textproduct: Columbia

WHAT HAS CHANGED

A Fire Weather Watch has been issued for Saturday as confidence continues to increase for potential critical fire weather conditions. A Lake Wind Advisory is now in effect tonight into Saturday as strong winds move in behind the front. 06z Aviation updates.

KEY MESSAGES

- 1. Near record temperatures expected this afternoon before a cold front moves through tonight with a slight chance for a couple showers.

- 2. Fire weather concerns are expected this weekend, especially Saturday with a Fire Weather Watch now issued.

DISCUSSION

KEY MESSAGE 1: Near record temperatures expected this afternoon before a cold front moves through tonight with a slight chance for a couple showers.

The forecast remains largely on track for today as the strong upper ridge, warming 850 mb temperatures near the NAEFS 99th percentile, and strengthening southwesterly flow brings near record temperatures. Temperatures are expected to top out in the upper 80s with a couple spots reaching 90 possible. The record at both CAE/AGS is 88F and both of these records may be in jeopardy this afternoon with the latest forecast for both sites at 89F. The latest NBM even has its 25th percentile max temperature this afternoon tying the record. After these near record temperatures, the well advertised cold front approaches during the late evening hours. PWAT's should reach 1.20-1.40" ahead of this front and the 00z HREF indicates a couple showers or even a weak storm could be possible tonight, mainly toward the Pee Dee, but majority of the area should remain on the dry side. The main story with this front will be the strong CAA that ensues behind it, bringing much cooler and drier air to the region. This along with a tightening pressure gradient should yield wind gusts of 25-30 mph with the frontal passage and behind it, continuing into Saturday. Isolated gusts to 35 mph seem reasonable considering recent RRFS/HRRR output. Due to this, a Lake Wind Advisory is now in effect from Midnight tonight, until 2 PM Saturday.

Breezy northeasterly winds continue much of Saturday as a tight surface pressure gradient remains in place with robust Canadian surface high pressure nearing the region from the northwest. This feature near the NAEFS climatological max will aid in ushering in a much cooler/drier air mass with temperatures this weekend remaining near to just below normal. After this, ensemble guidance is in good agreement that the surface high should offshore into the early week with upper ridging building overhead. This should bring continued mostly dry weather and temperatures that rise back above normal through the early to mid week.

KEY MESSAGE 2: Fire weather concerns are expected this weekend, especially Saturday with a Fire Weather Watch now issued.

Confidence has continued to increase in hazardous fire weather conditions Saturday behind the cold front. There is strong agreement that robust CAA and a tightening surface pressure gradient behind the front should aid in bringing northeasterly winds that gust up to 25-35 mph starting late tonight, continuing much of the day Saturday before diminishing during the late afternoon hours. While there may be a bit of a lag in crashing dew points behind the front, dewpoints should quickly approach the 20s during the morning hours Saturday, bottoming out in the low 20s to upper teens during the afternoon. This is expected to yield RH values that fall below critical values by the late morning to early afternoon with strong northeasterly winds continuing. The strongest surge of CAA and winds appears to come overnight into Saturday morning, thus not bringing ideal overlap with the lowest RH values, but there could still be a couple hour window during the late morning to early afternoon with conditions nearing Red Flag criteria. Even outside of this window, RH values that could fall into the upper teens, with lingering wind gusts will bring conditions favorable for rapid fire spread should one start. Additionally, The latest REFS shows much of the FA with probabilities for RH less than 25% and wind gusts above 25 mph nearing 60-80%.

Due to these meteorological factors combining with very dry fuels from persistent drought conditions across much of the region, a Fire Weather Watch is now in effect starting 8 AM Saturday, continuing into the evening hours. Extreme caution will need to be taken with any activity that could spark a fire as the threat will for rapid fire spread will be high, especially late Saturday morning through the afternoon.

Moisture is still expected to recover some on Sunday with much weaker winds now out of the east to southeast, but RH values mainly along and north of I-20 could still fall under 30% so elevated concerns will still exist.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

VFR conditions expected.

A good amount of low-level mixing due to strong low-level jet overnight will keep skies clear and visibilities p6sm. Wind is mostly out of the south to southwest through sunrise, with sustained winds between 5-10 knots. Radar indicates 35-40 knots of wind between 1-2kft, and have gone ahead and mentioned llws beginning around 1.5 kft for winds out of the south around 40 knots at all sites. This shear should continue through 14-15z when better mixing will begin to bring up surface winds and increase the wind gusts through the daytime hours ahead of an approaching cold front. Winds will remain strong and gusty with gusts between 20-25 knots out of the southwest through much of the day, then as the front moves through between 02z-06z winds turning more northwesterly. As for any restrictions through the entire period, with good mixing and a drier low-levels due to this mixing, visibilities will remain p6sm and skies mostly clear through early evening. Some mid/upper level vfr cloudiness is expected after 00z at all sites as the front pushes through the region.

EXTENDED AVIATION OUTLOOK...A cold front moves east of the area Friday night with winds shifting to the North then Northeast on Saturday. This will usher in another reinforcing cool and dry air mass for the weekend. Some gusty winds are possible Saturday behind the front. Vfr conditions expected into the middle of next week.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Lake Wind Advisory from midnight tonight to 2 PM EDT Saturday for SCZ016-018-020>022-025>031-035-037-038-041-115-116- 135>137. Fire Weather Watch from Saturday morning through Saturday evening for SCZ016-018-020>022-025>031-035-037-038-041- 115-116-135>137. GA...Lake Wind Advisory from midnight tonight to 2 PM EDT Saturday for GAZ040-063>065-077. Fire Weather Watch from Saturday morning through Saturday evening for GAZ040-063>065-077.