textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for 00Z TAFs.

KEY MESSAGES

1. Breezy with well above normal temperatures continuing. Spotty light rain possible Wednesday across the mountains. 2. Well above normal temperatures are forecast late in the week, with record high temps possible Friday. 3. A frontal system will likely bring another round of weekend rain, followed by much colder temperatures and northwest flow snow showers early next week.

DISCUSSION

Key message 1: Breezy with well above normal temperatures continuing. Spotty light rain possible Wednesday across the mountains.

A shortwave ridge axis over the area tonight slides eastward on Wednesday as some weak short wave energy moves through the flow. At the surface, high pressure will slide east of the area with allowing for increasing southwesterly flow. This will lead to increasing low level moisture and weak isentropic lift. Gusty winds will diminish across the lower elevations early this evening, but will linger across the higher elevations through late this evening. Expect increasing cirrus through late this evening with lower clouds moving in overnight into daybreak Wednesday. Lows tonight will be around 15 degrees above normal thanks to increasing cloud cover. Cannot rule out some spotty light rain over the mountains on Wednesday, but any precip that manages to develop will be very light. Gusty southwest winds return Wednesday while cloudy skies remain overhead. Highs Wednesday afternoon will end up 10 to 15 degrees above normal thanks to low-level southwest flow and despite cloudy skies.

Key message 2: Well above normal temperatures are forecast late in the week, with record high temps possible Friday.

The axis of a broad long wave trough will gradually move from the Rockies to the Great Plains Thu through Fri, with the core of the upper jet and underlying baroclinic zone remaining west=>north of our area until at least Friday. The first in a series of mid-level speed maxima is expected to result in activation of the baroclinic zone, along with a broad warm advection response across our area Wed night into Thu, warranting mostly token chance PoPs through this time frame, with little in the way of significant rainfall expected. Following quickly on the heels of the initial speed max, the next one is forecast to nudge the leading edge of the baroclinic zone into the CWA by the end of Friday, with perhaps better chances for showers during the daylight hours Friday...and in fact, likely PoPs are forecast across much of the area. Nevertheless, rainfall amounts through Friday are expected to be unimpressive to say the least. Therefore the larger story through the end of the work week will be the very toasty conditions expected in the warm sector regime southeast of the frontal zone. Forecast temperatures Wed night through Friday are 15-20 degrees above normal. Min temps will be within a couple of degrees either side of where maxes should be for this time of year, while record daily highs will be in jeopardy at all three climate sites on Friday.

Key message 3: A frontal system will likely bring another round of weekend rain, followed by much colder temperatures and northwest flow snow showers early next week.

Friday night: A mid-level speed max moving east across the southern Great Lakes, along with a compact upper low diving southeast out of the Northern Plains will conspire to carve out a rather deep, albeit progressive trough across the East by early next week. Associated cyclogenesis is expected along a baroclinic zone draped across our region Fri night into Saturday, with PoPs ramping up to 50-60% across the CWA late Friday night into Saturday. Depending upon the eventual location and track of a cyclone, a locally excessive rainfall threat...perhaps even a small severe storm threat could eventually materialize, as there is likely to be some weak buoyancy in the warm sector. Having said that, model signals for either threat are not at all strong at this time. Either way, this does appear to be another event that should put at least a small dent in the ongoing drought conditions.

As cold advection surges through the area Sunday through early Monday, a moist northwest/upslope flow is expected to result in at least scattered mountain snow showers, with a good chance for minor accumulations across the usual Tennessee border areas. Temperatures will otherwise cool significantly late in the weekend, with maxes forecast to be near-normal on Sunday, followed by temps of 5-10 degrees below climo Sunday night into Monday.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: VFR through tonight with MVFR cigs developing across most of the terminals around daybreak Wednesday. MVFR cigs will linger through the early afternoon hours before lifting back to VFR by roughly 19Z. Guidance has backed off on MVFR cigs at KAVL so omitted this from the 00Z TAF. Wind direction will be S/SW through the period, with gusts returning on Wednesday. Gusts from 18-25+ kts can be expected through the late afternoon hours before gusts gradually decrease during the evening hours.

Outlook: Restrictions may return late Wednesday night into Thursday morning as guidance shows a round of patchy fog and low stratus developing. Rain and associated restrictions may return to the area Thursday and Friday but chances look more better over the weekend.

CLIMATE

RECORDS FOR 02-19

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 72 2014 16 2015 54 1951 3 2015 KCLT 76 2014 26 2015 55 1961 8 1958 1939 KGSP 75 2014 30 2015 55 1961 9 1958 1916 1900 1900 1911

RECORDS FOR 02-20

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 75 1939 26 1908 54 2018 4 2015 KCLT 77 2014 31 2015 59 1939 7 2015 1890 KGSP 75 2014 33 2015 57 1939 9 2015 1986

GSP WATCHES/WARNINGS/ADVISORIES

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