Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
926 PM EDT Monday Jul 28 2014
a strong cold front will cross the region tonight and become
stationary south/southeast of the area through the middle
of the week. The front will then slowly move back towards the
southeast coast as a coastal trough late in the week through
early next week...bringing the possibility of some unsettled
Near term /until 6 am Tuesday morning/...
the Severe Thunderstorm Watch was allowed to expire at 9 PM.
As of mid-evening...the surface cold front was shifting into
northwest portions of the forecast area from the SC midlands and
central Savannah River area /csra/. A deepening middle and upper
level trough over the eastern U.S. Will push the cold front
through the remainder of the area and offshore during the early
Mainly isolated showers and thunderstorms will precede the cold
front...with any lingering convection pushing off the coast during
the overnight hours. Then...a much drier and cooler air mass will
overspread the area in wake of the front...as winds veer
northwesterly. Low temperatures will likely range from around 69
to 70 degrees far inland to the low to middle 70s along the coast.
Short term /6 am Tuesday morning through Thursday/...
Tuesday and Wednesday...the pattern will become much more quiet into
midweek as surface high pressure extends over the area behind a cold
front that becomes stationary well south of the region. Aloft...a
broad and highly anomalous trough of low pressure for middle Summer
will set up over much of the eastern Continental U.S.. this pattern will favor
cooler conditions than previous days...with afternoon high temperatures in
the upper 80s to around 90...warmest over southeast Georgia.
Overnight lows should range in the middle/upper 60s inland to low/middle
70s closer to the coast. High temperatures could be a degree or two cooler
Wednesday afternoon as a light onshore wind develops north of what
should eventually be a coastal trough developing off the southeast
coast. Although the setup should favor slightly more moisture return
over the region...a dry forecast will remain in place. However...a
shower and/or isolated thunderstorm can not be completely ruled out
along the coast where the best moisture convergence occurs along a
Thursday...the stationary front to our south will begin to lift
north throughout the day while transitioning into a coastal trough
off the southeast coast. A slight chance to chance of showers and
thunderstorms should return to the area by Thursday afternoon as
moisture deepens with precipitable waters approaching 1.5 to 1.75 inches in
response to this feature. Coverage should be greatest near the
afternoon seabreeze circulation along the southeast Georgia coast.
Given the likelihood of increasing cloud cover and light onshore
winds during peak heating...overall high temperatures should remain in the
upper 80s to around 90...warmest away from the coast in southeast
Long term /Thursday night through Monday/...
the baroclinic zone in the nearby Atlantic will have allowed for a
well pronounced coastal trough to set up near or just east of our
coastal waters late in the week. At the same time there are
indications that an unusually middle-summertime high pressure wedge
could attempt to set up shop inland. Upstairs the prominent and
persistent long wave trough in the east will amplify a bit
further...causing SW trajectories to advect moisture in off the Gulf
of Mexico. These factors will result in an increased chance of
showers/T-storms late in the week into early next week...which in
turn will keep maximum temperatures down several degrees below normal. At
present there are no indications of any sort of low developing on
the coastal trough...but there are hints that the tropical wave
currently in the eastern Atlantic may have developed into a tropical
cyclone by late in the forecast period...as it turns north of the
Caribbean islands and stays well out in the Atlantic with the
eastern trough still anchored in place.
Aviation /01z Tuesday through Saturday/...
the biggest immediate concern is the potential for direct impact
from thunderstorms. So far...coverage has been quite isolated and
based on what is currently upstream of the terminals...the
expectation is that neither will take a direct hit. Therefore...I
have kept thunderstorms in the vicinity for a few hours. Thereafter...skies will clear out
and winds will begin to veer around to become more westerly and
northwesterly with time.
Extended aviation outlook...VFR into Wednesday. Occasional flight
restrictions will be possible late in the week as a coastal trough
develops off the southeast coast Friday through Sunday.
tonight...the pressure gradient will remain fairly tight over some
of the marine zones ahead of an approaching cold front. This
gradient will support elevated southwest winds upwards of 15-20
knots...mainly in the outer Georgia waters...through the evening.
Seas will generally be 2 to 4 feet within 20 nm and 3 to 5 feet
beyond. The front will then shift through the marine zones by late
tonight...allowing winds to veer to the northwest and speed
Tuesday through Wednesday...winds/seas will remain well below Small
Craft Advisory levels through middle week...with winds eventually
veering around to an easterly flow and remaining at or below 10 to
12 knots. Seas will be no higher than 2 or 3 feet.
Thursday through Saturday...a coastal trough should develop over the
waters late Thursday or Friday and will persist close to the coastal
waters into the weekend. We will probably stay on the west side of
this surface feature...which suggests that winds will be some
easterly component at less than 15 knots through the forecast
period...while seas will be held at or below 3 feet. Scattered showers
and thunderstorms will have returned for late in the week due to
the proximity of the trough and the onshore fetch.
record high minimum temperatures for July 28th...
kchs...79 set in 1981.
Kcxm...83 set in 1999.
Ksav...81 set in 1878.