Area Forecast Discussion
Issued by NWS Jacksonville, FL
FXUS62 KJAX 211936
Area Forecast Discussion
National Weather Service Jacksonville FL
336 PM EDT Fri Oct 21 2016
...Much Cooler Temperatures Tonight through the Weekend...
.Near Term /Through Saturday/...
Visible satellite and observations show a strong cold front was
moving into northeast Florida early this afternoon. Warm
temperatures were observed across the region ahead of the front
this afternoon, generally in the low to mid 80s. The front will
continue to push quickly to the southeast this afternoon, with
much drier and cooler air filtering into the region through
Saturday. Temperatures will fall 30-35 degrees from todays highs
into the mid 40s to mid 50s. Northwesterly winds will remain 5-10
mph overnight, so it will feel a few degrees cooler than the low
temperature as well. Cold air advection will continue through
Saturday, and temperatures will struggle to get into the lower
.Short Term /Saturday Night through Monday Night/...
Surface ridging will build over our region from the northwest this
weekend and will weaken overhead on Monday afternoon as a backdoor
cold front approaches our region from the north and northeast.
Cold air advection will continue on Saturday night, with
northwesterly winds of 5-10 mph persisting through the late
evening hours before gradually diminishing during the predawn
hours. Clear skies and diminishing winds late will make Sunday
morning the coolest of this stretch, with inland lows dropping to
the low to mid 40s, ranging to the lower 50s at the beaches.
Light winds can be expected area-wide on Sunday, except for a
slight increase in onshore winds at coastal locations during the
afternoon. Otherwise, full sunshine will prevail, which will boost
highs back up to near climo at inland locations, where mid to
upper 70s are expected. Coastal highs on Sunday will likely remain
in the lower 70s as shelf waters cool and winds become onshore
during the afternoon hours.
High clouds may increase during the overnight hours through Monday
morning as a shortwave tracks eastward through the Ohio Valley.
Otherwise, expect radiational cooling during the evening hours to
result in a rapid drop in temperatures, with lows inland falling
into the mid 40s, ranging to the mid 50s at the beaches. Heights
aloft will rise on Monday, with a very dry low level air mass and
filtered sunshine boosting inland highs to the low or mid 80s.
Onshore winds developing during the afternoon hours will keep
highs at the beaches in the upper 70s. The backdoor frontal
boundary will slide through southeast Georgia during the overnight
hours on Monday night, reaching the I-10 corridor towards sunrise.
No rainfall and little in the way of cloudiness is expected along
and ahead of the front. Lows will fall to the low to mid 50s
inland, ranging to the low/mid 60s at the beaches.
.Long Term /Tuesday through Friday/...
Strong surface ridging will build eastward from the Great Lakes
States on Tuesday morning to New England by Wednesday night. This
feature will drive the backdoor cold front through the rest of
northeast and north central Florida on Tuesday morning. Onshore
winds will strengthen in the wake of this front on Tuesday
afternoon, with breezy conditions expected for locations along and
east of the St. Johns River and I-95 in southeast Georgia. A
coastal trough will develop by Tuesday night as our local pressure
gradient continues to tighten, with convergent flow developing
showers over the coastal waters that may advect inland as far west
as I-95 by the predawn hours on Wednesday. Lows Tuesday night will
range from the mid/upper 50s over inland southeast Georgia and the
western Suwannee Valley to the mid/upper 60s at the coast. Overall
moisture levels will remain low on Wednesday and Wednesday night,
with coastal shower chances being confined to locations south of
St. Augustine. Breezy easterly winds will prevail in the coastal
counties on Wednesday and Wednesday night, with highs ranging
from the lower 80s for inland north central Florida to the
mid/upper 70s at the coast. Lows Wednesday night will range from
the upper 50s over inland southeast Georgia and the western
Suwannee Valley to the upper 60s at the coast.
A shortwave trough diving southeastward from Canada on Wednesday
will amplify over the Great Lakes states and Ohio/Tennessee
Valleys by late Thursday. This weather pattern may allow coastal
troughing to move onshore, which would result in at least
isolated to widely scattered showers for eastern sections on
Thursday and Thursday night. Southeasterly flow may increase
low level moisture values enough for more coverage than what long
term model blends are currently indicating. Increased cloudiness
and onshore winds will keep highs on Thursday in the mid/upper 70s
along the coast, ranging to the lower 80s for north central
Florida. Lows Thursday night will again range from the upper 50s
well inland to the upper 60s at the coast. A drier air mass is
then expected to filter into our region for the end of the week as
shortwave energy migrates offshore and becomes replaced by weak
ridging. Highs on Friday are expected to range from the lower 80s
inland to the upper 70s at the coast.
VFR conditions will prevail through the period. Northwest winds
10-15 knots will prevail this afternoon with higher gusts. Winds
will diminish to 5-10 knots overnight and then continue through
the period with clear skies.
Cold front moving across the regional waters this afternoon. Winds
will quickly pick up by this evening to 20-25 knots, and a few
gusts to gale force are possible well offshore tonight. Small
Craft Advisories are in effect for the nearshore waters through
Saturday morning and the offshore waters through Saturday
afternoon. Winds will diminish to 15-20 knots Saturday morning and
then to 10-15 knots by Saturday afternoon as high pressure builds
into the region. General north to northwest flow should remain
below headline levels Sunday and Monday before next east northeast
onshore surge begins late Tuesday and continues much of next
Rip Currents: Moderate risk through Saturday morning then becoming
low through early next week.
High dispersion values are expected region-wide through sunset as
northwesterly transport and surface winds strengthen, with surface
wind speeds of 15-25 mph and gusts up to 30 mph. A cooler and very
dry air mass will plunge into our area tonight, with long periods
of critically low relative humidity values expected at inland
locations each afternoon from Saturday through Monday. Surface
winds speeds will remain below 15 mph during this period and fuel
moisture values will remain too high to support red flag
conditions through Monday afternoon. Light wind speeds on Sunday
may result in low dispersion values at inland locations.
Coastal Flood Statement continues through tonight due to elevated
water levels. The offshore winds developing should help keep
levels below minor flood criteria.
.PRELIMINARY POINT TEMPS/POPS...
AMG 48 72 42 78 / 0 0 0 0
SSI 55 71 50 71 / 0 0 0 0
JAX 49 72 46 76 / 0 0 0 0
SGJ 55 72 52 72 / 0 0 0 0
GNV 48 74 43 78 / 0 0 0 0
OCF 49 74 44 77 / 0 0 0 0
AM...Small Craft Advisory until 6 PM EDT Saturday for Waters from
Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-
Waters from Fernandina Beach to St. Augustine FL from 20 to
60 NM-Waters from St. Augustine to Flagler Beach FL from 20
to 60 NM.
Small Craft Advisory until 10 AM EDT Saturday for Coastal waters
from Altamaha Sound to Fernandina Beach FL out 20 NM-
Coastal waters from Fernandina Beach to St. Augustine FL
out 20 NM-Coastal waters from St. Augustine to Flagler
Beach FL out 20 NM.