FXUS62 KJAX 181334
Area Forecast Discussion
National Weather Service Jacksonville FL
930 AM EDT Sat Aug 18 2018
Sfc analysis shows near normal position of the high pressure ridge
over north central FL area. Deep 1000-500 mb flow remains southwest
(JAX sounding showing 240 deg at 9 knots) with moisture levels near
or below normal and the driest air noted in GOES imagery over
central FL with min value of about 1.1 inches there, but 1.9 inches
in southeast GA.
At this time, only scattered mid to high levels clouds which are
thin enough in most areas for good heating today with scattered to
broken cu forming by late morning. Highs today forecast in the lower
to mid 90s, perhaps a little warmer than yesterday given latest
sounding temps. With the drier air from central FL lifting slowly
northward, convection chances are diminished from prior days and
will keep inherited 20-30 percent chances for northeast FL, though
southeast GA will have higher POPs around 30-50 percent given PWATs
there closer to normal at 1.7 to 2 inches. There is also some weak
shortwave energy pushing through srn GA later in the day helping to
provide some synoptic lift there. West coast and east coast sea
breeze should be active today with the east coast sea breeze delayed
until around 17z-18z given southwest flow. An isolated strong to
severe pulse storm remains possible today with frequent to excessive
lightning, and given dry air aloft enhances the potential for
downburst winds up to 40-60 mph. For the update, have tweaked max
temps up a deg or so and adjusted POPs toward latest guidance and
VFR conditions prevail. Light southwest flow near 5-10 kt expected
today with wind shift to southeast for coastal TAFs with the east
coast sea breeze. Light winds will become southwest again at all
TAFs by late evening and overnight. Overall, a low chance of showers
or t-storms at the terminals for today so vicinity wording starting
around 18z-19z looks good at this time.
Southwest winds near 5-15 kt will shift to the south and southeast
this afternoon near 10-15 kt. Seas mostly around 2-3 ft with wind
waves about 4 seconds and weak east swells at about 8 seconds. Looks
like coastal waters, except inland waterways, will remain nearly
Rip Currents: Moderate risk today NE FL coast and lower risk for Low
risk for SE GA today. Surf conditions show 1-2 ft per latest obs and
.PRELIMINARY POINT TEMPS/POPS...
AMG 91 73 91 73 / 40 30 40 20
SSI 89 76 90 76 / 20 20 20 20
JAX 93 74 93 74 / 30 20 20 10
SGJ 91 75 90 74 / 20 20 20 20
GNV 93 74 93 74 / 30 20 20 10
OCF 94 73 93 73 / 20 10 30 10
FXUS62 KMLB 181416
Area Forecast Discussion
National Weather Service Melbourne FL
1015 AM EDT Sat Aug 18 2018
Latest RAP40 analysis showing the axis of the Bermuda Ridge draped
over central FL, resulting in a southerly breeze AOB 10KTS from the
sfc thru 10KFT. GOES PWat product showing a pocket of very dry air
drifting north acrs central FL, with core values arnd 1.00". Mrng
RAOBS map this dry air quite well...PWat values btwn 1.25"-1.50" at
KXMR/KTBW, increasing to 1.75"-2.00" at KJAX/KMFL. RAP40 analysis
picking up on the dry air as well, H100-H70 mean RH values btwn 50-
60pct north of Cape Canaveral/Lake-K, increasing to 70-80pct over
the Treasure Coast/Lake-O region.
Thermodynamic instability is modestly steep...H70 temps btwn 9-10C
and H50 temps arnd -7C are yielding lapse rates btwn 6.0-6.5C/KM
thru the layer. Dynamic support is quite weak, however, as H85-H30
omega and H30-H20 divergence values are negligible. There is a
pocket of enhanced H85-H50 vorticity over Polk/Osceola counties
associated with a weak ripple in the mid lvl wind fields, but this
feature is planted firmly in the center of the dry air, so any PVA
that may result will be starved of moisture.
