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Area forecast discussion 
National Weather Service Jacksonville Florida
432 PM EDT Tuesday Sep 16 2014

..locally heavy downpours expected through this evening...

..Ocean swells from distant Hurricane Edouard to increase the
threat for rip currents on Wednesday and Thursday...

Currently...
afternoon surface analysis depicts a surface trough positioned
along the Interstate 10 corridor in northeast Florida...with a cold
front pushing southward into the western Carolinas and northern
Georgia/Alabama. Aloft...deep-layered troughing is digging into
the eastern United States...with ridging retrograding towards the
central and southern Gulf of Mexico. Convection earlier today
ahead of the surface trough over north central Florida is waning in
coverage...while scattered showers and thunderstorms are
developing well ahead of the cold front over the Suwannee Valley
and near the Altamaha river. Clouds and rainfall are keeping
temperatures in the upper 70 to middle 80s...except upper 80s in
interior southeast Georgia where breaks in the clouds have
developed ahead of the cold front.

Short term...
hi-resolution models depict increasing coverage of convection
area-wide through the early evening hours. Used likely to
categorical probability of precipitation through the late evening hours...with heavy
downpours over saturated ground conditions being the primary
threat. A few strong thunderstorms are possible where some more
instability exists over interior southeast Georgia...with brief
downdraft wind gusts and frequent lighting strikes being the
primary threats in these locations. Convection will then gradually
decrease in coverage and shift southward into northeast and
north central Florida during the overnight hours...where scattered
coverage was used in the forecast grids through sunrise. Skies
will begin to clear over interior southeast Georgia during the
predawn hours...where areas of fog are expected to form as a moist
air mass persists in the low levels. Lows will fall to the low to
middle 70s region-wide.

Wednesday & Wednesday night...broad low pressure will trek east of the local
coast trailing a couple of wake troughs over the local forecast
area. Wednesday morning showers and isolated thunderstorms will be most probable
offshore and south of a sgj-gnv line...with a few showers to the
north. As midday approaches...widespread heavy rain will track
east of the local waters as the surface low departs...but do expect an
increase in scattered showers and isolated tstorm along the
Atlantic coast and Gulf Coast with daytime heating and increased
forcing from a passing upper level short wave trough from the northwest.
Advertised rain chances of 20-30% over southeast Georgia and 30-50% over NE Florida
where deeper moisture and stronger low level convergence will
coincide in the aftn/evening. Temperatures will warm to near 90 over
inland southeast Georgia and the northern Suwannee River valley...with middle to
upper 80s elsewhere. Precipitation will push offshore of the coast by
midnight...with clearing and drying over night Wednesday. Patchy fog
will be possible well inland as temperatures cool into the upper 60s to
low 70s.

Thursday & Thursday night...mostly dry and cooler with mean layer northerly
flow in place as troughing shifts over South Florida and high pressure
builds over the middle-Atlantic region. As onshore develops in the
afternoon...there will be a low chance of coastal showers...but
capped rain chances at 20% for now. Temperatures will range in the
middle/upper 80s. Low chances of coastal showers will continue Thursday
night...with min temperatures ranging from the middle 60s inland to low 70s
river basin/coast. Patchy late night fog possible inland.

Long term (friday through tuesday)...
Friday & Sat...a high pressure wedge will nose southward over central
Georgia with an inverted trough offshore of the southeast Atlantic coast. This
regime will bring breezy onshore flow to the coast with waves of
showers and isolated thunderstorms. Precipitation will edge inland through the
day Friday with an increase in coverage and intensity as an upper
level trough passes overhead. Rain chances range from 30-40%
coast to 20-30% inland. Temperatures will be notably cooler with highs in
the low/middle 80s and mins in the middle/upper 60s inland to low 70s
river basin/coast. Could see some late night fog development well
inland each night.

Sun through Tuesday...mean layer troughing will impact the eastern
Seaboard early next week which will bring a gradual increase in
diurnal shower and tstorm activity each day as another surface
front edges southward over Georgia. Rain chances at this time range
from 20-30%. Temperatures will moderate near to above climatology values with
highs in the middle/upper 80s and mins in the upper 60s/middle 70s
coast.

&&

Aviation...
most sites will continue to be impacted with visible and/or ceiling
restrictions due to thunderstorms and rain for the next few hours. Another round of
thunderstorms and rain could develop and impact crg...jax...and ssi through sunset.

&&

Marine...
numerous showers and thunderstorms are expected tonight as a cold
front pushes into our region. This front will push south of the
coastal waters by Wednesday evening. Long period swells from
distant Hurricane Edouard will reach the offshore waters
overnight...with seas building to 3-5 feet overnight. Small craft
advisories will be required for the offshore waters on Wednesday
and Wednesday night...where swells of 5 to 7 feet are expected.
Swells of 3-5 feet are expected in the near shore waters. Swells
offshore will subside to 4-6 feet on Thursday and down to 3-5 feet
on Thursday night. High pressure will build over New England on
Friday...expanding southward and tightening our local pressure
gradient. Northeast winds will increase to caution level speeds on
Friday offshore...with caution conditions possible on Friday night
and Saturday in the near shore waters. Onshore winds and seas will
then subside on Sunday.

Rip currents: low risk through tonight. Long period easterly
swells will begin reaching our offshore waters after
midnight...with wave-watch indicating 12 to 15 second periods
impacting our waters from Wednesday afternoon through Thursday. A
high risk of rip currents is expected tomorrow and Thursday...with
an elevated risk continuing into the upcoming weekend as onshore
winds increase.

&&

Preliminary point temps/pops...
amg 71 90 68 86 / 60 20 20 10
ssi 74 85 72 83 / 70 20 30 20
jax 71 88 71 87 / 80 30 30 10
sgj 72 84 72 85 / 80 40 40 20
gnv 70 88 69 88 / 80 50 30 10
ocf 71 88 70 89 / 80 50 40 10

&&

Jax watches/warnings/advisories...
Florida...none.
Georgia...none.
Am...none.
&&

$$

Nelson/enyedi/sandrik/Walsh

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