Flood and Heavy Rain in Florida, July 24, 2019

Area Forecast Discussion
National Weather Service Jacksonville FL
932 AM EDT Wed Jul 24 2019

...LOCALLY HEAVY RAINFALL POSSIBLE TODAY...

.UPDATE...

Currently (845 am), an area of heavy rain showers is moving across
SE Georgia producing widespread 0.5-1 inch amounts with localized
amounts of 2-3 inches in the Folkston area. These showers will
continue to move northeast within SW mean flow of 10-15 knots
ahead of a frontal boundary. Additionally, across NE Florida,
scattered showers have moved from the Gulf coast to the NE across
the peninsula. This activity is expected to continue throughout
the morning hours. Across SE Georgia, the frontal boundary is
expected to gradually sink southward toward the FL/GA border
before stalling. With southwest flow ahead of the front,
convergence along the boundary suggests the threat for localized
heavy rainfall somewhere near to the I-10 corridor. The 12Z
sounding observed a deep tropical airmass with PWAT values at 2.34
inches. This also supports the threat for localized heavy rainfall
especially where deep convection is able to take advantage of the
entire saturated column. GOES-16 mesosector analysis shows fairly
widespread mid and upper level clouds across the area with some
patches of sun across NE Florida. This will initially help with
some modest heating and instability growth, allowing scattered
showers and thunderstorms to continue south of I-10. As the front
works southward, additional development is expected along the
boundary near the FL/GA border. High-resolution models suggest
the idea of slow moving thunderstorms early this afternoon along
the boundary, leading to localized heavy rainfall. Because
instability is expected to be fairly limited due to cloud cover,
the progression of the front southward will be important to
realizing this threat.

Temperatures will be below average this afternoon due to the
abundant cloud cover and chances for precipitation. Temps struggle
into the low 80s by early afternoon before dropping into the upper
60s and lower 70s by early Thursday morning.

Precipitation chances remain during the overnight, but most
activity should be focused along the Gulf coast as southwest flow
ahead of the stalled front continues.

&&

.AVIATION...

A frontal boundary moving southward across SE Georgia favors
southwest flow leading to multiple rounds of showers and
thunderstorms for several TAF locations. Ceilings will vary with
showers and thunderstorms this morning with increasing coverage
this afternoon, especially along I-10 and southward. Coverage near
SSI is expected to decrease by late morning with VC activity
possible this afternoon along the coast. Winds shift out of the
northeast during the afternoon for Duval TAF sites as the front
moves south. The front stalls over north-central FL late this
afternoon with continued precipitation chances for all FL TAF
sites into the overnight period.

&&

.MARINE...

Northeast winds will increase behind the frontal boundary late
this morning and into the afternoon. Abundant moisture in SW flow
favors showers and thunderstorms over area waters throughout the
afternoon and evening. Winds are expected to be between 10-15 with
seas 2-3 feet.

Rip Currents:  A low-end moderate risk will develop late this
afternoon at the northeast Florida beaches as winds become north-
northeasterly during the outgoing high tide. A low risk should
continue at the southeast Georgia beaches today, followed by a
moderate risk at all beaches on Thursday due to onshore winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  85  68  90  68 /  40  10  20  10
SSI  82  76  85  74 /  60  30  30  30
JAX  83  71  86  71 /  80  40  50  30
SGJ  84  76  85  72 /  90  60  60  40
GNV  83  72  85  70 /  90  50  70  50
OCF  83  71  86  70 /  80  50  70  50

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&

McGinnis