Area forecast discussion...update to aviation
National Weather Service Mobile Alabama
1230 PM CDT Monday may 20 2013
Aviation...(18z issuance)...vcr ceilings/visbys expected today through
the evening. Strong onshore flow over the lower miss River Valley is
expected to bring IFR level ceilings to mainly western areas of the forecast area.
Areas east of the stratus influx are expected to see visbys drop to
IFR or lower levels due to radiational cooling. Where this
transition occurs is flexible at this time...but is expected to be roughly
along the miss/Alabama state line.
/16
&&
Short term (today and tonight)...in a persistent warm and moist
southerly flow...satellite data shows low clouds over the southern
states. These clouds are forecast to mix out this morning. A middle
level ridge of high pressure will be in place today and unlike
yesterday...expect more of a sunny day which allows for good
insolation and warming. Considering more sun...the building ridge
aloft and high resolution forecast soundings showing a large spread
occurring in the boundary layer temperature/dewpoint profiles
resulting in dry conditions...the environment favors high
temperatures lifting into the upper half of the 80s to lower 90s
over the interior. Southerly flow off the cooler Gulf waters keep
beach temperatures modified into the lower 80s there. Surface
dewpoints in the middle to upper 60s make for a warm and muggy night
with potential of patchy late night fog formation. Given current
trends we see in low temperatures...the forecast highs for today and
the persistent pattern that remains in place...will trend higher
than the MOS for overnight lows. /10
A preliminary look at this afternoon's wet microburst risk is
low.
&&
Long term (tuesday through sunday)...the upper ridge will persist
across the area through Tuesday. Forecast soundings show precipitable
waters generally in the 1-1.25 inch range with enough dry air in the
850-700 mb layer to result in dewpoints mixing out some. This will
limit afternoon instability...and when combined with the subsidence
of the ridge...a dry day is expected with highs again in upper 80s to
lower 90s inland with low to middle 80s along the coast.
The ridge breaks down and shifts east on Wednesday as a trough moves
east out of the plains into the Midwest and lower MS valley. An
organized area of convection will likely be ongoing across the
midsouth south into the arklatex early Wednesday morning...with the
convection gradually moving east through the day. This will support
higher rain chances by afternoon west of I-65...especially over
inland southeast Mississippi. There is some uncertainty on far how
east the convection will persist...given the potential of dewpoints
once again mixing out over the eastern zones due to the residual
ridging and dry air aloft. Will keep probability of precipitation in the slight chance range
for now across the eastern zones. By Thursday...a shortwave is
forecast to amplify over the Ohio Valley with the base of the trough
extending into the southeast states. A weak surface trough developing
inland combined with the afternoon seabreeze will support the
development of scattered showers and thunderstorms across the region.
A few strong pulse storms with small hail and gusty winds are
possible...with MLCAPES forecast to reach near 2000 j/kg and
middle level lapse rates of 6.5-7.0 c/km.
The aforementioned shortwave continues southeast into the Carolinas
on Friday with a cold front moving into the inland County Warning Area during the day
and pushing offshore Friday night. Deep layer moisture quickly gets
scoured out during the day Friday...so will confine slight chance
probability of precipitation to the coastal zones...but it very well could remain dry across
all areas. A dry weekend is expected with seasonably warm temperatures but
lower humidity values. 34/jfb
&&
Marine...westward extension of western Atlantic surface high...to
across the Gulf...maintains light onshore winds through
midweek...possibly a little stronger near the coast...over bays and
sounds in the afternoon hours due to daily and northward advancing
coastal sea breeze. Rainfree weather forecast today and Tuesday with
a bit more of chance of showers/storms near shore Wednesday and
Thursday as base of upper level trough pivots eastward across the
central Gulf Coast. By the close of the week...the extended range
weather models bring a frontal passage and an offshore component to
the wind to the coastal waters on Friday. Seas to change little this
week...ranging 1 to 2 feet. /10
&&
Preliminary point temps/pops...
Mobile 87 68 87 67 86 / 05 05 05 05 30
Pensacola 87 70 87 70 85 / 05 05 05 05 20
Destin 82 71 83 72 81 / 05 05 10 05 20
Evergreen 91 65 92 66 90 / 05 05 10 10 30
Waynesboro 90 65 90 66 86 / 05 05 10 10 40
Camden 91 65 91 66 88 / 05 05 10 05 30
Crestview 91 64 92 66 90 / 05 05 10 05 20
&&
Mob watches/warnings/advisories...
Alabama...none.
Florida...none.
MS...none.
GM...none.
&&
$$