The east coast sea breeze has formed from the Cape southward...isold
shras dvlpg along its boundary over the Treasure Coast. Given the
moisture profile, diurnal precip will be largely confined to areas
south of Cape Canaveral and Lake-K. To the north, dry air will
smother any large scale PoPs. A few shras/tsras psbl late this aftn
along and north of I-4, but will require the east/west coast sea
breeze merger to spark them. Dry air and limited cloud cover will
allow max temps over the interior from Osceola Co. northward to warm
into the M90s. Early formation of the east coast sea breeze will
keep coastal max temps in the L90s...Okeechobee Co. in the L90s as
well as the prevailing srly flow will place them in the lake shadow.
Sfc Winds: Thru 18/15Z...S/SE 4-8KTS. Btwn 18/15Z-18/17Z...coastal
sites bcmg E/SE 7-11KTS. Btwn 18/17Z-18/19Z...interior sites bcmg
Vsbys/WX/Cigs: Thru 18/16Z...E of KMLB-KOBE isold MVFR shras. Btwn
18/16Z-18/19Z...S of KMLB-KSEF sct MVFR shras/IFR tsras. Btwn 18/19Z-
18/22Z...S of KISM-KTIX sct MVFR shras/IFR tsras. Btwn 18/22Z-
19/02Z...S of KISM-KTIX sct MVFR shras/IFR tsras...N of KISM-KTIX
isold MVFR shras/IFR tsras.
Bermuda Ridge axis over central FL will maintain a light to gentle
S/SE breeze over the lcl Atlc thru daybreak Sun...bcmg E/SE near the
coast this aftn concurrent with the east coast sea breeze. Seas AOB
2FT...up to 3FT in the Gulf Stream north of Sebastian Inlet arnd
midnight tonight. Isold shras/tsras, mainly in the Gulf Stream.
FXUS64 KMOB 181152
Area Forecast Discussion
National Weather Service Mobile AL
652 AM CDT Sat Aug 18 2018
.DISCUSSION...Updated for latest aviation discussion below.
12Z issuance...Scattered to numerous SHRA along with a few TSRA
will continue to develop across the region through the day today.
Localized MVFR to IFR conditions will be possible near heavier
convection. VFR conditions should otherwise prevail outside of
this activity. Light winds early this morning should become south
to southwest 5-10 knots later this morning into this afternoon.
.PREV DISCUSSION... /issued 445 AM CDT Sat Aug 18 2018/
NEAR TERM /Now Through Saturday night/...A mid to upper level
trough axis continues to extend southwestward from the Great
Lakes/Ohio Valley region to the Lower Mississippi Valley and
central Gulf Coast region early this morning. A surface ridge of
high pressure meanwhile remains oriented from the western Atlantic
to the east central Gulf of Mexico. Abundant deep layer moisture
remains entrenched across our forecast area early this morning,
with high precipitable water values averaging between 2" and 2.2".
So far radar has remained rather quiet, but isolated to scattered
rain showers are finally starting to form near the MS coast just
west and southwest of our CWA as of 4 A.M. CDT.
Somewhat of a challenging forecast today in terms of where the
regions of best convective coverage will occur along with the
associated timing. Our general expectation is that a trend similar
to yesterday will materialize with increasing coverage of showers
and a few thunderstorms near coastal portions of southwest AL and
across the western FL panhandle early this morning, followed by
gradual development of showers and storms farther inland across
south central and southwest AL and eventually much of southeast MS
late this morning into this afternoon. In terms of POPs, have
increased coverage to 60-70% this morning mainly southeast of a
Mobile to Andalusia line, with likely POPs then spreading inland
across the remainder of the region during the afternoon.
