textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

The aviation forecast was updated to reflect the recent 00z TAF issuance.

KEY MESSAGES

1. Warm, dry, and unperturbed weather will continue through Saturday. Fire weather will remain the biggest concern during this period, with a Fire Danger Statement in effect for western North Carolina and northeast Georgia. 2. Behind a cold front, significantly cooler temperatures are expected early next week. Some frost is possible over the mountains Sunday and Monday night, so precautions might be needed to protect sensitive plants. The air mass will also be dry, bringing a quick return to low RH and enhanced fire danger.

DISCUSSION

Key message 1: Warm, dry, and unperturbed weather will continue through Saturday. Fire weather will remain the biggest concern during this period, with a Fire Danger Statement in effect for western North Carolina and northeast Georgia.

All quiet across the western Carolinas today, with some very isolated cu developing over the Balsams and northeast Georgia, and mostly clear skies elsewhere. An elongated trough axis extending from the Ozark Plateau all the way into Michigan will provide the impetus for any active weather we receive over the next day and a half.

In all likelihood, that won't be much. A fairly dry air mass is in place currently, with 20+ degree dewpoint depressions observed at many ob sites before we have even reached peak mixing. Today's forecast profiles across most of the area look quite dry, with enough turbulent mixing at the top of the PBL to support mixing both lower dewpoints and higher wind gusts down to the surface. Consequently, much of the forecast area will see near-critical to critical RH this afternoon, paired with gusts up of 20 to 25 mph. With afternoon high temperatures climbing into the upper 80s across most of the area, it'll be another afternoon of hot and dry weather. In coordination with neighboring forecast offices and local land managers, a Fire Danger Statement will remain in effect through 8 PM this evening for all of western North Carolina and northeast Georgia. For the South Carolina Upstate, SCFC indicated fuels are sufficiently moist so as to preclude the need for a Fire Danger Statement. It seems likely that additional Fire Danger Statements will eventually be necessary for Friday and Saturday...which should both be similarly hot, dry, and breezy.

This evening, a loosely-organized band of showers associated with large-scale ascent ahead of the trough axis will push across the Tennessee Valley and make a run at the North Carolina mountains. Sadly for those who were hoping for a little drought relief, the morning HREF and REFS membership are in good agreement that this activity should fizzle out once it arrives in Appalachia. A couple showers over the mountains are within reason - maybe even a rumble of thunder - but generally think this should be low-impact. With even the high-end guidance barely eking out more than a few hundredths of an inch of QPF...it looks like this will do little to put a dent in ongoing drought conditions.

Key message 2: Behind a cold front, significantly cooler temperatures are expected early next week. Some frost is possible over the mountains Sunday and Monday night, so precautions might be needed to protect sensitive plants. The air mass will also be dry, bringing a quick return to low RH and enhanced fire danger.

Unfortunately, not much has changed from earlier thinking with regard to the passage of a cold front expected over the mountains late Saturday night and then east of the mountains Sunday morning. Guidance will show a robust band of showers and storms approaching from the west on Saturday afternoon, but we strongly suspect that it will reach the mountains Saturday evening and not get much farther than that, dashing our hopes for some relief from the ongoing drought. The models just don't show that much moisture return from the Gulf ahead of the approaching front. Areas along the TN border will be the lucky ones and should get enough rain to notice, but the front orientation and time of day are unfavorable east of the mtns. The new model blend QPF is most disappointing, with zero rain over the I-85 corridor and south/east of there. The drought will only get worse.

What the front will do is bring in a much cooler air mass that will drop temperatures back down to at or slightly below normal for mid-April, so it will almost feel like a change of seasons in reverse. That raises the possibility of some frost/freeze issues over the mountains for Sunday night and Monday night. The post-frontal period Sunday night could have some below freezing temps, but only at the very highest of elevations (above 6k feet). More likely will be low temps down into the middle 30s, even in the valleys, but there could be enough residual NW flow to keep the frost from forming. That won't be the case on Monday night, as the pressure gradient collapses and we have clear sky. Frost appears most likely to be widespread across the mountains and foothills by daybreak on Tuesday. Further developments in the forecast trend will determine whether or not people will have to take action to protect sensitive plants. The air mass should modify by Tuesday night, negating the frost threat. Temps will warm for the rest of the week.

Fire weather will probably also be a concern across the region early in the week, as afternoon relative humidity is likely to drop down below 25 percent again every day Monday through Thursday, though wind does not appear to be concerning at this time.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

At KCLT and elsewhere: VFR expected to continue thru the TAF period. Winds should go light within the first hour or so of the 00z TAFs. A broken line of convection is approaching the NC mountains at time of TAF issuance. The activity is expected to weaken quickly as it tries to cross the mountains this evening, but will leave the PROB30 at KAVL, as a SHRA may reach the terminal before dissipating. Otherwise, a period of thicker mid clouds will cross the area, with skies clearing out by daybreak Friday. Once winds die down, they will remain fairly light thru the period. They will shift to favor a NW direction overnight, then toggle back to SW across the Piedmont in the aftn (but remaining NW at KAVL).

Outlook: VFR prevails thru early next week. A cold front may bring brief rain chances Saturday night into Sunday, mainly along the NC mountains.

CLIMATE

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