textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

The aviation discussion was updated for the 12Z TAFs.

KEY MESSAGES

1. Fire weather concerns continue amid a dry and stagnant weather pattern. A Fire Danger Statement has been issued again for Wednesday afternoon for all of western North Carolina and northeast Georgia. Critically low relative humidity and breezy conditions are likely to occur each of the next several afternoons. 2. Hot and dry through Saturday with high temperatures near daily records. A cold front may bring some rainfall to our area on Sunday, but any accumulations will likely be too small to improve drought conditions. Near-normal temperatures are expected early next week.

DISCUSSION

Key message 1: Fire weather concerns continue amid a dry and stagnant weather pattern. A Fire Danger Statement has been issued again for Wednesday afternoon for all of western North Carolina and northeast Georgia. Critically low relative humidity and breezy conditions are likely to occur each of the next several afternoons.

Continued low-level southwesterly flow from a weak Bermuda surface ridge will continue through Thursday. Despite the typical moisture return in this regime, deep boundary layer mixing will continue to tap into very dry air aloft, which will cause dewpoints to mix out during peak heating. Combine that with early Summer-like temperatures and RH values will dip between 25-30% each afternoon. Winds at the top of the boundary layer (<=800mb) will be strong enough to produce breezy conditions (gusts up to 15-20 mph) as well, especially Thursday when the winds uptick slightly with an incoming shortwave from the west. As a result, at least Increased Fire Danger Statements will be issued for western NC and northeast GA this afternoon and Thursday afternoon. Even if the criteria isn't fully met, low RH values, high heat stress, and very dry vegetation will enhance the risk for wildfire development. Expect this threat to linger into Friday and Saturday as well, so daily Fire Danger Statements remain possible through the rest of the week.

The Fire Danger Statement for all of western North Carolina was in coordination with the North Carolina Forest Service and is in effect from Noon to 8 PM today. A Fire Danger Statement is in effect from Noon to 8 PM today for northeast Georgia for ongoing dry fuels and RH values getting close to the critical threshold of 30%. A Fire Danger Statement will likely be needed for all of western NC and northeast Georgia again Thursday, as RH may dip a little lower and winds are expected to be gustier out of the SW. Can't rule out a potential Red Flag Warning on Thursday with critical thresholds for low RHs and gustier winds possibly being met.

Key message 2: Hot and dry through Saturday with high temperatures near daily records. A cold front may bring some rainfall to our area on Sunday, but any accumulations will likely be too small to improve drought conditions. Near-normal temperatures are expected early next week.

Upper ridging will build over the Southeast into Thursday while the Bermuda surface high keeps warm, SLY flow over our area. An embedded upper shortwave trof will move over the Carolinas early Friday, with heights rebounding quickly in its wake. A much broader and deeper upper trof will pass just to our north late Sunday into Monday and push a robust cold front through our area on Sunday. A weaker cold front does approach the western Carolinas late Thursday, however it gets pushed northward by the Bermuda high and washes out over the Appalachians on Friday. I wouldn't rule out a few showers over the NC mtns, mostly along the NC/TN Border region, late Thurs into early Fri, but any precip amounts would be minimal. The more robust front on Sunday has the potential to bring more widespread showers to our area, however the latest model guidance continues to produce little in the way of accumulations outside of the NC mtns and foothills, and accums over those areas are generally less than 0.15 inches. So it's still looking like any precip that we get from this system will have little impact on the current drought.

While temperatures will be summer-like and approach daily records through Saturday, the humidity will remain lower. Relative humidity values in the 25 to 35% range are expected each afternoon through the weekend, with values below 20% possible early next week. In addition, gusty winds are expected across our area on Thursday, Saturday, and Sunday which will likely increase the overall fire danger. Fortunately temperatures cool to near-normal behind the cold front on Monday and Tuesday, however the airmass remains very dry. In addition, freezing temperatures are possible over portions of the NC mtns early Monday and frost-producing temperatures are possible early Tuesday.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: VFR conditions will prevail through the 12Z TAF period with periods of thin cirrus. Light southwest winds through this morning will pick up in speed (6-12 kts) by early afternoon, with some low-end gusts possible during peak heating. Winds should subside after sunset and continue out of the southwest.

Outlook: VFR prevails the rest of the week and into the weekend. A few low VFR clouds, and perhaps stray SHRA, are possible late Thursday or Thursday night over the Appalachians.

CLIMATE

RECORDS FOR 04-15

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 89 1972 42 1943 64 1887 23 1907 KCLT 89 1936 46 1889 66 2006 28 1907 KGSP 91 2006 45 1913 69 1922 22 1907

RECORDS FOR 04-16

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 87 2006 42 1905 62 1945 26 1943 KCLT 89 2006 49 1890 64 1998 29 2008 1896 1991 1962 1945 KGSP 88 1888 54 1903 64 1945 24 1907

RECORDS FOR 04-17

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 89 1896 45 1890 63 1927 26 1904 KCLT 94 1896 47 1890 66 1896 30 2018 1949 KGSP 92 2006 51 1904 63 1927 25 1905

RECORDS FOR 04-18

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 90 1896 44 1921 60 1927 28 1905 1891 KCLT 93 1896 45 1983 66 1896 32 2001 KGSP 89 2002 51 1983 66 1927 28 1905 1967

GSP WATCHES/WARNINGS/ADVISORIES

GA...INCREASED FIRE DANGER from noon EDT today through this evening for GAZ010-017-018-026-028-029. NC...INCREASED FIRE DANGER from noon EDT today through this evening for NCZ033-035>037-048>053-056>059-062>065-068>072-082- 501>510. SC...None.