textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated aviation discussion.

KEY MESSAGES

1. Very warm conditions, with very low-to-critical relative humidity is forecast each afternoon through Friday, keeping the fire danger elevated. Any fire that develops has the potential to spread quickly. No outdoor burning! 2. Trending towards a wetter pattern this weekend into early next week. However, drier conditions may return briefly Sunday into Monday behind the first cold front and ahead of the second cold front (which is expected on Tuesday). Temperatures remain above normal through the period, with the exception of Monday.

DISCUSSION

Key message 1: Very warm conditions, with very low-to-critical relative humidity is forecast each afternoon through Friday, keeping the fire danger elevated. Any fire that develops has the potential to spread quickly. No outdoor burning!

An upper ridge extending from the mid-Miss Valley into the Great Lakes early this morning will continue to build into the eastern states today, before breaking down tonight into Friday as two upper lows: one centered over the Canadian Prairie and the other over the Canadian Maritimes deepen and broaden. Anomalously high heights along with SW low level flow will support very warm conditions through Friday, with max temps forecast to be around 10 degrees above climo both days. Despite the SW flow, low level trajectories are originating off the eastern Gulf, where precipitable water values are well below normal. Thus, moisture flux into our CWA will remain meager, and dewpoints will continue to only creep upward as the air mass continues to modify. Another afternoon of critical RH is therefore expected today, with widespread 20-25% values, and at least spotty values in the teens. Winds will be less of a factor than yesterday, but warmer temperatures, the low RH, and very dry vegetation will result in yet another day with abnormally high (for mid-spring) fire danger. Fire Danger Statements for today will be limited to northeast GA...where only one critical meteorological parameter is necessary for an FDS...and will allow the ongoing burn bans for the Carolinas to speak for themselves. Similar temps and slightly higher RH is expected Friday afternoon...but we still anticipate widespread 25-35% values during peak heating...which will be enough to again elevate the fire danger in light of the dire fuels situation and slightly stronger winds.

Key message 2: Trending towards a wetter pattern this weekend into early next week. However, drier conditions may return briefly Sunday into Monday behind the first cold front and ahead of the second cold front (which is expected on Tuesday). Temperatures remain above normal through the period, with the exception of Monday.

We finally see a pattern change this weekend into early next week as rain chances return ahead of two cold fronts. The first front is expected on Saturday and the second one is expected on Tuesday. Rainfall amounts continue to look better with the second front on Tuesday compared to the first front on Saturday. Removed PoPs again Friday night as the NBM continues to be too fast regarding rain chances compared to global and high-res guidance, which has rain generally holding off until closer to daybreak Saturday. The NBM has been fairly consistent in showing 0.50" of rainfall or less across most of the GSP CWA on Saturday as well as depicting the highest rainfall amounts across the mountains with lower rainfall amounts elsewhere. The NBM shows 0.25" to 0.5" of rainfall across the mountains, with locally higher amounts from 0.6" to 0.75" along the southern NC/TN border counties. East of the mountains the NBM only shows 0.15" to 0.25" of rainfall. The NBM seems to be in fairly good agreement with the 12Z LREF as LREF probabilities show a 30% to 50% chance of exceeding 0.5" of rainfall over Graham, Swain, and Macon counties with less than a 25% chance of exceeding 0.5" of rainfall elsewhere. As for rainfall amounts on Tuesday, LREF probabilities have trended down compared to this time yesterday, with only a 30% to 50% chance of exceeding 0.50" of rainfall along the NC/TN border counties, northeast Georgia, and the far northwestern South Carolina Upstate (mainly Pickens and Oconee counties) and less than a 25% chance of exceeding 0.50" of rainfall elsewhere. However, the NBM is showing slightly higher probabilities of exceeding 0.50" of rainfall on Tuesday. Will continue to monitor rainfall trends regarding Tuesday closely in the coming days.

The 18Z Euro and 12Z Canadian show dry conditions returning Sunday into Monday behind the first cold front while the 00Z GFS keeps rain chances around behind the front. How far south the surface high builds into the region behind the departing front will determine if dry conditions return or not behind the front. The 00Z GFS and 12Z Canadian show rain chances lingering behind the second front on Wednesday as they are faster with the next system approaching the area. Meanwhile, the 12Z Euro shows dry conditions returning behind the front on Wednesday as it is much slower with the next approaching system. Thus, confidence on dry conditions returning Sunday into Monday and again on Wednesday remains low due to model disagreement.

Temperatures remain above normal this weekend into early next week with the exception of Monday when highs fall near to below normal.

AVIATION /12Z THURSDAY THROUGH MONDAY/

At KCLT and elsewhere: With a dry air mass remaining in place... VFR/SKC conditions are forecast through this TAF period. The caveat is that brief periods of 3-6SM visby can't be ruled out due to HZ or smoke originating from wildfires over south GA/northern FL, but timing of this...or even if it will occur at all...is highly uncertain. Otherwise, mostly light/vrbl winds or light SW winds are expected early...becoming SW at 6-8 kts this afternoon, before becoming light again this evening.

Outlook: Dry, VFR conditions are expected to persist thru Friday as broad surface high pressure lingers over the region. A frontal system will likely bring showers and some associated restrictions this weekend.

GSP WATCHES/WARNINGS/ADVISORIES

GA...INCREASED FIRE DANGER from noon EDT today through this evening for GAZ010-017-018-026-028-029. NC...None. SC...None.