Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
303 PM EDT Wednesday Jun 19 2013
Synopsis...
aloft - a closed low was on the coast from British Columbia to
Oregon...ridging reached across the middle Continental U.S. From south central
Canada to northeast Mexico...troughing stretched from Labrador to
the central Gulf Coast...and a ridge reached across Florida from the Gulf
to the Atlantic. At the surface - broad high pressure sprawled from
the Great Lakes to southwest Quebec...one frontal boundary stretched
from the middle-Mississippi Valley to the Middle-Atlantic States with a
second boundary that extended east from the Southern Plains and the
Gulf Coast states to off the eastern Seaboard then north to the
Canadian Maritimes...and high pressure over the open Atlantic
ridged west over Florida into the Gulf.
&&
Short term (tonight-friday)...
the middle-Continental U.S. Ridge moves east...reaching the middle-Mississippi and
central Gulf Coast by Friday...as the upper trough moves to the southeast U.S.
Thursday then settles south Friday to over and just east of Florida. The southern
most frontal boundary sags into northern Florida as it begins to decay
Thursday while the surface ridge slides east with a relaxing gradient
across the area. On Friday the boundary remains in place as it further
weakens while the Atlantic high pressure ridge starts to lift
north.
Isolated late night showers along with light southerly/southwesterly
winds could produce a couple of funnel clouds or waterspouts early
Thursday morning...similar to this morning.
The approaching trough and boundary adding slightly more moisture
and energy to the atmosphere...help maintain showers and storms
especially in the north. These will be isolated morning and
evenings but becoming scattered in the afternoons. The frontal
boundary sagging in with the ridge weakening as it shifts east
will transition the westerly flow of the past few days to more
southeasterly. The gradient will remain relaxed enough to allow
afternoon sea breezes but more limited each day. This will permit
the highest storm coverage and intensity to shift back toward the
coast and to the north. Temperatures will run near or just above
normal for the lows...highs will be above normal by a couple of
degrees.
Long term (friday night-next wednesday)...
upper level ridging over the plains and MS valley at the start of
the period will build east and bridge across a weak middle level and
inverted surface trough just offshore the southeast U.S. Coast
during the upcoming weekend as surface high pressure from the
western Atlantic builds west across the southeastern states and
North Florida. As the surface ridge builds in a developing east
to southeast flow will help to increase moisture across the entire
forecast area. The increasing moisture combined with an east to
southeast steering flow will keep the West Coast sea breeze close
to the West Coast where the highest probability of precipitation and greatest areal coverage
of showers and storms will reside each day...during the afternoon
and early evening hours...before the convection shifts west into
the adjacent Gulf waters each night.
Temperatures will run a few degrees above normal through the period
with overnight lows in the lower 70s inland areas...and middle to
upper 70s along the coast...with daytime highs in the lower to middle
90s...except slightly cooler readings along the immediate coast due
to the sea breeze.
&&
Aviation...
VFR conditions will prevail at the terminals through the period.
Scattered afternoon storms may cause brief tempo MVFR conditions
across inland and southern terminals through the rest of the
day...then early morning showers developing near the coast after
20/09z may again cause brief MVFR conditions to the coastal
terminals.
&&
Marine...
flow pattern transitions from westerly to southeasterly or easterly
but with relatively benign conditions. Winds and seas rather
light for the rest of the work week then increase some for the
weekend but stay at 15 knots/3 feet or less. The main hazard will
be isolated to scattered thunderstorms which may cause gusty winds
and locally rough seas.
&&
Fire weather...
the afternoon minimum relative humidity values will not reach
critical levels through the weekend.
&&
Preliminary point temps/pops...
tpa 78 91 76 91 / 20 50 20 50
fmy 75 92 75 92 / 20 50 20 50
gif 75 93 75 93 / 20 50 20 50
srq 77 90 74 91 / 20 30 20 40
bkv 71 92 70 92 / 20 50 20 50
spg 81 89 79 89 / 20 40 20 40
&&
Tbw watches/warnings/advisories...
Florida...none.
Gulf waters...none.
&&
$$
Synopsis/short term/marine/fire weather...09/rude
long term...57/McMichael
aviation...24/Colson
