Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Melbourne Florida
435 am EDT Wednesday Jul 30 2014
Today...an unusual July weather pattern will bring a frontal
trough into central Florida and some drier air into our northern
sections...especially Lake County. Deeper moisture across the
south (okeechobee to the Treasure coast) will support scattered
storms this afternoon with much reduced storm chances north of
Orlando. But there is some question how far south this lower
dewpoint air will get as GFS MOS is pulling back a bit. Given the
strong surface heating that will occur and the development of an East
Coast sea breeze...have introduced a less than 20 pop for showers
over Volusia County based on mesoscale models (local WRF and hrrr)
even though the GFS does not indicate any rain there.
Rain chances will increase to the south where low levels will
remain quite moist but drier air in the middle levels. This will
promote a few storms with strong wind gusts south of Orlando. Maximum
temperatures in the lower to middle 90s.
Tonight...axis of high precipitation water will remain over southern
sections and GFS shows weak low pressure developing which could
enhance low level convergence. So will hold onto at least a slight
chance of storms south of the cape.
the current anomalous weather pattern will break up through the end of the
week. A 100kt h30-h20 jet streak over the Midwest will round the
base of deep layer trough over the eastern Continental U.S....feeding into a second jet
streak over the Canadian Maritimes. As the combined jet energy
transitions downstream...the troffing pattern over the eastern Continental U.S. Will
dampen out...which in turn will allow the Atlantic ridge axis to rebuild
over the Florida Peninsula.
With the ridge axis returning as the dominant weather feature for central
Florida...diurnal convection distribution will be determined by the mean
h100-h70 flow. Remnant low level trough over the Gomex on Thursday will keep
the ridge axis from building much further north than the Florida Straits...
resulting in a weak S/SW flow below 10kts. While a southwesterly flow would
favor the east Florida coast for convection...such a weak environmental flow
will make it quite difficult for the east/West Coast sea breezes to
make much inland progress. Furthermore...lingering dry air and
subsidence aloft will limit total coverage to the 20-30pct range.
By Friday...whatever remains of the frontal trough will be squeezed out
of play by the Atlantic ridge building northwest and a deep layer ridge over the
Gomex/Southern Plains. Deep srly flow will prevail that will allow both
east/West Coast sea breezes to make nearly equal inland progress.
Moisture will return as well...allowing storm coverage to return to
a more seasonable 40-50pct.
S/southwesterly flow through the end of the work week will generate above average
temperatures with afternoon maxes in the l/m90s...mins in the M/u70s.
pattern looks about par for central Florida into early next week as the
Atlantic ridge axis remains the dominant weather feature. Both GFS/European model (ecmwf)
models maintain a short wave trough over the eastern Continental U.S....but a deep
layer cyclone over the Pacific northwest will intercept much of the northern stream
jet energy through the weekend. This will prevent the trough from gaining
the strength necessary to suppress the ridge axis much further south
than the central Florida Peninsula. By Monday...models hint that a weak Erly
wave over the tropics will have worked far enough west to impact the
local weather...even if indirectly. Scattered afternoon/evening thunderstorms and rain showers will be the rule
with temperatures near average.
patchy fog and low clouds may produce some MVFR ceilings/visibilities through
13z as frontal trough settles south into the area. Best chance for
storms this afternoon will be southern terminals (vrb-sua) as shown by
thunderstorms in the vicinity which may get upgraded to tempo groups for one or more sites.
More isolated coverage expected to the north (mco/dab/sfb/lee) as
some drier air filters in.
today...frontal trough sagging into the northern (volusia) waters
early this morning will settle across central Florida through tonight.
This will result in a weaker offshore flow and allow an onshore
(e-se) flow to develop this afternoon near the coast. Scattered storms
are expected to develop near the Treasure Coast and push offshore
with lower coverage to the north.
Thu-sun...anomalous troffing pattern over the eastern Continental U.S. Will weaken
through late week...allowing the Atlantic ridge axis to rebuild over western
Atlantic/eastern Gomex. A light to gentle S/southeast breeze will prevail on Thursday...
becoming gentle to moderate Friday and continuing through weekend as the ridge axis
entrenches itself over the region. Seas at or below 2ft nearshore and 2-3ft
offshore through Sat. Seas becoming 2-3ft nearshore and 3-4ft offshore on
sun as a long Erly fetch around the base of the Atlantic ridge pushes a
small swell into the east Florida coast.
Preliminary point temps/pops...
dab 91 74 91 77 / 20 10 30 20
mco 94 74 95 77 / 20 10 20 10
mlb 90 75 91 78 / 30 20 30 20
vrb 90 73 90 77 / 50 30 30 20
Lee 94 75 95 75 / 10 10 20 10
sfb 94 75 95 77 / 20 10 20 10
orl 94 76 95 77 / 20 10 20 10
fpr 90 73 90 77 / 50 30 30 20