Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Mobile Alabama
429 am CDT Friday Jul 11 2014

Short term (today and tonight)...a positively tilted upper trough over
the eastern states weakens and moves off to the east with upper
ridging over the plains building into the region. Modest subsidence
associated with the ridging mainly affects the interior western
portion of the area while the exiting upper trough brings somewhat
drier air into the northern portion of the area. This results in
precipitable water values dropping to 1.5-1.75 inches over the
interior portion but otherwise remaining near 2.0-2.2 inches over the
remaining area. Convection yesterday developed upstream of the area
and progressed southeastward along an 850 mb Theta-E ridge/surface
trough and into the forecast area with additional development on old
boundaries/sea breeze. A similar surface trough and 850 mb Theta-E
pattern will be present today albeit somewhat weaker given the
changing upper pattern and also shifted southward such that
convection that develops upstream will mainly affect areas west of
the forecast area but should also include portions of extreme
southeast Mississippi and possibly extreme southwest Alabama. A
surface ridge over the northern Gulf maintains a synoptic scale
southerly flow...and expect additional convective development mainly
over the southern half of the area along the sea breeze and surface
boundaries left over from previous convection. Have gone with slight
chance to chance probability of precipitation for the interior area with good chance probability of precipitation
closer to the coast where better deep layer moisture will be...and
included likely probability of precipitation for a portion of the northwest Florida Panhandle
where best deep layer moisture is present. Slight chance probability of precipitation follow
for the evening hours for lingering convection. A few strong storms
are possible with small hail and strong wind gusts. Highs will be
near to slightly above seasonable levels with near seasonable lows.
/29

This afternoon's wet microburst risk is moderate.

(Saturday through sunday)...we noted the GFS prognostic charts show
a positively tilted wave pattern. A 500 mb ridge with a closed
geopotential height of 5940 M remains anchored over the Ozarks region
ridging over the Central Plains into the southwest states Saturday.
The alignment of this feature with a deep wavenumber 5 trough to its
north and much shorter wave off the Atlantic coast will bring a
northeast flow aloft over our region on its eastern fringe. The
ingredients for convection will be here most afternoons...convective available potential energy above
1500 and often over 2000 j/kg and lifted index generally around -4
with precipitable water above 1.5 to 1.75 inches. Cloud cover will
generally begin as none around sunrise quickly becoming scattered
around middle morning...allowing the heating to destabilize the column
allowing convection to get started.

Highest probability of rain Saturday will be in the eastern portions
of the region near the coast...but Sunday and most of early next
week it will be more in line with The Reach of the seabreeze.
Isolated to scattered convection focused offshore overnight. Hot and
humid with afternoon highs from the middle 80s to around 90 near the
coast to the lower to middle 90s inland. Lows will be near seasonal from
around 70 inland to the lower to middle 70s near the coast. Heat index
around 101 to 102 so won't mention it in the zone products just yet.
/77

Long term [sunday night through thursday]...not much change to the
extended. The GFS and Euro surface features are remarkably close
phased from initialization out to 144 hour. After forecast hour 144...things get
a bit more scrambled. Nonetheless we are pretty confident in the
forecast at least until Wednesday...and after that it is a
wait-and-see situation. With all due respect to what is happening
with a cooling trend mentioned in the northern United States...our
Ozark area ridge would deflect the cooler air from our region keeping
it north and US in the 90s during our middle weekdays through Thursday.
However even with that ridge being in place...our area could see the
passage of middle level impulses on its periphery and with precipitable
water values close to climatology... we think it wise to maintain
isolated to scattered convective rainfall through late in the week
with coverage most focused near the seabreeze. After all the eastern
edge of that upper ridge shows signs it will break down next week as
lower heights dig into the southeast. If that happens the temperature
could show a slight dip and chances of showers/storms would continue.
But for now...highs in the middle 90s most of the area...except for the
coast...upper 80s and lower 90s. Little change in overnight
lows...lower 70s interior to middle/upper 70s coast. /77

&&

Aviation (12z issuance)...VFR conditions prevail through the period
except for possible light fog in the early morning and will have a
tempo group from 18-22z at the taf sites for MVFR conditions in
thunderstorms. /29

&&

Marine...a ridge of high pressure over the northern Gulf will
maintain a mainly light southwesterly flow through Tuesday. Wind
and seas will be higher in and around isolated to scattered
thunderstorms. /29

&&

Preliminary point temps/pops...
Mobile 93 72 92 73 94 / 40 20 30 20 30
Pensacola 92 76 90 77 93 / 40 20 30 20 30
Destin 90 76 86 78 91 / 50 20 30 20 30
Evergreen 93 70 92 70 96 / 30 10 30 20 20
Waynesboro 94 69 95 69 94 / 20 10 20 10 20
Camden 93 71 94 72 96 / 20 10 20 20 20
Crestview 92 70 92 71 96 / 50 20 30 20 30

&&

Mob watches/warnings/advisories...
Alabama...none.
Florida...none.
MS...none.
GM...none.
&&

$$

National Weather Service Glossary of Abbreviations