Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Miami Florida
929 am EDT Tuesday Oct 21 2014

Update...
showers and thunderstorms are expected to increase in coverage from
west to east as the day progresses. Based on current short term
model trends, it looks like a West Coast sea breeze will develop and
push across South Florida today, as the East Coast sea breeze
develops and remains over the East Coast metropolitan areas. This will
enhance shower and thunderstorm activity later this afternoon,
especially over the interior and East Coast metropolitan areas.
Therefore...the probability of precipitation have been raised over the eastern areas of
South Florida a little bit for this afternoon. A few of the storms
could even become strong this afternoon over the East Coast metropolitan
areas with gusty winds and heavy rainfall.

Thunderstorm activity is expected to decrease this evening as the
heating of the day diminishes. However, there will still be a chance
of showers through the overnight hours especially across southern
areas. Therefore, the forecast for isolated to scattered probability of precipitation will
remain over South Florida for tonight.

&&

Previous discussion... /issued 741 am EDT Tuesday Oct 21 2014/

Aviation...
showers will continue to affect the taf sites of South Florida
this morning before thunderstorms develop and affect the taf sites
this afternoon. The timing of the showers and thunderstorms is not
known at this time for the taf sites. So have only put in vcsh for
this morning and thunderstorms in the vicinity for this afternoon. However...once the
activity gets going over the area then a tempo group will be added
to the taf sites that will be affected by the showers and
thunderstorms.

The winds will be light and variable this morning before
increasing to around 5 knots this afternoon mainly from the
southerly direction over most of the taf sites. There could be a
East Coast sea breeze setting up this afternoon...but the sea
breeze should remain near the east coastal areas. So the only site
that will see a southeast wind flow will be kfll.

Kapf taf site should also see a West Coast sea breeze this
afternoon. So have made the wind direction at kapf a southwest
direction after 17z today.

The ceiling and visible will also remain in VFR conditions at this
time over all of South Florida taf sites. But could fall into MVFR
conditions if any shower or thunderstorm move through the taf
site. A tempo group would be added if this is expected or is
occurring at any of the taf sites.

Aviation...54/bnb

Previous discussion... /issued 450 am EDT Tuesday Oct 21 2014/

Discussion...

Showers and a few storms were located across the local waters and
Miami-Dade County. An area of low pressure across the Bay of
Campeche will move slowly eastward into the northwest Caribbean on
Thursday and then interact with the front through the end of the
week. Locally heavy rain is possible...especially Thursday night
into Friday.

An upper trough across the East Coast and southeast will
cutoff...with an upper low over the southern Great Lakes pushing
southeast across Virginia through Wednesday. At the surface...an
area of low pressure across the southern Great Lakes will push
southeastward and off the middle Atlantic coast this afternoon. This
will force a frontal boundary southward into the southeast
today...and towards the lake region by Wednesday evening.

West to southwest flow today will tap into the deep tropical
moisture over the Bay of Campeche...bringing considerable cloud
cover and numerous showers and a few storms. Isolated street
flooding is possible...mainly across the locations that received
heavy rainfall yesterday. Nocturnal showers will remain possible
across the regional waters...the Gulf Coast...and deep South
Florida.

The cold front will push southward into Florida through the day on
Wednesday...and the deep moisture may get shunted to the south.
The European model (ecmwf) is a little stronger than the GFS with the front...and
pushes the deep moisture back across deep South Florida and the
Keys. Due to the uncertainty...have lower probability of precipitation on Wednesday.

Models are in pretty good agreement that the disturbance
will begin to lift to the northeast late Thursday into Friday
across the Florida Straits as an upper trough digs into the
southeast states. The National Hurricane Center was monitoring
this area for development. Models have backed off somewhat
compared with previous runs...and have also trended further south.
However...there are still differences in how far south the deep
moisture gets pushed southward. A small deviation in the track of
the disturbance could lead to a heavy rainfall threat across
portions of the region Thursday night and Friday. So the forecast
remains highly uncertain through the end of the week.

Drier and slightly cooler air is forecast over the weekend as an
upper low digs south and southeast off the Carolina coast and a
cold front pushes through the region. However...some low level
moisture may get trapped below the inversion...leading to a few
showers late in the weekend or early next week.

Aviation...
some moisture is returning to South Florida. This will allow for
showers and thunderstorms to develop once again over the area.
Showers this morning will have a good potential to develop into
thunderstorms, mainly this afternoon. Have placed prob30 groups at
all sites to show this. Otherwise, mainly VFR conditions, with
possible brief periods of IFR due to heavy showers. Conditions
should improve after 00z.

Marine...
today through Wednesday regional winds forecast to be generally
around 10 knots with regional seas forecast to be generally around
2 feet. Shower and thunderstorm chances increase today through the
week...and locally higher winds and waves are possible in and
around storms. A broad area of low pressure across the Bay of
Campeche is being monitored by the National Hurricane Center.
There was a 50 percent chance of development into a tropical
cyclone over the next 5 days. The disturbance is forecast to move
east into the northwest Caribbean and interact with a front
Thursday and Friday.

&&

Preliminary point temps/pops...
West Palm Beach 83 71 84 72 / 70 30 40 20
Fort Lauderdale 83 74 83 75 / 70 30 40 30
Miami 83 72 84 74 / 70 30 50 20
Naples 82 71 84 70 / 60 30 40 20

&&

Mfl watches/warnings/advisories...
Florida...none.
Am...none.
GM...none.
&&

$$

Short term...55/cwc
long term....55/cwc

National Weather Service Glossary of Abbreviations