Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Miami Florida
420 am EST sun Dec 21 2014
A few areas of low pressure will ride along a weak warm front
today, across central and northern Florida. South of this
boundary, moisture was slowly increasing, and this trend will
continue on east-southeast to southeast surface winds today. Aloft, southwest flow will
increases cloudiness this afternoon as a slightly stronger
disturbance delivers showers across the Gulf waters tonight. Most
of this precipitation should stay north and west, but a few showers
can't be ruled out tonight for the West Coast and the lake region
as this wave passes near Tampa.
Into next week, a trough deepens through the Midwest, and surface
winds will veer to the S and SW Monday and Tuesday in response.
This moist humid flow could produce a few showers on both days,
with temperatures maximum temperatures warming a few degrees each day.
Guidance has continued to delay arrival of this week's cold front
and associated showers and thunderstorms. With the upper ridge
through the Caribbean remaining strong, the entire pattern is even
more amplified. In response, probability of precipitation were delayed by the blended
guidance, but are slow to make up for model biases/trends. Both
the European model (ecmwf) and the GFS, along with many ensemble members, have less
than 0.5" of quantitative precipitation forecast along the East Coast for the period beginning 18z
Wednesday ending 0z Thursday. In addition, quantitative precipitation forecast may struggle to reach
even the interior by midday Wednesday. It appears as though
subsidence associated with the Caribbean upper ridge will supply a
slice of drier air aloft which may take much of Wednesday to
dislodge. In addition, total quantitative precipitation forecast has been reduced for the eastern
half of the County Warning Area for the entire event. A later frontal passage
could mean a better chance for some stronger storms, although
model soundings don't look more impressive than last night's runs.
With the entire upper air pattern shifted north, and considering
the track of the high pressure behind the delayed front,
temperatures have warmed with Christmas day not looking quite as
chilly as it did several runs ago. With West Coast ridging
breaking down, the pattern isn't as favorable as it could be for
cold air delivery. Nonetheless, a much drier airmass with
dewpoints falling into the lower 50s and upper 40s Thursday
afternoon, combined with high pressure overhead, will still give
the region a chilly Friday morning.
High pressure covers much of the southeast into next weekend, with
easterly flow returning and moisture increasing, leading to
more clouds and showers along the East Coast, at the end of the
East to southeast flow continues today. A cold front will
approach the Gulf waters Wednesday with numerous showers and
thunderstorms, then into the Atlantic waters late Wednesday into
early Christmas day. Winds will veer to the south and southwest by
midweek, then northwest and north into Christmas. Expect building
seas, especially through the offshore Gulf waters Wednesday night,
and the Gulf Stream waters on Thursday. High pressure and
easterly flow return to end next week.
Preliminary point temps/pops...
West Palm Beach 79 69 81 71 / 10 20 20 10
Fort Lauderdale 79 71 81 72 / 10 10 20 10
Miami 80 70 81 71 / 10 10 20 10
Naples 79 66 78 67 / 10 30 20 10