develop some storms to the west where the cap isn't as strong, and then propagate them eastward into our region. For now, a small precip prob will be kept over parts of southwest NC and northeast GA. We will monitor developments in the HRRR. Monday will be kept dry as the 00Z HRRR fails to develop any showers. The CAMs don't go out far enough to shed any light on Tuesday.

Key message 2: A cold front will bring better rain chances mid to late week, but rainfall amounts are expected to remain light any drought relief will be limited.

The latest guidance continues to show a de-amplification of the upper pattern during the middle part of the week, which allows a cold front trailing down from low pressure moving across eastern Canada to drop in from the northwest and over the mtns for Wednesday afternoon. Prospects for rain are holding up thus far as more of the guidance suggests the front will stall across our region into Thursday, then possibly slipping southward Thursday night. Precip probs ramp up to a respectable likely/categorical from Wednesday night through the first part of the weekend. Unfortunately, the ensemble guidance still shows that precip will be less than an inch over a 24 hour period, so any meaningful drought relief appears to be unlikely at this time. Still, a several day period of clouds and numerous showers won't hurt. Severe weather appears to be unlikely at this time. The temp forecast will be tricky as there are some signals for weak cold air damming mainly on Friday, but it should be short-lived. The passage of the front should bring temps back down to the cool side of normal for Friday and next weekend.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

At KCLT and elsewhere: VFR at all terminals through the period, with mainly just high cloudiness overnight into Sunday morning. Wind should stay calm or light/var overnight, then come up from the S to SW with some mixing during the middle part of the morning. We should have a few high based stratocu today, then sky goes mostly clear again tonight with more light/variable wind. Can't rule out a few showers over northeast GA and the southwest mtns.

Outlook: VFR to persist through mid-week, except in mountain valleys, where patchy morning fog/low stratus may develop each morning. An active cold front may bring restrictions associated with convective precip by late week.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.