Precipitable water values will continue to average between 2" and
2.25" through this afternoon, so the heavier showers and storms
will be efficient rainfall producers with potential for localized
ponding of water on area roadways and perhaps localized flooding
of low lying areas. Short range guidance also indicates a region
of surface based CAPE values up to 2000-3000 J/KG across portions
of southeast MS and interior southwest and south central AL this
afternoon, so a few stronger storms may develop within this region
capable of producing localized strong wind gusts over 40 mph
along with frequent cloud to ground lightning strikes. Scattered
showers and thunderstorms may linger into this evening over
interior southeast MS and southwest AL before coverage gradually
diminishes. A few showers and storms may then re-develop late
tonight into the pre- dawn hours of Sunday, mainly near the coast.
Otherwise, temperatures today should be fairly similar to
readings recorded Friday with highs in the mid 80s to around 90.
Another seasonably warm and muggy night is expected tonight. /21
SHORT TERM /Sunday Through Monday night/...An upper high pressure
system off the southeast conus coast will remain in place through
the short term, while an upper closed low pressure system over the
central Great Plains moves eastward and evolves into an open wave
before reaching the Great Lakes. The southern extension of the
open wave will reach into eastern Texas by late Monday night. An
associated surface low pressure system will form across the
central plains by Sunday evening, and then lift east-northeast
across the lower midwest. A surface ridge of high pressure
extending from the western Atlantic across the Florida peninsula
and Gulf of Mexico will remain in place, keeping a light southerly
and moist wind flow across the forecast area.
Will keep numerous to definite showers and thunderstorms across
the area on Sunday, with scattered to numerous showers forecast on
Monday. While mainly isolated to rain-free conditions are
forecast for much of the overnight periods, there is the potential
of scattered showers and thunderstorms affecting much of the
forecast area Sunday night after midnight as over-running in the
low levels brings the gulf precipitation inland. Additional
widespread rainfall amounts through the short term will range
from 0.4 to 0.7 inch, with isolated locations affected by the
stronger thunderstorms picking up to two inches of rain. /22
LONG TERM /Tuesday Through Friday/...The southern extension of
the upper level trough to our west will approach and pass over
the region through midweek, followed by upper high pressure
building in from the north. As a result, kept scattered to
numerous daytime showers and thunderstorms in the forecast through
midweek. The best chance of overnight precipitation should occur
Tuesday night as a weak frontal boundary associated with the
lifting center of low pressure enters into the forecast area and
possibly moves south of the coast. Drier conditions are set for
Thursday and Friday. /22
MARINE...A surface ridge of high pressure will continue to extend
from the western Atlantic through the central Gulf of Mexico
through early next week. This feature will maintain a light to
occasionally moderate south to southwest flow over the marine area
through Tuesday. There is some potential for a weak front to
bring offshore flow by next Wednesday, but this is still several
days out. Seas remain around 2 feet over the next few days. Winds,
waves and seas will be locally higher near showers and
This product is also available on the web at:
FXUS62 KTBW 181319
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
919 AM EDT Sat Aug 18 2018
Mid/upper-level ridging remains over the state this morning with a
band of drier air clearly noted on water vapor imagery. This drier
air is lingering right over the central part of the peninsula and is
forecast to persist through much of the day. At the surface, the
subtropical ridge axis is stretched across the north-central
peninsula, with a light southeast low-level flow in place across the
forecast area. These winds will turn onshore in the afternoon as the
sea breeze circulation gets going, but the dry air will keep rain
chances low for most areas. The exception is over the southwest
Florida region, where the air is not as dry. The overall forecast is
on track with just a few minor tweaks made this morning.
VFR conditions are expected outside of any thunderstorm activity
this afternoon. Best chances are for KLAL as well as KPGD, KFMY, and
KRSW. Chances are too low to mention for the other sites. Light and
variable winds this morning will become more southwest to west along
the coast this afternoon with the sea breeze.
High pressure will remain over the region for the next several days.
Winds and seas will be briefly higher in or near thunderstorms, but
otherwise no headlines are expected.
.Preliminary Point Temps/PoPs...
