Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 220003

Area Forecast Discussion
National Weather Service Miami FL
803 PM EDT Thu Jun 21 2018

Showers and thunderstorms are gradually winding down this evening
across Miami-Dade and for northern areas, including Glades and
Palm Beach Counties as well as Lake Okeechobee. A few showers and
thunderstorms are still possible into the evening hours, mainly
for eastern and northern portions of South Florida. By late
evening, most of the showers over land are likely to have
dissipated. Showers and storms will be possible over the Atlantic
waters through the night. Based on the latest short term models,
only minor adjustments were made to PoPs for tonight.


.PREV DISCUSSION... /issued 743 PM EDT Thu Jun 21 2018/

The weather should remain dry over most of the taf sites tonight
into Friday morning. The only exception to this is over the KMIA,
KTMB, and KOPF taf sites where VCSH will continue through 02Z this
evening for ongoing showers. The east coast taf sites will then
see VCTS after 18Z on Friday for afternoon convection. The winds
will remain at 10 knots or less from the west southwest direction
tonight into Friday at most of the taf sites, except for KPBI and
KFLL where the direction could go to southerly after 18Z due to
the east coast sea breeze. The ceiling and vis will also remain in
VFR conditions, but could fall into IFR conditions with activity
Friday afternoon.


PREV DISCUSSION... /issued 350 PM EDT Thu Jun 21 2018/

Short-medium range (through the weekend): Numerous thunderstorms
have been occurring over interior South FL this afternoon. Expect
this activity to gradually migrate eastward through the late
afternoon hours. In the meantime, additional showers and storms
will be forming closer to the east coast metro areas as the west
coast sea breeze has made it most of the way across South FL and
is now colliding with the east coast sea breeze in Miami-Dade and
shortly in Broward. A few strong storms are possible with brief
gusty winds, frequent lightning and heavy rainfall.

Not much has changed in the forecast philosophy through Saturday.
Friday and Saturday will be dominated by storms forming over the
interior during the early afternoon along with sea breeze
collisions and activity migrating eastward in the late afternoon.
Low-level wind flow will still be westerly on Friday and the first
part of Saturday. Later on Saturday into early Sunday, winds
become lighter and more variable.

PWATs will continue to increase this evening, and will be near 2
inches for portions of the area at least through Monday. GFS
suggests slightly higher PWATs across the eastern half of South FL
compared to the west Friday through Sunday. PoPs as high as 60
percent are forecast for portions of interior/eastern South FL on
Friday afternoon, with 70 PoPs for some areas Saturday through
Monday. Expect numerous thunderstorms, especially over the interior,
during the afternoons.  The east coast will likely get in on the
activity for a few hours each late afternoon as well.

In terms of the heat, expect another day of heat index values as
high as 105 across much of South Florida on Friday.  However, due to
increased cloud cover and moisture over the weekend, it no longer
appears that heat index values will be much above 100 for too long
on Saturday-Sunday.

Long term (early next week): A large amplitude trough moving over
the U.S. East Coast Sunday and Monday along with weak ridging
further south over the western Atlantic and Gulf will lead to
southeasterly winds for us early next week. This will continue to
bring enhanced moisture into the region. Therefore, expect
elevated rain chances to continue into next week.

Winds generally 5 to 12 knots and seas 2 feet or less will
prevail through the weekend. The only concern to watch out for is
thunderstorm activity. For the Gulf, only isolated activity is
possible through Saturday, with increasing rain chances on Sunday.
For the Atlantic, storm coverage will be scattered through the
weekend, with greatest coverage during the evenings.

West Palm Beach  76  91  75  89 /  40  60  30  50
Fort Lauderdale  78  91  78  89 /  30  60  30  60
Miami            78  92  78  90 /  30  60  30  60
Naples           78  91  78  91 /  10  20  10  40



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