textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated for new Aviation Discussion.

KEY MESSAGES

1. Abundant surface moisture may allow formation of dense fog tonight that could impact the Wednesday morning commute. 2. Well above normal temperatures and mostly dry conditions through the weekend with rain chances possible by Sunday.

DISCUSSION

Key message 1: Abundant surface moisture may allow formation of dense fog tonight that could impact the Wednesday morning commute.

Now that we have the cold air damming wedge effectively eliminated, our attention turns to the possibility of locally dense fog developing overnight. The remnants of low cloud cover make this a tricky proposition, because the low clouds will often expand in the mid/late evening and work against fog formation. A light southerly flow has developed, but not to any great extent, calling into question any moisture advection that would favor fog. We also have some high thin clouds moving overhead. Guidance still suggests some dense fog potential over the NC foothills and some locations south of I-85. At this point, a Dense Fog Advisory seems unlikely.

Though a moist boundary layer will remain in place Wednesday, 925mb thermal advection turns neutral and sfc high pressure even more distant, so we will advertise scattering clouds and warming reflective of the spring-like pattern, with max temps in the lower-mid 70s.

Key message 2: Well above normal temperatures and mostly dry conditions through the weekend with rain chances possible by Sunday.

A strong Bermuda High, a pattern generally typical in the summer months, remains fixated off the Carolina coast and well over the region through at least Monday. Current guidance retains weak southerly/southwesterly flow and very slow moisture return through the end of the forecast period. The persistent high pressure keeps temperatures well above normal everyday and rain chances away until the weekend. Guidance has trended drier, but depicts an eastward shift of the high pressure. If this occurs, more moisture could advect into the region along the western fringe. This has the potential to increase rain chances on Saturday, though confidence remains low. By Sunday, model guidance lifts an area of low pressure across the northern Plains and drag a weak cold front towards the area, also increasing rain chances. Additionally, depending on when/if this front can make it into the CWA, there could be a low chance for thunderstorms. Will continue to monitor.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: The wedge has broken down as evidenced by the light SE to SW wind at most terminals this evening, and all terminals are presently VFR, but the low cloud deck did not completely mix out before sunset. In most cases, this means that the low cloud deck will expand once again during the mid/late evening, bringing the restriction back. The guidance indicates this happening more toward 06Z but it will probably happen sooner, so we reintroduce the MVFR to KCLT by 02Z and go from there. Similar to last night, the fcst takes the ceiling down to the lower end of MVFR but does not include any IFR, but that is a distinct possibility. The problem spot will probably be KHKY where the proximity to the river makes it most likely to drop to IFR or LIFR in the pre-dawn hours. The low cloud restriction should mix out by mid/late morning, after which we should have a stronger SW flow across the region. Fair weather cu looks like a good bet for the afternoon.

Outlook: Springlike weather pattern over the next several days. Cannot rule out patchy overnight fog/stratus. Another cold front may bring showers and associated restrictions for the weekend.

CLIMATE

RECORDS FOR 03-05

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 78 1955 20 1960 60 2004 5 1960 KCLT 84 1955 31 1960 62 1955 12 1960 1880 KGSP 80 1976 31 1960 61 2004 12 1960 1905 1976 1961

RECORDS FOR 03-06

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 78 1908 28 1960 58 1961 5 1960 KCLT 80 2022 33 1901 62 1961 10 1960 KGSP 79 1974 37 1948 63 1961 16 1960 1915 1901

RECORDS FOR 03-07

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 82 1974 23 1920 61 1956 15 1960 KCLT 85 1974 30 1899 63 2022 14 1899 1956 KGSP 83 1974 36 1920 62 1961 13 1901 1901 1956

RECORDS FOR 03-08

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 81 1974 23 1996 57 1921 8 1920 KCLT 84 1974 36 1989 59 1946 16 1920 KGSP 84 1974 35 1899 56 1921 14 1901 1899

RECORDS FOR 03-09

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 80 1974 22 1932 57 1964 8 1996 KCLT 83 2009 30 1960 62 1925 16 1996 1974 1921 1925 KGSP 85 2009 29 1960 60 2009 16 1996 1921

RECORDS FOR 03-10

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 76 1974 29 1932 58 1903 10 1996 1932 KCLT 82 1974 36 1924 59 1903 17 1932 KGSP 84 1974 39 1924 58 2009 17 1932 1997

GSP WATCHES/WARNINGS/ADVISORIES

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