TPA 92 78 91 78 / 10 10 20 20
FMY 91 76 91 76 / 50 10 30 20
GIF 95 75 92 75 / 30 20 50 30
SRQ 89 77 89 77 / 10 10 10 20
BKV 93 73 92 75 / 10 10 30 20
SPG 92 79 90 78 / 10 10 10 20
FL...Beach Hazards Statement through this evening for Coastal
Beach Hazards Statement through Monday evening for Coastal
Charlotte-Coastal Lee-Coastal Sarasota.
FXUS62 KTAE 181331
Area Forecast Discussion
National Weather Service Tallahassee FL
931 AM EDT Sat Aug 18 2018
Precipitation coverage continues to increase across the western
FL Panhandle and will expand northeast this afternoon. Forecast
is on track with no major changes.
.PREV DISCUSSION [644 AM EDT]...
.NEAR TERM [Through Today]...
An upper level trough will persist over the area between a ridge
trying to build in from the west and the Bermuda ridge to our east.
Global models show a southwest to northeast oriented deep plume of
moisture cutting through all but the southeast Big Bend of our CWA.
Forecast PW at Tallahassee this afternoon is 2.2" compared to 1.7"
at Cross City. This moisture combined with daytime heating and sea
breeze interaction will result in scattered to numerous showers and
thunderstorms. PoPs today will be tapered highest(70%) west to
lowest (20-30%) across the southeast Big Bend.
.SHORT TERM [Tonight Through Monday]...
The general upper-level northern stream pattern will be driven by
a couple of shortwaves through early next week. The first will
move through the Ohio Valley and Mid-Atlantic Sunday through
Sunday night, with a brief period of ridging building in ahead of
the second wave forecast to be in the Middle Mississippi Valley
towards the end of the period. At the same time, a TUTT is
forecast to move over the Florida Straits and across the extreme
southern GOMEX. Favorable upper-level forcing on the NW quadrant
of the TUTT, combined with deep layer southwesterly flow will
result in an early start to shower and thunderstorm activity,
becoming more widespread through the day. The most favorable
region for widespread and potentially heavy rain will be along and
northwest of a line from Apalachicola through Tifton. On Monday,
drier air will move in aloft, with deep layer ridging taking hold
in the wake of the northern stream trough and TUTT. Expect a more
typical scattering of summertime seabreeze convection Monday.
.LONG TERM [Monday Night Through Saturday]...
The shortwave in the Middle Mississippi Valley will start the
anomalous amplification of the northern stream longwave trough,
with a couple more shortwaves superpositioning over the eastern
CONUS through the week. Tuesday's convection will likely still be
seabreeze driven, though mid to late week storms should be more
widespread associated with the northern stream trough and
associated cold front. It's unlikely we'll get a 'clean' frontal
passage, so wet conditions should be expected as the front will
likely stall and dissipate over the Southeast.
.AVIATION [Through 12Z Sunday]...
Brief period of MVFR cigs/vsbys at DHN and VLD this morning.
Otherwise, showers and thunderstorms currently developing along
the panhandle coast and inland near ECP this morning will
gradually spread north and east through the day. Expect at least
brief impacts from storms with gusty winds and possible MVFR
Seasonably low winds and seas are expected over the next several
days, but could increase as we near mid-week as a cold front
Outside of possible low dispersions across portions of the Florida
panhandle Sunday afternoon, hazardous fire weather conditions are
In general, 1-2" of rain is forecast along and west of the
Apalachicola and Chattahoochee rivers over the next couple of days
and around 1" to the east. Isolated higher amounts are possible
especially through the weekend. Ensemble guidance for area rivers
suggests the potential for action stage along the most reactive
basins west of the aforementioned delineation. Scattered 'nuisance'
urban and rural flooding will also be possible through the next
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 90 74 89 73 90 / 50 20 40 10 40
Panama City 88 78 86 77 88 / 70 40 60 40 40
Dothan 87 73 86 73 88 / 70 30 60 30 40
Albany 88 73 88 73 90 / 60 30 60 20 30
Valdosta 90 73 89 72 91 / 40 20 40 10 30
Cross City 91 75 90 74 91 / 30 20 20 20 30
Apalachicola 88 78 87 77 87 / 40 30 50 20 30
FXUS62 KMFL 181354
Area Forecast Discussion
National Weather Service Miami FL
954 AM EDT Sat Aug 18 2018
Isolated Atlantic showers are spreading toward the coast and will
increase in coverage this afternoon as sea breeze spreads inland.
