textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Low confidence on rain chances from potential cold front late Sunday.

Updated the aviation discussion for the 18z TAFs.

KEY MESSAGES

1. One more day of low RH before a little relief is in store for Monday. Anomalously-warm temperatures continue. 2. Dry and hot into early next weekend. Daily record highs could be in jeopardy Tuesday through Saturday. A cold front may finally bring some drought relief Sunday, but that is more uncertain.

DISCUSSION

Key message 1: One more day of low RH before a little relief is in store for Monday. Anomalously-warm temperatures continue.

No major changes to the forecast thinking for the weekend. High pressure presently centered over Cape Cod will continue ridging down the Mid-Atlantic coast this afternoon. A weak remnant frontal boundary will lift north again as the high retreats northeastward going into this evening, supporting a return to SSW winds by mid-afternoon (actually already underway...with many sites over the I-77 corridor starting to curl around to the SE already). Expect this trend to continue through the afternoon and for a steady SW breeze to develop everywhere in the next few hours.

Despite this, moisture should remain scant the next two days...with dewpoints in the mid-40s across much of the area this afternoon...with a slow rebound into the lower 50s by Monday afternoon. The result should be one more day of near-critical to critical RH across the Piedmont and Upstate. For North and South Carolina, today's winds are expected to remain too light to justify a Fire Danger Statement despite the low RH...while in northeast Georgia, whose forestry officials only require that the wind or RH criteria be met to justify a FDS, a Fire Danger Statement remains in effect until 8 PM this evening. RH should rebound modestly on Monday in response to slowly-increasing moisture from the south, but RH is still likely to fall to 30-35% during peak heating.

Key message 2: Dry and hot into early next weekend. Daily record highs could be in jeopardy Tuesday through Saturday. A cold front may finally bring some drought relief Sunday, but that is more uncertain.

A broad upper ridge will be in place through mid-week before a weak shortwave trough crosses the area Thursday. A sharper ridge returns Friday and Saturday before a stronger shortwave moves in late Sunday. A Bermuda surface high will be in place through much of the week bringing summer-like heat to the area. The main difference to a usual Bermuda high will be the lack of humidity with an east-west oriented surface ridge over the area keeping the low level flow more westerly with no significant Gulf moisture inflow. This allows the heat to build with highs in the 90 degree range outside of the mountains Wednesday through Saturday. With the lack of moisture, relative humidity values will remain in the 25 percent range those days as well. No significant rainfall chances either as a Thursday cold front is blocked even as the weak shortwave moves through. All this will help worsen drought conditions. That may finally change on Sunday with the stronger shortwave potentially pushing a cold front into the area late in the day. That said, forecasts for cold fronts on day 7 have a history of being delayed, so let's hope for some relief but don't get too excited just yet.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

At KCLT and elsewhere: VFR to continue for the 18z TAF period. Winds are predominantly SSW at most sites by this hour, and should remain that way through the period. Fairly light 5-10kt winds expected this afternoon, dying down somewhat but remaining steady overnight...then picking back up somewhat faster...with gusts up to ~18kts Monday afternoon. Mostly FEW cirrus this afternoon and evening will begin to thicken overnight, becoming SCT by daybreak, and eventually becoming BKN by Monday afternoon.

Outlook: Expect dry, VFR conditions to persist thru the middle of this week.

CLIMATE

RECORDS FOR 04-14

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 86 2006 36 1907 62 1922 24 1950 KCLT 89 1941 46 1907 69 1922 27 1950 KGSP 92 1916 48 1901 67 1922 22 1907

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 until 8 PM EDT this evening for GAZ010- 017-018-026-028-029. NC...None. SC...None.