Special Weather Statement, NWS Melbourne, FL

Area Forecast Discussion
National Weather Service Melbourne FL
10 AM EDT Mon Jun 26 2017

.UPDATE...
A few more clouds across central FL this morning that has slowed
heating, but most have dissipated in last hour. Morning soundings
show somewhat cooler air has moved into place as upper trough to the
north has inched just a bit closer. H5 temps running now about -7C
at both XMR and TBW, still there is a bit of a capping inversion
around 650mb that convection will have to overcome. PWAT values now
1.8-1.9 inches across central FL. GOES PW depiction refines the
gradient that exists through area with the near 2 inch values
restricted to an area from north of MLB and ISM, and values trailing
to around 1.5 inch along the Treasure coast.

These observations indicate current forecast on track with best
storm coverage over the north and interior due to boundary
interactions. Both recent HRRR and local ARW-WRF are also consistent
with this scenario of storm concentration greatest with breeze
boundary collision along the I 4 corrider. This is similar to what
happened yesterday but expect somewhat higher coverage due to cooler
temps aloft. Steering flow is still weak, but shows a little more
potential for activity to work back towards the coast north of the
Cape. Temp forecast on track.

&&

.AVIATION...
Previous... Generally VFR through the forecast period outside of
brief reductions due to afternoon shower and thunderstorm activity.
Greatest coverage of SHRA/TSRA anticipated from KMLB to the north
and west with lower chances along the Treasure Coast terminals (KVRB-
KSUA). Have introduced tempo groups where chances are highest; users
should monitor for timing adjustments as we monitor trends in
convective development through the day. Activity should gradually
diminish between sunset and midnight. Winds generally 10 knots or
less outside of gusty winds due to thunderstorm activity.

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&

Blottman

Hazardous Weather Outlook...UPDATED
National Weather Service Melbourne FL
1032 AM EDT Mon Jun 26 2017

AMZ550-552-555-570-572-575-FLZ041-044>047-053-054-058-059-064-141-
144-147-270245-
Flagler Beach to Volusia-Brevard County Line 0-20 nm-Volusia-
Brevard County Line to Sebastian Inlet 0-20 nm-
Sebastian Inlet to Jupiter Inlet 0-20 nm-Flagler Beach to Volusia-
Brevard County Line 20-60 nm-Volusia-
Brevard County Line to Sebastian Inlet 20-60 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Inland Volusia County-
Northern Lake County-Orange-Seminole-Southern Brevard County-
Osceola-Indian River-Okeechobee-St. Lucie-Martin-
Coastal Volusia County-Southern Lake County-
Northern Brevard County-
1032 AM EDT Mon Jun 26 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL FLORIDA.

.DAY ONE...TODAY AND TONIGHT.

.THUNDERSTORM IMPACT...
An approaching frontal boundary and increased moisture in the
atmosphere will produce a higher coverage of afternoon showers
and thunderstorms. Initial development of isolated lightning
storms is expected along the east coast sea breeze as it pushes
inland from the coast early this afternoon. Coverage and intensity
of thunderstorms will increase late this afternoon and early
evening over the interior, especially along the Interstate 4
corridor and Osceola county. Some of the storms will push back
toward the Volusia and Brevard County coasts. The primary hazards
will be cloud to ground lightning, gusty downburst winds, and
heavy rainfall. Storm motion will be generally toward the
northeast around 10 mph but thunderstorms that form as a result
of boundary collisions will exhibit slow and erratic movement.

.FLOOD IMPACT...
Slow moving lightning storms will be capable of producing locally
heavy rainfall late this afternoon and this evening across parts
of Lake, Volusia, Seminole, Orange, Osceola, and Brevard
counties. Rainfall amounts of 2 to 4 inches will be possible in a
few spots which will cause temporary flooding of roadways and low
lying areas.

.RIP CURRENT IMPACT...
An east swell will produce a moderate risk of rip currents at the
beaches of east central Florida. Always swim within sight of a
lifeguard.

.MARINE THUNDERSTORM GUST IMPACT...
Scattered lightning storms will be capable of producing dangerous
lightning strikes and gusty downburst winds late this afternoon
and this evening. Most of the storms will stay over land and
affect inland lakes but there is chance for a few storms or their
outflows to push back to the Volusia and Brevard coasts.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.
Scattered lightning storms are expected each afternoon this week,
with the highest storm coverage forecast through Tuesday as a
weak frontal boundary pushes into the area and stalls. The primary
threats will be dangerous lightning strikes, gusty winds and
locally heavy rain.

.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed today, however spotters are
asked to report rainfall amounts of greater than 3 inches or
observed flooding.

15

Special Weather Statement
National Weather Service Melbourne FL
137 PM EDT MON JUN 26 2017

FLZ041-141-261830-
Inland Volusia County FL-Coastal Volusia County FL-
137 PM EDT MON JUN 26 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL VOLUSIA COUNTY UNTIL 230
PM EDT...

At 134 PM EDT, Doppler radar was tracking a strong thunderstorm NEAR
Daytona Beach Airport, moving northeast at 10 TO 15 mph. Additional
developing strong storms will affect areas near Deland and New
Smyrna Beach. Locally heavy rain and cloud to ground lightning will
accompany these storms.

Winds GUSTS UP TO 40 mph will be possible with this storm.

Locations impacted include...
Deltona, Daytona Beach, Port Orange, Ormond Beach and DeLand.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 2910 8090 2902 8085 2894 8099 2893 8124
      2897 8137 2899 8136 2899 8137 2903 8141
      2918 8138 2927 8121 2927 8115 2930 8115
      2935 8103
TIME...MOT...LOC 1734Z 237DEG 16KT 2917 8106

15

Special Weather Statement
National Weather Service Melbourne FL
221 PM EDT MON JUN 26 2017

FLZ045-144-261915-
Orange FL-Southern Lake County FL-
221 PM EDT MON JUN 26 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN LAKE AND WESTERN
ORANGE COUNTIES UNTIL 315 PM EDT...

At 220 PM EDT, Doppler radar was tracking a strong thunderstorm over
Clermont, or near Groveland, moving east at 15 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Orlando, Apopka, Ocoee, Winter Garden and Maitland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 2879 8152 2878 8144 2873 8143 2871 8144
      2871 8146 2864 8146 2864 8140 2846 8134
      2840 8171 2868 8183
TIME...MOT...LOC 1820Z 252DEG 6KT 2854 8177

Johnson