Guidance is not overly enthused with convection anywhere but
western interior, and 12z RAOB analysis doesn't appear to reveal
air mass too favorable for intense convection. Thus, considering
that Gulf/Atlantic sea breezes in easterly flow regime should
collide over western interior, have maintained high POPs and
potential for strong downburst winds in this area. Otherwise,
expect near normal temperatures reaching around 90 degrees for
Fort Lauderdale's low temperature yesterday /August 17/ was only
83 degrees, which tied the daily record warm minimum, last set in
2013. Rainfall this morning cooled Fort Lauderdale such that no
records were threatened today.
.PREV DISCUSSION... /issued 831 AM EDT Sat Aug 18 2018/
Guidance suggests most activity will develop over or just inland
of east coast terminals midday and then spread westward, thus
will maintain only VCSH this afternoon, not VCTS. Better chance
will occur at KAPF where Gulf sea-breeze intrusion will be impeded
by easterly flow. Expect ESE flow 10 KT during the day and
East/southeast onshore flow will create a moderate risk of rip
currents on Atlantic beaches today.
PREV DISCUSSION... /issued 421 AM EDT Sat Aug 18 2018/
Latest water vapor imagery loop indicates an area of dry air in
the mid and upper levels stretching from Central Florida eastward
towards Bermuda. This dry/sinking air is associated with a rather
strong 594 mb high pressure cell. Clockwise motion around this
feature has allowed for persistent easterly flow to southern
Florida overnight. A distinct tongue of moisture can be observed
on satellite derived PWAT stretching from the northern Keys
eastward toward the Bahamas with values greater than 2.0". As
this area of enhanced moisture slowly edges towards our CWA, the
threat of precipitation will steadily increase. The GFS progs a
rather compact vort max to develop this afternoon near the
Straights and move over the Everglades. As this feature
approaches, 500 mb temps drop to -8 or -9 C. Deeper moisture and
greater instability, compared to the last several days, should
bring a greater coverage of mainly afternoon and evening
thunderstorms. Some of the storms could become strong, producing
downdraft winds in excess of 45 mph. Small hail will also be
possible due to the colder than normal air aloft, especially over
the western interior and southern portions of Miami-Dade County.
Maximum temperatures are forecast in the upper 80s to near 90
along the coasts with low 90s forecast elsewhere. These values are
a degree or two below normal for this time of year.
Late this weekend through mid next week the synoptic pattern does
not budge much. High pressure over the western Atlantic will
continue to bring easterly or southeasterly flow into South
Florida, driving deep moisture and instability over the area.
Similar to previous days, there will be an elevated threat of
mainly afternoon/evening convection over the interior and Gulf
Coast. Showers and thunderstorms will also be possible along the
east coast metro region, but definitely more isolated.
Temperatures each afternoon should reach near 90 degrees along the
coast and low 90s for the interior.
High pressure across the western Atlantic will
prevail through early next week. Moderate east to southeasterly
flow will continue across the local waters with favorable boating
conditions. Scattered showers and thunderstorms are possible
each day. Winds and waves could be higher in and around any
shower or thunderstorm.
Convection continues pushing ashore from the Atlantic this
morning. Expect mostly VFR with brief bouts of sub-VFR. Additional
convection possible through the morning into the afternoon with
the highest storm coverage expected to the interior of the
terminals. APF should see a diurnal sea breeze pattern with the
threat of storms again as well. Short-fused amendments will likely
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 89 78 89 78 / 30 30 40 20
Fort Lauderdale 89 80 89 81 / 20 30 40 20
Miami 89 78 89 79 / 20 30 40 30
Naples 90 76 90 77 / 50 20 30 10