Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS62 KMFL 270706
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
306 AM EDT Tue Jun 27 2017

.DISCUSSION...

NEAR TERM /THROUGH 6 PM TUESDAY EVENING/... 

As of 305 AM EDT...A weak frontal boundary continues to remain 
draped across north/central Florida, with broad longwave troughing
across much of the eastern third of the CONUS. A ridge of high 
pressure extends southwestward from Bermuda across South Florida 
helping to keep a light east/southeasterly flow in place. Earlier 
overnight thunderstorms over the Gulf waters and portions of the 
Gulf Coast continue to dwindle, with isolated to widely scattered 
showers over the Atlantic waters and portions of the east coast. 
This trend will continue through daybreak, with areas primarily 
west of the Florida Turnpike trending dry, with the best chances 
for showers/storms east and over the Atlantic waters.

For today, the aforementioned frontal boundary to the north will 
move little, with the longwave trough and a secondary upper-level 
low gradually breaking down the Bermuda ridging across the region. 
This pattern will keep South Florida relatively void of any major 
synoptic features and allow for local mesoscale sea breeze effects 
to drive the day's weather. With light flow in place, expect both 
the Atlantic and Gulf sea breezes to fully develop and be the 
primary foci for scattered showers and thunderstorms beginning in 
the late morning hours and persisting through much of the afternoon. 

Latest mesoscale and CAM guidance depicts two areas of convective 
initiation, one across the far southern interior and the second 
along the leading edge of the Gulf sea breeze. While initiation may 
not necessarily occur in these areas, much of the convective 
activity will be focused across the interior, with a trend towards 
portions of the east coast metro with a light southwesterly steering 
flow. Mid-level temps will be around normal for this time of year, 
so expecting most of the activity to be general thunder, although 
some storms may briefly be strong along enhanced boundary 
collisions. The main threats will be frequent lightning and locally 
heavy rain, with brief gusty winds also possible with the stronger 
storms.

High temperatures will reach 90 for most areas, with lower to mid 
90s in the interior. The summer heat will be on with heat indices 
likely reaching into the lower 100s across many areas as well, 
especially south.

SHORT TERM /6 PM TUESDAY EVENING THROUGH THURSDAY NIGHT/...

The short term period will continue to see the frontal boundary to 
the north gradually wash out with time, as upper-level energy across 
the Northeast helps keep the Bermuda high suppressed and a weak flow 
pattern dominated by sea breezes in place across South Florida. 
Other than some minor surges in moisture through the period, the 
pattern will generally remain stagnant across the immediate region, 
with scattered to locally numerous showers and thunderstorms 
primarily focused in interior areas during the afternoon and evening 
hours. By Thursday, the Bermuda high will begin to restrengthen and 
mark a transition to a more moderate easterly flow regime.  

Temperatures will be near to slightly above normal with highs in the 
upper 80s/near 90 along the coasts to lower and mid 90s in the 
interior. Low temperatures will generally be in the 70s.

LONG TERM /FRIDAY THROUGH MONDAY/...

The long term period will continue to see the reestablishment of the 
Bermuda high, along with a predominately summertime easterly flow 
regime. This pattern will feature typical sea breeze development 
during the afternoon hours, with scattered showers and thunderstorms 
favored over the interior and Gulf Coast, with nighttime activity 
favored over the Atlantic waters and east coast. With the Bermuda 
high becoming well established, subsidence in the mid-levels will 
lead to near of slightly below normal PWATs for this time of year, 
helping to keep rain chances towards seasonal norms. Temperatures 
will be near normal during the long term period.

&&

.MARINE...
Generally good boating conditions will prevail across the local 
waters for the next several days with light southeasterly flow. 
Local sea breezes may briefly enhance winds near the coast to 10-15 
knots during the afternoon, from the southeast along the Atlantic 
coast and west/southwest along the Gulf coast. Additionally, locally 
erratic winds along with lightning will be possible in and around 
thunderstorms which are expected to be isolated to widely scattered 
in coverage. Seas will be 3 feet or less heading into the 
weekend.

&&

.AVIATION...
Decaying convection should lead to -RA at Naples until 630-8z,
otherwise only isolated showers /not worthy of TAF mention/
expected through noon. Thereafter, expect scattered showers and
some thunderstorms through sunset. Risk of thunder isn't
exceptionally high, so considered converting VCTS to VCSH at
east-coast terminals. At KAPF, where rain chances are lowest, did
maintain only VCSH for now. Dont think there will be entire 6-10
hour period of VCTS, but right now, timing uncertainties preclude
a narrower window.

Light winds /possibly drainage AOB 5 KT/ through sunrise, then
generally SE at 8-12 KT. Wind will calm again by midnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  91  75  90  78 /  50  30  50  30 
Fort Lauderdale  90  78  91  79 /  40  40  50  30 
Miami            91  78  92  79 /  50  40  60  30 
Naples           89  76  91  76 /  30  20  50  30 

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.

National Weather Service Glossary of Abbreviations