textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for the 00z TAF issuance.

KEY MESSAGES

1. Well above normal temperatures linger through Friday before a strong cold front brings much cooler and below normal temperatures over the weekend. Frost may develop over portions of the North Carolina mountains Saturday night but confidence is low. 2. Gusty winds are expected in association with the cold front Friday into Saturday. Confidence on a Wind Advisory is low at this time. 3. Dry for most areas through early next week outside of some northwest flow rain showers behind the cold front Friday into Friday night.

DISCUSSION

Key message 1: Well above normal temperatures linger through Friday before a strong cold front brings much cooler and below normal temperatures over the weekend. Frost may develop over portions of the North Carolina mountains Saturday night but confidence is low.

Upper ridge continues building over the Southeast through Wednesday, lingering over the region through Thursday night. The ridge gradually retreats south and east on Friday ahead of an upper trough digging across the Midwest as it pushes eastward. This pattern will act to keep warm and well above normal temperatures around through Friday. Both highs and lows each day through Friday will end up around 10-15 degrees above normal for this time of year.

The aforementioned upper trough then digs southward towards the Carolinas over the weekend before another upper ridge builds over the region early next week. At the surface, a cold front will bring the strongest airmass change we have seen so far this fall, with highs behind the front expected to be roughly 20 degrees cooler on Saturday compared Friday. Highs over the weekend should end up around 5-10 degrees below normal, becoming a few degrees below normal Monday and near normal Tuesday as heights gradually build. Much cooler lows return starting Friday night behind the front, with Saturday night shaping up to be the coldest night of the forecast period. Despite much cooler temperatures Friday night, gusty winds will prohibit frost development. The frost potential will be better Saturday night into daybreak Sunday as the pressure gradient finally relaxes, allowing lighter winds to return. Frost would appear to be mainly confined to the North Carolina mountains at this time based on the current low temperature forecast. No major concerns regarding a potential freeze at this time as most locations will remain above freezing Saturday night. With lows expected to go on a warming trend starting Sunday night, frost concerns will be very low through the rest of the forecast period.

Key message 2: Gusty winds are expected in association with the cold front Friday into Saturday. Confidence on a Wind Advisory is low at this time.

Breezy W/SW winds will develop ahead of the cold front, becoming gusty as winds turn NW behind the front. For now, it appears that most locations will remain below Wind Advisory criteria (which starts at 45 mph) outside of the higher elevations in the northern North Carolina mountains. The LREF seems to agree with the northern mountains having the best chance to see advisory level gusts develop, showing a roughly 40-50% chance of gusts exceeding 45 mph. Will continue to monitor trends regarding wind gusts in the coming days to see if a Wind Advisory may be needed. Wind gusts should gradually diminish throughout Saturday as the pressure gradient relaxes.

Key message 3: Dry for most areas through early next week outside of some northwest flow rain showers behind the cold front Friday into Friday night.

Dry high pressure lingers over the region through Friday morning before the cold front sweeps across the forecast area Friday afternoon/evening. Northwest flow rain showers will develop behind the front Friday afternoon into at least Friday night, but could linger through early Saturday morning. Temperatures appear to remain warm enough behind the front for all liquid precipitation as the cold air will be chasing the moisture. Another area of dry high pressure builds in behind the departing front this weekend, lingering over the region through early next week allowing dry conditions to return area-wide.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Expect the dry, mostly clear, VFR conditions to continue thru the 00z TAF period. We will probably see another round of mtn valley fog and/or low stratus overnight and into the morning, but much like this morning, restrictions probably won't reach KAVL. Thus, KAVL remains VFR thru the period. Expect winds to go light and VRB to calm again tonight and remain that way thru the morning. They should pick up again from the S to SW outside the mtns tomorrow afternoon with speeds of roughly 5 kts.

Outlook: Mainly VFR conditions are expected thru early next week, outside of the potential for mtn valley fog and low stratus each morning.

CLIMATE

RECORDS FOR 10-13

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 83 1969 44 1907 63 2017 29 1917 1954 KCLT 91 1954 50 1977 68 1883 35 1964 KGSP 87 1954 54 1906 65 2017 29 1988 1954 1926

RECORDS FOR 10-14

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 82 1928 51 1907 64 1954 25 1988 KCLT 87 2021 56 1922 68 1883 32 2006 1940 1881 KGSP 86 1985 57 1907 67 1954 30 1988 1928

RECORDS FOR 10-15

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 86 1897 52 2002 60 2017 27 1907 1970 1928 KCLT 88 1985 53 2009 66 1985 30 2006 KGSP 86 1985 53 2002 65 1985 31 1907 1941 1970

RECORDS FOR 10-16

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 87 1897 49 1954 63 1928 29 1939 KCLT 87 1925 58 1937 68 1947 35 1939 1925 KGSP 85 1935 53 1937 67 1925 32 1907 1911 1892

GSP WATCHES/WARNINGS/ADVISORIES

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