Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 061319
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
819 AM EST Sat Mar 6 2021

...MESOSCALE UPDATE...

.UPDATE...
As expected, some light rain has started to fall across portions of
the nature coast. However, radar is showing a lot more activity than
what appears to be actually reaching the ground. The 12Z sounding
data offers a lot of insight into why this is. From around 525mb up
to 350mb, the column is rather saturated. However, this is not the
case looking down lower, particularly in the 800mb-525mb layer. Even
closer to the surface below this layer, conditions are still looking
rather dry. After several days of dry weather, and RH values running
around 20% yesterday, it will likely take some time for the column
to become saturated enough for more widespread precipitation to
reach the ground.

The other factor is droplet size. Already mentioned is the lack of
moisture in the column. The other limiting factor is the relatively
weak forcing this morning (300-400 J/KG MLCAPE from RAP, NAM
soundings where precip is occurring). With such weak forcing,
droplets cannot really grow as there just isn`t enough force to keep
them suspended. It also appears that at least some of the convection
is elevated, with some spots showing nearly no SBCAPE in model
soundings.

However, we are expecting this to change throughout the morning, and
there are already indications that this is beginning to take place
across the Nature Coast. A few observation sites have begun to
report light rain in the last hour. This trend is expected to
continue, and we expect to see deepening convection throughout the
day as forcing increases with additional synoptic mechanisms and
diurnal heating. As such, the forecast looks on track right now.
Adjustments may be needed to POPs deepening on how things
continue to play out, but no major adjustments are anticipated at
this time.

&&

.AVIATION...
Conditions remain VFR for now, but an area of low pressure is
brining rain showers into the region. This could lead to
intermittent reductions to VSBYs and CIGs throughout the day, and
if these conditions appear to materialize, TAFs will be amended
as necessary. As the rain clears overnight and a cold front pushes
through, lower CIGs, followed by increasing winds are likely
towards tomorrow morning.

&&

.MARINE...
Rain showers are showing up across coastal waters, and will be an
issue throughout the day as an area of low pressure and attendant
cold front push through. This has also already begun to cause more
hazardous conditions for portions of coastal waters. Behind the
front, colder weather and stronger winds begin to filter into the
region, leading to increasingly hazardous boating conditions that
remain through at least mid-week.

&&

.Preliminary Point Temps/PoPs...
TPA  71  54  71  49 /  70  50   0   0
FMY  76  57  75  51 /  70  60   0   0
GIF  73  54  70  48 /  70  60   0   0
SRQ  73  55  72  49 /  60  40   0   0
BKV  70  48  70  39 /  80  60   0   0
SPG  70  56  69  53 /  70  50   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...Small Craft Advisory until 1 PM EST Sunday for Waters from
     Tarpon Springs to Suwannee River FL out 20 to 60 NM.

     Small Craft Advisory from 6 PM this evening to 1 PM EST Sunday
     for Coastal waters from Tarpon Springs to Suwannee River FL
     out 20 NM-Waters from Englewood to Tarpon Springs FL out 20
     to 60 NM.

&&

$$

Flannery


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