textproduct: Charleston

SYNOPSIS

A cold front will push offshore early Sunday. High pressure then builds into the area through mid-week, followed by another cold front on Thursday.

NEAR TERM /UNTIL 6 AM SUNDAY MORNING/

Tonight: A band of showers/tstms associated with an approaching cold front will steadily weaken/erode this evening as the corridor of strongest forcing with shortwave energy moves across the Great Lakes and the right entrance region of the polar jet passes by well to the north and northwest. The leading edge of precip moving into the Central Georgia should largely outrun the main frontal band over the next several hours and should largely dissipate prior to reaching the far interior zones by early evening. While a few showers could still occur across far interior areas, most areas will remain dry this evening. Rain chances are not expected to increase all that much overnight as the front moves from west-east across the local area during the early morning hours Sunday, which seems reasonable given the lack of significant forcing, meager deep-layer moisture and the absence of instability locally. Overnight pops around 20% will be common with fropa late, except 30-40% in the Allendale- Sylvanis-Metter corridor. Overnight lows will be closely tied to fropa, ranging from the lower-mid 50s in the Allendale-Metter corridor to the upper 50s/around 60 elsewhere.

Lake Winds: The latest NBM and HREF Grand Ensemble support gusts below 25 kt over the open lake waters this evening and overnight. Near zero probabilities for reaching Lake Wind Advisory criteria early evening only climb to 10-20% tonight as a cold front pushes through. Pre-frontal warm air advection will likely maintain unfavorable mixing given cold lake water temperatures in the mid- upper 50s. However, probabilities should ramp up around daybreak Sunday when the strongest cold air advection occurs. Given these anticipated trends, a Lake Wind Advisory is in effect from 6 AM to 7 PM Sunday.

SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/

Cold front continues to depart the region Sunday, allowing clear skies to gradually return. With the aid of deep-mixing and a strong low level jet, expect northwesterly winds to become a bit breezy in the wake of FROPA. Currently have gusts up to 30 MPH possible for much of the daylight hours. Dewpoints also look to plummet during this time with the influx of cooler air, which may resulted in some elevated fire concerns across our area - more on this in the Fire Section below. Otherwise, look for temperatures to be notably cooler than days past, as high only rise into the low to mid 60s.

Dry and seasonally cool temperatures prevail heading into the new week as sfc high pressure builds overhead. As such, have morning lows Monday and Tuesday near/just below freezing, with afternoon highs only rising into the 50s to lower 60s.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Upper level trough deepens across the Ohio River Valley mid- week before pushing eastward toward the Atlantic. Meanwhile, at the sfc, will see another cold front eject across the region late Wednesday night into Thursday, potentially bringing a few light showers to the area. Outside of this, should see dry conditions prevail for the remainder of the extended period.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions will prevail at CHS/JZI/SAV terminals through 00Z Monday. However, TEMPO MVFR conditions are possible due to lower stratus and/or vsbys associated with light showers along/near a passing cold front early morning Sunday, mainly in the 11-14Z timeframe. LLWS (WS015/24035KT) is also possible at CHS/JZI terminals overnight, mainly a few hours prior to cold fropa when southwest sfc winds remain below 10 kt (generally 08Z-11Z Sunday). Gusty west-northwest winds return at all terminals mid-late Sunday morning and afternoon, peaking in the 25-28 kt range until sunset.

Extended Aviation Outlook: Breezy northwesterly winds will prevail Sunday, with gusts up to 30 MPH possible through the afternoon. Otherwise, VFR conditions are expected.

MARINE

Tonight: Winds will increase overnight ahead of an approaching cold front. Guidance has trended slower with the ramp up to Small Craft Advisory conditions with the greater risk for frequent wind gusts around 25 kt Sunday morning, the exception being across the outer portions of the South Santee-Edisto Beach nearshore leg where 25 kt gusts likely start after midnight. A Small Craft Advisory begins for the South Santee-Edisto Beach leg at 2 AM Sunday. Seas will generally range between 2-4 ft, largest 15-20 miles away from the Charleston County Coast late night.

Sunday through Wednesday: Winds become breezy in the wake of FROPA, with direction shifting from westerly to northwesterly by Sunday afternoon. With the aid of deep-mixing and a strong low level jet, have gusts between 25-30 kts for much of the daylight hours. Thus, SCA will remain in place for all our waters. Should see winds weaken into Monday as sfc high pressure builds overhead, allowing all SCA to expire. Tranquil marine conditions are then expected through Wednesday.

FIRE WEATHER

Elevated fire danger will be possible Sunday afternoon in the wake of a departing cold front, as drier and cooler air infiltrates the region. This combined with antecedent dry fuels, breezy northwesterly gusts up to 30 MPH, and falling dewpoints could promote fire growth/development. Latest guidance suggest relative humidity values may be a limiting factor and remain just above Red Flag Criteria, so have opted to forgo any headlines for the time being. Will continue to monitor trends in the coming shifts. Nonetheless, we encourage folks to be cautious with any activity that could cause a spark, as fires can spread quickly under these conditions.

CLIMATE

The low temperature at KCHS so far today is 60. If the low stays above 60 prior to midnight, the record high minimum for the date (60/1974) will be tied.

January 10: KCHS: 79/2008 KSAV: 81/1972

Record High Minimum Temperatures: January 10: KCHS: 60/1974

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Lake Wind Advisory from 6 AM to 7 PM EST Sunday for SCZ045. MARINE...Small Craft Advisory from 9 AM to 8 PM EST Sunday for AMZ330. Small Craft Advisory from 2 AM Sunday to 7 AM EST Monday for AMZ350. Small Craft Advisory from 9 AM Sunday to 7 AM EST Monday for AMZ352-354-374.