Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Jacksonville Florida
213 PM EDT Thursday Apr 17 2014
..heavy rainfall and flooding possible Friday and Friday night...
Short term /through Friday night/...
isolated/widely scattered showers across the coastal waters are
approaching mainly the southeast Georgia coast...with an isolated shower or two
making it onshore. Will include isolated coastal showers late afternoon
into the evening. The thick canopy of low clouds that has plagued
the area much of the day is showing signs of thinning out some.
Will use mostly cloudy skies for late this afternoon/evening with clouds
increasing overnight. The initial shortwave ahead of stacked low
pressure will approach the area from the west late. Given a slower
trend...will keep higher probability of precipitation out of the area tonight...with mainly
low/middle end scattered probability of precipitation by late in the overnight. Seasonably
mild lows in the middle/upper 50s far inland with 60 to 65 closer to
the coast will prevail.
Friday/Friday night...the 12z GFS/00z European model (ecmwf) continue to be in decent
agreement...with the 12z NAM still further south with the nearly
vertically stacked low. However...the NAM is trending somewhat
closer to the GFS/ECMWF. Will generally use a GFS/European model (ecmwf) blend
with precipitation increasing substantially west to east Friday morning
with categorical probability of precipitation for all areas by later Friday afternoon and
into Friday night. Precipitation will begin to decrease slowly by later
Friday night as the upper low is prognosticated to enter southeast Georgia with
the greatest lift/moisture exiting into South Carolina. A deep
moisture tap with precipitation water values around 2 inches will
enter the region Friday...lingering through Friday night. Areal
average rainfall totals of 2 to 4 inches will be possible
through Friday night. With the rather wet antecedent soil
moisture conditions...especially across portions of southeast Georgia into
NE Florida...will issue a Flood Watch for all areas for Friday afternoon
through Friday night. With the track blend of the GFS/ECMWF...think
the strong/severe thunderstorm will remain to the south of the area.
Will include isolated thunderstorms for NE and north-central Florida Friday
aftn/night. Breezy to windy conditions will be likely once again
Friday afternoon into Friday evening. With clouds/precip...high
temperatures Friday across southeast Georgia will held down into the
60s...with milder Lower/Middle 70s foe NE Florida. Lows Friday night will
be similar to tonight.
Long term /Saturday through Thursday/...
models still have timing and location differences with the low
pressure system but have enough similarities to conclude that on
Saturday the upper level cutoff low and surface low will phase
together over our region. Significant wrap-around moisture is
expected linger into the afternoon with the bulk of the moisture
over southeast Georgia...as the system slowly moves offshore. Heavy rainfall
may persist early Sat morning for some areas but overall rainfall
amounts will be lighter as rain chances decrease. Between the rain
and abundant cloudiness will keep highs in the 60s for most of the
region...but more sun over the southern zones will allow temperatures to reach
the lower 70s. Rainfall is expected to end from SW to NE Sat
night...but wrap-around moisture could linger into early sun for
coastal sections. Lows Sat night will fall into the 50s inland to
near 60 at the coast.
Stacked cyclone slowly moves into the western Atlantic waters
on Sat night/sun...maintaining a cool northerly flow over our
region. Despite decreasing clouds from west to east...highs inland
climb into the low/middle 70s...but coastal locations may struggle
to reach upper 60s. Next shortwave trough will slide into our
region late Tuesday and associated frontal boundary is expected to have
limited precipitation. Shortwave ridging will then prevail middle week...with
highs rebounding into the Lower/Middle 80s Wed/thur. Weak disturbances
in the upper flow across Georgia may produce low end probability of precipitation middle week.
prevailing MVFR ceilings is forecast through Friday. IFR ceilings are
possible overnight...but confidence is low at this time. Strong
NE winds will continue at 15-20g25kt...then decrease below 12 knots
around 01z at the terminals except at ssi. Rain chances increase
with vcsh beginning 08z. More steady rain arriving between
13z-14z Friday morning.
strong NE flow event will continue into the weekend...with Small Craft Advisory
through Friday for all legs...and for the offshore legs into
early next week as seas will remain elevated. Conditions will
improve early next week as high pressure builds over the region.
Rip currents/surf: high risk through Friday with strong onshore
flow. Surf heights 4 to 6 feet.
Preliminary point temps/pops...
amg 54 62 54 67 / 40 100 100 50
ssi 60 64 60 66 / 30 100 100 60
jax 61 73 60 67 / 30 100 90 50
sgj 64 73 63 69 / 30 100 90 50
gnv 61 76 60 70 / 40 100 90 40
ocf 63 78 62 72 / 40 90 80 40
Florida...Flood Watch from Friday afternoon through late Friday night for
High rip current risk through Friday evening for Duval-Flagler-
Lake Wind Advisory until 7 PM EDT this evening for Duval-Flagler-
Georgia...Flood Watch from Friday afternoon through late Friday night for
Camden-coastal Glynn-Coffee-Echols-inland Camden-inland
High rip current risk through Friday evening for coastal Camden-
Lake Wind Advisory until 7 PM EDT this evening for coastal
Am...Small Craft Advisory until 6 PM EDT Monday for Altamaha Sound Georgia
to Fernandina Beach Florida 20 nm to 60 nm offshore-Fernandina
Beach to St Augustine Florida 20 nm to 60 nm offshore-St
Augustine to Flagler Beach Florida 20 nm to 60 nm offshore.
Small Craft Advisory until 6 PM EDT Friday for Altamaha Sound Georgia
to Fernandina Beach Florida out 20 nm-Fernandina Beach to St
Augustine Florida out 20 nm-St Augustine to Flagler Beach Florida out