Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 301942
Area Forecast Discussion
National Weather Service Charleston SC
342 PM EDT SAT JUL 30 2016
Atlantic high pressure along with an inland trough will prevail into
early next week. High pressure will then become suppressed further
to the south which could allow a weak cold front to approach from
the north by the middle part of next week.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Not much pattern change tonight with high pressure centered over
the Atlantic extending west across the area and a trough east of
the Appalachians. Some weak shortwave energy will likely move by
to the north and northwest and this could keep a few showers/weak
thunderstorms around, especially through the evening. Lows mainly
in the mid to upper 70s inland and closer to 80 at the coast.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Sunday and Sunday night: Aloft, the ridge axis will stretch from
southern GA through the Gulf coast while a weak trough will
stretch across the Great Lakes and OH Valley. No significant
shortwaves are forecasted to impact the area. At the surface, we
will be under the western periphery of the subtropical high centered
to our east while the inland trough remains just to our northwest.
Models indicate better convective coverage. Instability across the
board will be better than the past few days and PWATs should exceed
2 inches. Even the model soundings look more conducive to convection
compared to the past few days. The best coverage should be across
the Charleston Tri-County area, closer to the inland trough. But
chance POPs at minimum are expected everywhere, with initiation
probably starting with the sea breeze in the afternoon and then
quickly developing inland. Pulse type storms are expected. The sea
breeze and cold pool boundary interactions should help
initiate/backbuild storms. Weak low and mid level winds will prevent
the storms from moving too much. The strongest storms could produce
heavy rainfall and maybe localized flooding if they stay in the same
area (or backbuild) for too long. The overall severe threat is low,
but decent DCAPEs indicate a wind potential from the strongest
storms. Convection over land should trend downward into the evening
and overnight hours. But it could linger the longest over the
Charleston Tri-county area before new convection tries to develop
over the coastal waters.
Temperatures are expected to be a few degrees lower than the past
few days, closer to normal.
Monday through Tuesday: The upper ridge will break down and become
more centered between the desert southwest and the lower Mississippi
Valley. Moisture will increase across the area, with precipitable
water values around 2.25 inches, and 500 mb temperatures will cool
further to around -8 C. This will all happen as a well defined
shortwave approaches the area from the northwest Monday afternoon
and evening. As such, it appears Monday will likely be the most
active day and the increase in convective coverage will extend
through Tuesday. The near storm environment still isn`t overly
impressive for severe thunderstorms, but there will likely be a few
strong to marginally severe storms where boundary interactions
occur. As the calendar shifts over the August, temperatures will
cool more into the low to mid 90s.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
No significant changes were made to the going forecast for the long
term period. A return to more active showers and thunderstorms will
continue at least for Wednesday and Thursday as embedded shortwaves
approach and push through the area from the northwest. The forecast
generally features 30-40 percent chances each afternoon and evening,
and these values will certainly be refined as the time period draws
closer. Temperatures also continue to look cooler, with highs mainly
in the low 90s, which would be right around normal for early August.
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Low risk of showers/thunderstorms at KCHS/KSAV, mainly from about
18-23Z today. Otherwise, VFR will prevail through 18Z Sun.
Extended Aviation Outlook: Brief flight restrictions are possible
with afternoon/evening showers/thunderstorms. Otherwise, VFR will
Tonight: Atlantic high pressure will prevail along with an inland
trough. This pattern will favor south to southwest winds that will
gust near Advisory levels /25 knots/ at times, due to nocturnal
surging. Seas mostly 3 feet or less within 20 nm and up to 4 feet
beyond 20 nm.
Sunday through Thursday: The persistent pattern of an inland trough
and high pressure to the east will generate south to southwest winds
across our waters. The periods of strongest winds will likely occur
in the afternoon and evening hours along the land/sea interface with
the development of the sea breeze circulation. Winds will generally
top out around 20 kt Sunday night, then 15 kt the rest of the week.
Seas will average 1-3 ft with the potential for some 4 footers
during the time periods with the strongest winds.
Record high minimums for 30 July...
KCHS: 80 set in 2011.
KCXM: 82 set in 1999 and previous.
KSAV: 81 set in 1878. /will not be broken/
Record high maximums for 30 July...
KCHS: 100 set in 1999.
KCXM: 98 set in 1942 and previous.
KSAV: 101 set in 1896.
Record high minimums for 31 July...
KCHS: 79 set in 1999.
KCXM: 84 set in 1999.
KSAV: 80 set in 2010.
***Top 5 Warmest Months on Record by Average Temperature***
Charleston International Airport - KCHS (Records Back to 1938)
1. 86.1 - July 1986
2. 86.0 - July 2016 (2 days left)
3. 85.5 - July 1993
4. 83.9 - July 1992
5. 83.8 - July 1998
Savannah International Airport - KSAV (Records Back to 1874)
1. 86.7 - July 1993
2. 86.0 - July 2016 (2 days left)
3. 85.7 - July 1986
4. 85.7 - July 1875
5. 84.8 - August 2011
Downtown Charleston - KCXM (Records Back to 1893)
1. 86.0 - July 1998
2. 85.5 - June 1998
3. 84.9 - July 1977
4. 84.8 - July 1986
5. 84.8 - July 2016 (2 days left)
***Top 5 Driest Months on Record for July***
Savannah International Airport - KSAV (Records back to 1871)
1. 0.82 - 1888
2. 1.21 - 2016 (2 days left)
3. 1.25 - 1881
4. 1.33 - 1949
5. 1.35 - 1972