Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 280533

Area Forecast Discussion
National Weather Service Miami FL
133 AM EDT Wed Jun 28 2017

Although isolated showers cant be ruled out through late morning,
expected coverage and confidence in timing are not high enough to
warrant inclusion in 6z TAF issuance. By midday, Atlantic and Gulf
sea breezes will begin to penetrate inland, and scattered showers
and thunderstorms should develop in association with these
boundaries. Thus, VCTS in place through 0z, and brief restrictions
are quite possible in/near any convection. Activity should
diminish in intensity by late evening, but guidance suggests
gradually moistening atmosphere, so have placed VCSH for eastern
terminals through the end of the period.

Light winds through mid-morning, then SE wind around 10 KT,
calming again after sunset.


.PREV DISCUSSION... /issued 804 PM EDT Tue Jun 27 2017/

IR Satellite imagery shows convection dwindling across the CWA
with cloud tops slowly warming. However, leftover boundaries from
this evenings storms may trigger a few showers and storms during
the next several hours. Another feature of interest is the line of
thunderstorms pushing northward off of the Cuban coast. Short
term models show outflow from this activity possibly interacting
with boundaries near our coast early Wednesday morning. If this
occurs, additional thunderstorms may develop over the Atlantic
waters. Will continue to monitor through the night. Previous
forecast package appeared on track, so besides loading in the
latest wind and sky guidance, did not have to teak other forecast

PREV DISCUSSION... /issued 358 PM EDT Tue Jun 27 2017/

Latest water vapor imagery loop shows a cyclonic spinning low
over New York State with a longwave trough draped along the
the mid-Atlantic. Surface analysis indicates a east- west
oriented stationary boundary sitting stagnant across north-
central Florida. This feature has managed to push the Bermuda high
eastward, away from our region, resulting in near natural flow.
Thus, well established sea breezes have already developed and
continue to push inland, towards the interior. Satellite derived
PWAT values range from 1.7 inches in the southern peninsula to
near 2.0 inches further north. These values are slightly higher
than climo and more than sufficient for heavy, slow moving storms.
With a modified DCAPE of 1,400 J/KG, wet microbursts producing
strong wind gusts are also a possibility. Short term model
guidance progs convection to propagating across the interior
through the early evening. After diurnal heating ceases, activity
should begin to wane. SPC has placed a marginal risk of severe
weather from West Palm Beach to Lake Okeechobee, so will continue
to monitor for the remainder of the day. Tomorrow should be a
similar set up, with not much changing synoptically. Light flow
will again lead to sea breeze convergence inland from the coasts.
As the day progresses, outflow boundaries will shift most of the
convection towards the interior. Maximum temperatures tomorrow
are forecast to hover in the upper 80s along the coasts, with
lower 90s inland. These values are around normal to slightly above
normal for this time of year.

Late next week into the weekend: By Thursday, both the GFS and
ECMWF prog the aforementioned front to wash out and retreat
northward. This will allow surface high near Bermuda to once again
increase in strength. Stronger southeast flow will begin to
concentrate afternoon convection back towards the western
interior, as sea breeze collision shifts west. Friday into this
weekend, a more typical summertime regime reestablishes itself.
Long range models show an elongated high building aloft over the
peninsula with surface high building near Bermuda. This pattern
typically brings persistent southeast flow. Afternoon convection
will most likely occur in the western interior and Gulf coast with
night showers affecting the east coast metro region. PWATs
decrease slightly below climo during this time frame, so not
anticipating much in the way of significant heavy rain events.

MARINE...Winds and seas should remain below small craft advisory
criteria across the local waters through the forecast period with
mainly light southeasterly flow prevailing. Sea breezes may
enhance winds near the coast to 10-15 knots at times each
afternoon. Only exception will be with any thunderstorm that
forms, which will bring brief periods of strong gusty winds and
rough seas. Waterspouts are also possible, especially in the
morning hours, mainly over the Atlantic waters. Seas will be 3
feet or less heading into the weekend.

West Palm Beach  91  78  91  78 /  50  30  50  40
Fort Lauderdale  90  79  91  80 /  50  30  40  30
Miami            92  79  91  79 /  50  30  40  30
Naples           91  76  91  76 /  40  20  50  40



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