textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

The forecast has trended a bit drier for the first half of the week.

KEY MESSAGES

1. Our area should remain mostly dry through the first half of the week. Diurnal shower and thunderstorm chances increase for the latter half of the week with temperatures remaining above normal for mid-September.

DISCUSSION

Key message 1: Our area should remain mostly dry through the first half of the week. Diurnal shower and thunderstorm chances increase for the latter half of the week with temperatures remaining above normal for mid-September.

In the wake of a weak frontal passage, we could see a few showers and maybe an isolated thunderstorm or two this afternoon/evening. Otherwise, the weather should be mostly quiet with temperatures roughly 3 to 6 degrees above normal.

A stout upper shortwave is expected to pass to our north on Monday, helping to push a back door cold front southward across our area. The model guidance continues to show little in the way of response wrt the fropa. This makes sense given the weak cap and minimal CAPE across the region Monday afternoon/evening as it moves through. On Tuesday, broad upper ridging spreads over the Southeast from the west and persists thru mid-week. The upper ridge will help support sfc high pressure that migrates eastward from the lower Great Lakes to New England from late Monday through Tuesday. On Wednesday, the sfc high gets pushed off the New England Coast by robust low pressure tracking across eastern Canada. Brief, weak cold air damming tries to develop on Tuesday, however a lack of moisture in the light ELY low-level flow will likely produce little in the way of precipitation. In addition, the expected lack of persistent cloud cover thru the day should allow high temperatures to top-out near, if not a few degrees above normal. If better cloud cover lingers for longer, fcst tempera- tures could be too warm. For the second half of the week, a frontal boundary stalls just to our north while a weak surface low tries to develop somewhere off the coast of south Florida. At present, the deeper moisture associated with the frontal bndy appears to remain mostly over the mtns each day, suggesting a chance of diurnal showers and storms each day Thursday thru Saturday with temperatures remaining 1 to 2 categories above normal for mid-September.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

At KCLT and elsewhere: Expect mostly dry, VFR conditions to prevail thru the 18z TAF period. Most of the latest guidance suggests another round of mtn valley fog and low stratus overnight, but it's unclear whether it will reach KAVL. Winds will favor a NWLY direction at KAVL overnight, but they will be weak and could be more VRB at times. For the time being, I have 5sm visby from 10 to 13z at KAVL. Otherwise, expect mostly few high clouds thru the period with winds becoming light and VRB (or at times favoring a NW direction) at most sites later tonight. Winds will pick up from the N/NE tomorrow afternoon with speeds in the 5 to 10 mph range. KAVL will likely see some low- end gusts thru the early evening with winds becoming light later tonight. Winds at KAVL will favor a NW direction tomorrow.

Outlook: Mostly dry conditions are expected to persist through the middle of the week. Shower chances and their associated restrictions increase later in the week.

GSP WATCHES/WARNINGS/ADVISORIES

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