Area Forecast Discussion
Issued by NWS Miami, FL

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS62 KMFL 200040

Area Forecast Discussion
National Weather Service Miami FL
840 PM EDT Mon Mar 19 2018

Light southwest winds will continue overnight. Patchy fog may
develop over the Gulf coast and interior, but KAPF would likely
be the only TAF site affected, where vis could briefly drop below
5sm. Aft 20/1400Z, southwest winds will begin to increase over the
peninsula, generally around 10 KT, increasing to 15 KT around
20/1800Z. A frontal passage Tuesday evening may bring a few
showers to the region, but not confident enough to include in the
latest TAF package.


.PREV DISCUSSION... /issued 415 PM EDT Mon Mar 19 2018/


Tonight through midday Tuesday:
Main issue tonight will be potential for patchy fog and low clouds
developing after midnight as the atmosphere continues to moisten in
southwesterly flow ahead of an approaching shortwave trough and
front. Highest chances for fog will again be across the interior and
west coast region, but can`t be ruled out into the western part of
the east coast metro areas around sunrise.

After morning low clouds and fog dissipate, moderate southwest winds
and mostly sunny skies in the pre-frontal thermal ridge will be
favorable for relatively hot temperatures for March along the east
coast, with highs well into the 80s and even approaching 90 in a few
spots. On the Gulf side, surface winds blowing over the relatively
mild shelf waters and potential morning low clouds/fog should keep
high temperatures closer to 80 in that region.

Tuesday afternoon and overnight:
Models have come into better agreement that a shortwave trough in
the mid troposphere will swing across northern Florida late
Wednesday afternoon into the evening. There is an Enhanced Risk of
severe thunderstorms from the Storm Prediction Center centered over
the northern half of the peninsula where forcing associated with the
shortwave trough and front will be strongest.

Well ahead of the front during the afternoon hours over South
Florida, the atmosphere will be fairly unstable with modestly strong
wind profiles, but with no organized forcing mechanism to initiate
convection. This is why models are dry over our area Tuesday despite
the instability, so the forecast during the day will be dry. The
exception will be late in the afternoon and early evening over the
far northwest/Lake region where strong convection initiating to the
northwest might approach. SPC has delineated a marginal risk for
severe thunderstorms over that region. The primary threat will be
gusty winds due to the 40-50 knot low level jet over the area.

As the front moves further into south Florida during the later
evening and overnight hours, the shortwave trough will be departing
the region, bringing increasing subsidence and tending to suppress
deep moist convection with time. The weakening surface convergence
along the front may be just enough for an isolated gusty shower to
persist as the front reaches southeast sections overnight, but
coverage is expected to be very low.

Wednesday and beyond:

A dry, mild air mass will overspread the region behind the front.
With dewpoints falling into the 30s most areas, there will be a
fairly large diurnal temperature range Thursday and Friday with
cool lows in the mid 40s-mid 50s and highs in the 70s under sunny
skies. Winds veer around to easterly over the weekend as the
center of the high pressure moves into the western Atlantic,
bringing a gradual warm up and slightly more humid air but still
little to no rain chance into early next week.



Southwest winds will steadily increase over the local waters Tuesday
ahead of an approaching front. Small Craft Advisories may be
required in later forecasts starting Tuesday afternoon. Behind
the front Wednesday, winds veer around to west and then northwest,
remaining in the 15-20 knot range. A 1-2 foot swell combined with
wind waves may bring 7-8 foot wave heights, locally higher, to
the local Gulf waters late Tuesday night into Wednesday, with a
similar setup in the Atlantic waters on Thursday. Conditions
steadily improve Friday into the weekend as high pressure moves
over the region.


There will be at least a moderate risk of rip currents at the Gulf
Beaches Tuesday with moderately strong onshore winds, and the
enhanced risk may continue Wednesday into Thursday with moderate
northwest winds and a 1-2 foot swell. An enhanced risk of rip
currents is also possible Thursday night into the weekend at the
Atlantic beaches due to a 1-3 foot swell affecting the coast.


Expect very good to excellent dispersion Tuesday midday-afternoon
with moderately strong southwest winds ahead of a cold front. A
very dry air mass will move into the region behind the cold front
Wednesday. Minimum RH Wednesday afternoon will be in the 30-35
range over parts of the interior, and in the 20-30 percent range
over most of the region Thursday and Friday afternoons, before
increasing to 35 percent or higher this weekend. At this time,
winds above 15 mph are not expected to coincide with the low RH
periods, so headlines are not required.


Near record highs are possible along the east coast Tuesday.

City           Tuesday Forecast / Record high (years)
Miami          88 / 89 (2008)
Ft. Lauderdale 87 / 91 (1965)
W. Palm Beach  88 / 88 (1988 and previous years)


West Palm Beach  68  88  62  78 /  10  10  30   0
Fort Lauderdale  70  87  65  79 /   0   0  20   0
Miami            70  88  65  80 /   0   0  20   0
Naples           69  80  63  73 /  10  40  30   0



FIRE WEATHER...22/KS CLIMATE...22/KS is the U.S. government's official web portal to all federal, state and local government web resources and services.