Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Miami Florida
936 PM EDT Sat Jul 4 2015
currently, only high clouds left over from earlier convection
remains across the region. It would not appear that a repeat of
last night's convection is in order as there are no boundaries
offshore the southeast coast tonight and Atlantic activity has
also dissipated. However, some of the short term high resolution
models such as the hrrr continue to suggest it could happen so
will leave slight chance in the grids for now. Otherwise, looks to
be a tranquil weather night for South Florida.
Previous discussion... /issued 732 PM EDT Sat Jul 4 2015/
afternoon convection is rapidly diminishing across the area but
still in the southeast low level flow pattern. Thus, even though
the Atlantic is currently free of any activity the short range
high resolution continue to show a flare up around 04-06z and then
move onshore. This may or may not occur given the above flow so
kept out mention of thunderstorms and rain but did leave in place the vcsh for the
East Coast terminals. Southeast flow continues on Sunday so
afternoon convection should mostly be over the interior but more
southerly flow in the middle to upper levels could aid development
closer to kapf and kpbi.
Previous discussion... /issued 352 PM EDT Sat Jul 4 2015/
Saharan air layer is on the way...
* hazy skies overspread South Florida overnight-Tuesday
* less thunderstorms next few days, but pulse strong-severe possible
* focus of thunderstorms will be interior and Gulf Coast
high-res model consensus shows convection focusing over interior
South Florida this afternoon (occurring now) with dissipation by
early this evening...but with a few cells developing across the
East Coast metropolitan areas in the 10 PM-midnight time frame. Won't
get too cute with timing...so placed a slight chance of thunderstorms in
for the East Coast metropolitan this evening and for the overnight. Much
will depend on storm outflow interaction on whether it will be
completely dry for fourth fireworks displays this evening or if
there could be a few showers or thunderstorms to deal with.
An impressive Saharan air layer (sal) is approaching South Florida
from the southeast. Nassau sounding from this morning shows the
layer at around 7kft. This will be moving into South Florida
overnight and fully entrenched over South Florida sun-Tue...resulting in
very hazy skies as suspended dust particles from the Saharan
desert lie overhead. So added in haze for South Florida through
Tuesday. Fireworks will only add to the haziness across Southeast
Precipitable waters fall in the sal down to the 25th percentile
climatologically. This will lead to less convection into early
next week. However, characteristics of the sal are such that
strong or even pulse severe thunderstorms will be possible as very steep
middle level lapse rates (7c/km) overspread the area. So will need
to watch for the potential of isolated but intense thunderstorms
developing over the next few afternoon's...favoring the interior
and Gulf Coast.
By the middle to late week period (from previous discussion)...models
continue to show a TUTT-like low pushing to the west across the
Bahamas and into the Florida Straits. The trajectory of this
feature is now a bit further south than yesterday...as shown by
the GFS. The European model (ecmwf) is less bullish. This feature should have only
a minor impact on the weather for South Florida...only increasing
chances for showers and thunderstorms slightly as it passes by.
tranquil marine conditions will continue with the only threat
being gusty winds in and near isolated thunderstorms.
Preliminary point temps/pops...
West Palm Beach 78 90 79 91 / 20 30 20 30
Fort Lauderdale 80 90 81 91 / 20 10 20 20
Miami 80 91 80 91 / 20 10 20 20
Naples 76 92 76 92 / 20 40 50 30