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Area Forecast Discussion (AFD)

Issued by Jacksonville, FL (JAX)

FXUS62 KJAX 140830

Area Forecast Discussion
National Weather Service Jacksonville FL
430 AM EDT Sat Sep 14 2019


.NEAR TERM.../Today-Tonight/...
Persistent and increasing northeast low level flow and increased
moisture will continue through tonight as T.S. Humberto located 
over the northwest Bahamas drifts to the northwest today-tonight.
The NHC takes the cyclone northwest and then north-northwest 
through Sunday. For Today, expecting a breezy/windy day with a 
chance of showers and potential thunderstorms as low level 
convergence and daytime heating generate convection. Somewhat 
limited area of stronger winds for coastal counties leads to lower
confidence on raising a wind advisory for the coast through 
tonight but will be monitored today. 

Best rain chances will along the northeast FL and southeast GA 
coastal counties through tonight...with POPs ranging from 30-60 
percent at this time. Based on the low level wind field (sfc-3km)
being northeast at 20-25 mph, a few showers and potential storms 
will be able to push well inland to I-75 and parts of southeast GA
which should fade during this evening. An area of moisture over 
far northwest southeast GA zones will also support a few showers 
and storms generally north of Waycross. Temps today expected near 
90 inland and mid 80s at the coast. Winds should relax tonight for
inland areas but coastal areas will still experience northeast 
winds around the 15-25 mph range.


Confidence continues to increase that Tropical Storm Humberto will
remain offshore and the main local impacts we'll see will be 
breezy conditions and rough surf. Humberto is expected to move 
roughly parallel to the coastline as it heads northward Sunday, 
then making a right turn Sunday night. With our area sandwiched 
between a ridge of high pressure and Humberto, the pressure 
gradient will be tight- making for windy conditions through 
Monday, particularly along the immediate coastline. There's still 
a chance for low-end tropical storm (around 40 mph) winds or wind 
gusts Sunday and Monday along the coastline, although the trend 
has been for these chances to decrease. Scattered to widespread 
showers and isolated thunderstorms are expected through Monday as 
well, with the highest coverage near the coast. On the bright 
side, increased chances for storms and increased cloud coverage 
will lead to cooler temperatures- highs mostly in the mid-upper 
80s and lows in the low 70s. Temperatures will climb right back up
as ridging begins to build eastward, however, possibly rising 
into the mid-90s on Tuesday.


The low level ridge will continue to build eastward through the 
weekend, keeping low level flow from the east for the rest of the
week. At the upper levels, the area will remain east of the upper
level ridge, with a weak PV anomaly moving into the southeastern 
U.S. Friday-Saturday. Given the lack of large scale forcing, the 
area will remain mostly dry, with PoPs staying in the 20-40% range
to account for late-season seabreeze. Highs will mostly be in the
upper 80s-low 90s, and lows mostly in the upper 60s-low 70s.


Sct-broken low level clouds will persist today with ocnl MVFR 
especially for coastal TAFs as moisture pushes in off the Atlantic
waters. Increasing chances for showers during the day with a few 
storms possible at times. Best chance of showers will be for SGJ 
and CRG. Winds prevail from the northeast at 10-15 kt early today 
and will increase to 15-20 kt and gusty during the day and into 
late evening. Generally lower wind speeds at GNV today and 


Solid SCA conditions will persistent between the high pressure to
the north and TC Humberto to the southeast of the area. Winds and
seas will gradually build through Sunday while backing a bit to 
the north-northeast. Local mariners should monitor the latest 
official forecasts from the National Hurricane Center.

Coastal Impacts: Minor coastal flooding possible this weekend at
the east coast beaches and along the St. Johns River due to high 
astronomical tides and increasing onshore winds. Latest tidal

Rip Currents: High risk of rip currents through the weekend due 
to persistent onshore winds and rough surf. Will hold off on high
surf advy at this time based on latest guidance.



As Tropical Storm Humberto slides northward roughly parallel to the 
Atlantic coastline, strong east-northeasterly winds are expected today 
and strong northeasterly winds tomorrow. These high winds, coupled with
low mixing heights will spike dispersion indices today and tomorrow. 
Aside from the winds, no hazardous fire weather conditions are expected 
as humid conditions and chances for showers will continue for the next
few days. Isolated thunderstorms are possible. 


AMG  90  73  88  71 /  30   0  30  10 
SSI  87  77  85  76 /  20  50  60  50 
JAX  88  76  86  74 /  40  50  60  40 
SGJ  86  77  85  75 /  50  60  60  40 
GNV  89  75  87  72 /  30  20  50  10 
OCF  90  75  88  73 /  30  20  50  10 


FL...High Rip Current Risk through Sunday evening for Coastal Duval-
     Coastal Flagler-Coastal Nassau-Coastal St. Johns.

GA...High Rip Current Risk through Sunday evening for Coastal Camden-
     Coastal Glynn.

AM...Small Craft Advisory until 10 PM EDT Monday 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 8 PM EDT Sunday for Coastal waters 
     from Fernandina Beach to St. Augustine FL out 20 NM-Coastal 
     waters from St. Augustine to Flagler Beach FL out 20 NM.

     Small Craft Advisory from 8 AM this morning to 8 PM EDT Sunday 
     for Coastal waters from Altamaha Sound to Fernandina Beach 
     FL out 20 NM.