textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Precipitation chances have trended higher for the coming weekend.

Updated the aviation discussion for the recent 06z TAF issuance.

KEY MESSAGES

1. Patchy frost is expected to develop by dawn across portions of the NC mountains and foothills. A Frost Advisory is in effect for those mountain zones that were not turned off during the most recent freeze. 2. Dry high pressure is expected to persist over our region through at least Friday with temperatures climbing back above normal. Rain chances increase this weekend.

DISCUSSION

Key message 1: Patchy frost is expected to develop by dawn across portions of the NC mountains and foothills. A Frost Advisory is in effect for those mountain zones that were not turned off during the most recent freeze.

A stout upper ridge remains centered just to our west and extends all the way to the Great Lakes, while a 1030mb sfc high centered just to our north continues to support weak cold-air damming across the western Carolinas. Below-normal temperatures and light winds overnight and into Mon morning should allow for patchy frost to develop across the NC mountains, and some parts of the NC foothills along the I-40 corridor. Although coverage is still expected to be limited based on the current temperature fcst, low temperatures may end up bottoming-out lower than expected under the ideal radiational cooling conditions currently in place. As a result, a Frost Advisory remains in place from 2 AM until 8 AM Monday morning for those zones across the NC mtns that have not already been "turned off" for the cool season based on a prior freeze. This includes most of the mtns south of I-26, as well as Burke and Caldwell Counties and eastern McDowell County, along the I-40 corridor.

Key message 2: Dry high pressure is expected to persist over our region through at least Friday with temperatures climbing back above normal. Rain chances increase this weekend.

The dry weather is expected to continue through the work week across our area. A stout upper ridge remains nearly stationary over the MS River Valley to our west. The resulting blocking pattern is expected to gradually dissipate over the next few days, however the Southeast will remain under broad upper ridging through the end of the week. At the surface, broad high pressure continues to linger over the Southeast as profiles reflect a fairly deep dry layer of air across the region. On Tuesday, another cP airmass will settle over the NE, reinforcing the low-level dry air and bringing marginally cooler temperatures for Wednesday. Nonetheless, temperatures are expected to climb back above normal by the end of the week as the high shifts eastward and off the Atlantic Coast.

Another reinforcing/back-door cold front is expected to arrive over the weekend and possibly re-establish some amount of cold-air damming across our area. This coupled with the breakdown of the upper blocking pattern mentioned above, may allow for an increase in low-lvl isentro- pic ascent across our area and produce some showers over the weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Very light N to NE winds this morning when not calm. Conditions still appear favorable for brief valley/river fog, affecting KAVL and KHKY with TEMPOs. Winds are expected to remain mainly in the 4-7 kt range today, still mainly N to NE. Periods of calm are expected around the area tonight, with only a few cirrus seen. Valley/river fog can't be ruled out tonight, but confidence remains low and any fog would most likely be after 06z Tue anyway.

Outlook: Mostly VFR conditions are expected through the work week. Mountain valley fog and low stratus will be possible each morning. Moisture appears likely to increase over the weekend.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...Frost Advisory until 8 AM EDT this morning for NCZ051-052-058- 059-062>065-501>504-506. SC...None.