Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Miami Florida
130 am EDT Tuesday Jul 22 2014
the winds will be light and variable through 10z before becoming
south to southeast around 5 knots at all of the taf sites. The
winds will then increase to 5 to 10 knots by late this morning
into this afternoon along the East Coast taf sites...while at kapf
taf site the winds will swing to a westerly direction at 5 to 10
The weather will remain dry over all of the taf sites through 10z
this morning before some showers will develop and push into the
taf sties. Once the sea breezes develop late this morning and
pushes inland there will be a chance for thunderstorms. So will
keep the thunderstorms in the vicinity in the forecast from 15/16z through the afternoon
hours at all of South Florida taf sites.
The timing of the showers and thunderstorms to affect the taf
sites are unknown. So will keep the ceiling and visible in the VFR
conditions on this taf site package...but will continue to monitor
the weather to see if tempo's will be needed for reduce visible and
ceiling conditions over the taf sites.
Previous discussion... /issued 905 PM EDT Monday Jul 21 2014/
The 00z sounding indicates that tropical moisture continues
across the region with the precipitable water just shy of 2.3 inches. Recent
radar returns indicate that convection has subsided across the
Atlantic waters and just lingering light showers across the
western peninsula with showers/thunderstorms noted across the
near shore Gulf waters.
The short term forecast was updated for this evening and
overnight. Although convection has subsided across the Atlantic
waters this evening...a tropical wave continues to track westward
south of Cuba and the northern periphery of the wave could still
provide potential for additional showers/thunderstorms across the
Atlantic waters and the East Coast metropolitan areas with a chance of
showers and thunderstorms in the forecast during the over night
hours for these areas. Additional convection is also possible
across the Gulf waters as well.
Previous discussion... /issued 732 PM EDT Monday Jul 21 2014/
showers and storms are winding down early this evening. Guidance
is indicating that showers or possibly storms may redevelop over
the Atlantic waters and move towards the East Coast taf sites
overnight. For now...added vcsh after 06z. If showers and storms
develop overnight...it could disrupt the normal diurnal
cycle...with not much activity near the East Coast during the
afternoon. Kept thunderstorms in the vicinity after 14z due to the uncertainty...but tempo
groups will most likely need to be added for many of the taf sites
on Tuesday. Light winds are forecast overnight...with light
southeasterly winds during the day on Tuesday.
Previous discussion... /issued 246 PM EDT Monday Jul 21 2014/
a trough to the north of the area has brought increased moisture
and instability to South Florida today. This has allowed
widespread showers and thunderstorms across the Atlantic waters
and Atlantic coastal areas. The low is prognosticated to dig to the
southwest and deepen somewhat through the afternoon and evening.
This should allow for the showers to progress to the west through
the afternoon and evening hours. The thunderstorms are mainly
garden variety type, with heavy rain and some gusty wind. Of
course, cant rule out a couple of strong storms here in Florida
either, but they should be isolated, if anything.
The trough will begin to weaken tonight and tomorrow as an upper
level high begins to build over the Bahamas. This should help to
keep most of the convective activity in the interior and lake
regions tomorrow through Thursday, with mostly diurnal type of
activity. 500mb temperatures through most of the week, look to be
fairly warm, with models showing around -6c. So continued
instability with showers and thunderstorms through the remainder
of the week.
the high will continue to build into South Florida late this week
from the Atlantic waters allowing for the continuation of the
drier air into the area from the east. The latest model guidance
continue to show the precipitable water value falling down to 1.2 to 1.4 inches
over South Florida late this week which is 2 Standard deviations
below the normal precipitable water value of 1.85 inches for this time of year.
Therefore...the shower and thunderstorm threat will be less
across South Florida late this week with the best coverage over
the Lake Okeechobee region probability of precipitation where the sea breezes collide.
The high will then weaken next weekend as a trough of low
pressure sets up over the eastern United States. This will allow
for the steering flow to become more southerly over South Florida
and allow for more deeper tropical moisture to return to the area.
Therefore...the scattered showers and thunderstorms will return
to South Florida for next weekend.
very weak surface gradient will allow for sea breezes to develop
along both coasts around 16z with rain showers/thunderstorms and rain expected to form along
the boundaries. Steering flow will also be very weak so placed
tempo groups in for all terminals although mostly VFR is
anticipated. The best window for convection would appear to favor
between 17-20z before activity shifts to the interior.
with high pressure building over the Atlantic waters, and a
trough of low pressure to the northwest will keep a generally
southerly to southeasterly flow over the South Florida water for
the next several days. While there is no significant increase in
wave heights through the week, sea may slightly build across the
Atlantic waters by middle to late week. Showers and thunderstorm are
also expected through the week, which may produce heavy showers,
gusty winds and a slight chance of waterspouts, mainly in the
Preliminary point temps/pops...
West Palm Beach 77 90 79 91 / 40 60 20 20
Fort Lauderdale 80 90 82 90 / 50 60 30 20
Miami 78 90 80 91 / 40 60 20 20
Naples 76 91 76 92 / 40 50 40 30