textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Minor changes to precip amounts and temperatures late in the week.

The aviation discussion was updated to reflect the 12Z TAF issuance.

KEY MESSAGES

1. A summer-like pattern will continue through mid-week, with above normal temperatures and little chance of deep convection until Wednesday afternoon as a front approaches. 2. A cold front brings better rain chances for the latter part of the week and into the weekend, but drought relief will be limited.

DISCUSSION

Key message 1: A summer-like pattern will continue through mid-week, with above normal temperatures and little chance of deep convection until Wednesday afternoon as a front approaches.

As advertised, we are still on track for our Summer preview for the next two to three days as a building mid/upper ridge/anticyclone over the East Coast supports a Bermuda High. No big surprises here in the new guidance. Temps will generally run 7-12 degrees above normal, with highs pushing the lower 90s in many spots east of the mtns, but not nearly enough to challenge records. Still no indication that dewpoint will be high enough to make apparent temps any warmer than air temps. The CAMs keep the fcst area dry today and hold very little promise for mountain convection on Tuesday. Thus, we shall bake as if in an oven.

By Wednesday, the upper anticyclone moves off to the east and a wave in the nrn stream will flatten out the eastern ridge, so a cold front is still expected to move toward the mtns from the OH Valley. The latest batch of models suggests this boundary will be farther away than expected, however, so the chances of getting any shower activity east of the mtns are poor. The new fcst will have a gradient in precip chance over the Escarpment Wednesday afternoon, with a strong diurnal signal, so Wednesday night looks quiet. This period is beyond the CAMs, so it is possible the precip chances might ultimately improve, especially if something gets organized to the west and moves in late in the day.

Key message 2: A cold front brings better rain chances for the latter part of the week and into the weekend, but drought relief will be limited.

The medium range part of the forecast remains something of a moving target because of uncertainty regarding the passage of the cold front and whether or not the boundary will ever truly move through the fcst area. Some of the guidance already starts to rebuild the eastern upper ridge on Friday into the weekend, which could lift whatever remnant there was back north as a warm front by Saturday. Either way, Thursday and Friday look...unsettled...so likely/categorical precip probs are still in order. Weak cold air damming remains apparent for Friday, maybe with a stronger signal than yesterday, but it would be brief as the parent high would move away Friday night and we'd get back into a warm sector for Saturday. So, after one more warm day on Thursday, temps cool down to something roughly five degrees below normal for Friday because of extensive clouds and some precip, then it's a return to normal for the rest of the fcst period. The weekend looks like above climo precip probs. For the time being, the chances of getting more than an inch of rain on any given day is low, but at least it looks like the drought would not get any worse through that period. The risk for severe storms appears to be low.

AVIATION /12Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Continued VFR at all terminals over the next 24-36 hours. A few orphaned patches of VFR-level convective cloud debris were noted on satellite imagery over the mtns and Upstate SC. Otherwise, a light S wind will continue through mid/late morning. We should pop up a few stratocu with daytime heating. Deeper mixing this afternoon will raise wind a bit from the S to SW, but gusts are not yet indicated. More clear sky and variable wind is expected after sunset.

Outlook: VFR to persist through mid-week, except perhaps 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.