Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
1037 am EDT Friday Mar 14 2014
high pressure will prevail through Saturday. A warm front will
lift into the area Saturday night before a complex low pressure
system moves in from the west Sunday through Monday night. High
pressure will then build over the area during middle and late week.
Near term /until 6 PM this evening/...
a zonal flow will persist aloft while at the surface a broad area
of high pressure pushes into the western Atlantic. This pattern
yields increasing warm advection in the low and middle levels with
sunny skies. Low-level dewpoints will rise through the day...
especially coastal sections where we could see some cumulus pop up
later in the day. Thickness forecasts from the latest ruc13 support
the existing high temperature forecast so we maintained temperatures in
the middle and upper 60s today.
Short term /6 PM this evening through Monday/...
tonight...the overall setup will remain largely unchanged. Southerly
flow will continue around the west side of the Atlantic surface high
and we will begin to see increasing clouds late in the evening and
overnight. Models are all in good agreement with some showers
developing in an area of convergence over the coastal waters
primarily after midnight. This activity looks as though it will
remain isolated and remain over the adjacent coastal waters where a
small sliver of slight chance probability of precipitation has been added to the forecast.
Otherwise...lows will be much warmer Thursday night. The forecast
features middle 40s inland ranging to upper 40s/low 50s at the coast.
Saturday...southerly flow along the western edge of high pressure
off the southeast coast will lead to a warm day well ahead of a
strengthening low pressure system over the Southern Plains. The
pattern will result in the warmest temperatures of the weekend with
1000-850 mb thickness values supporting afternoon highs in the
middle/upper 70s over most areas away from the immediate coast. Weather
conditions should remain dry until a warm front lifts north into the
area late Saturday night...with deepening moisture and isentropic
ascent. However...the bulk of precipitation is expected to remain west of
the forecast area near the vicinity of the deepening surface low. Have
therefore maintained only slight chance probability of precipitation for a majority of
Saturday night...then chances inland late. Overnight temperatures will
remain mild with warm air advection in place along with expanding
cloud cover. Expect low temperatures in the low/middle 50s away from the
Sunday through Monday...deep moisture will continue to advect over
the southeast ahead of a strengthening low pressure system tracking
from the south central United States to the southeast. Expect some
showers to break out by Sunday afternoon as enhanced forcing occurs
with a low level jet ahead of a strong 500 mb shortwave digging over the
deep south. Despite south/southeast flow ahead of the approaching
low...temperatures will be somewhat limited due to cloud cover over the
area. As a result...precipitation should remain in the form of showers
while temperatures peak into the upper 60s to around 70.
Precipitation coverage and intensity will likely ramp up Sunday evening and
persist through Monday morning as precipitable waters approach 1.75 inches while
enhanced forcing occurs with the strong 500 mb shortwave and h25 jet
aloft. Temperatures will also remain mild Sunday night...in the middle/upper
50s over most locations. Although most instability looks to remain
south and offshore...we can not rule out a few thunderstorms given
the amount of forcing that occurs as the system makes way to the
Atlantic. Have therefore introduced slight chances of thunderstorms
along with widespread showers Sunday night into early Monday. Expect
widespread showers to continue through much of Monday as moisture
lingers over the area while the middle/upper level low shifts offshore.
Temperatures will also cool off considerably throughout the day on Monday
as a northerly flow develops along the back edge of the departing
low pressure system. Monday highs could peak into the low/middle 60s
early...before cooling off into the middle/upper 50s over most
locations by Monday afternoon.
Long term /Monday night through Thursday/...
showers should be ongoing Monday night as a low pressure system
shifts offshore. Northerly flow along the back edge of the departing
system should result in cooler overnight lows...in the upper 30s to
lower 40s. Dryer conditions should then return over the region by
Tuesday evening and persist into Wednesday as high pressure wedges
southward over the area for a brief period. Temperatures will struggle to
warm significantly under The Wedge on Tuesday...but should gradually
warm to around 70 on Wednesday as The Wedge breaks down due to a
large trough of low pressure shifting over the Midwest. A weak/dry
cold front could shift through the area on Thursday...but high
pressure and near normal temperatures should prevail over the southeast
into late week.
Aviation /15z Friday through Tuesday/...
VFR conditions will prevail at kchs and ksav through 12z Saturday.
Extended aviation outlook...VFR ceilings/visibilities are expected at both
chs and sav terminals through Saturday. MVFR ceilings and/or visibilities are
likely Sunday and Monday with showers and low clouds associated as
a low pressure system shifts over the area. VFR conditions should
return at both terminals by Tuesday afternoon and persist into the
middle of next week.
today and tonight...tranquil conditions are expected across the
local waters under the influence of high pressure. Flow will be
northeast for a brief time this morning before quickly turning more
south and southeasterly as the center of the surface high shifts off
the East Coast. Winds will generally be around 10 kts or
less...except for up to 15 kts along the land/sea interface where
sea breeze will develop. Seas will be 1 to 2 feet. Overnight...the
flow will turn a bit more southwesterly and increase into the
10-15 knots range. Seas will tick upward to 2-3 feet.
Saturday through Wednesday...winds/seas should remain below Small
Craft Advisory levels through early Sunday as high pressure dominates
over the waters. Winds/seas should then increase/build Sunday
afternoon into Monday as a deepening low pressure system approaches
from the west and shifts off the southeast coast. We could see Small
Craft Advisory level conditions over outer Georgia waters and
northern SC waters Sunday night as a low level jet associated with
this system shifts offshore. 6 feet seas could linger over outer
Georgia waters into much of Monday as winds become northerly along
the back edge of the departing low pressure system. Conditions
should then improve by Tuesday as high pressure settles over the
waters through middle week.
relative humidity values are expected to fall to around 25 percent
for a few hours late this morning and into early afternoon away from
the immediate Georgia coast. Winds will increase in the afternoon
into the 15 miles per hour range out of the south and southeast. Dewpoints will
recover in the late afternoon and relative humidity values will rise
to above critical values. With this combination of low relative
humidities and elevated winds...a Fire Danger Statement will be
issued after coordination with surrounding offices.