Area forecast discussion
National Weather Service Birmingham Alabama
632 am CDT Thursday may 23 2013
Update...
for 12z aviation.
&&
Short term...
today through Saturday.
Mainly rain free conditions are prevailing across central Alabama
early this morning....as a surface trough based on surface analysis
and water vapor imagery continues to push off to our east into
Georgia. An outflow boundary moving southeastward behind the
surface trough has been able to trigger a few showers across our
southeastern counties...but only isolated showers are expected
through sunrise. The front that slowly moved into our area yesterday has
pretty much washed out...with no wind shift or advection of drier
dewpoints evident at any observation location in the region.
Dewpoints are a bit drier across the Tennessee Valley
however...with lower 60s observed there as opposed to upper 60s
across far southern Alabama and the Florida Panhandle. VAD wind
profiles off kbmx are presenting a west southwesterly flow just
off the surface with northwesterly flow beginning at around 3k
feet. The west southwesterly flow near the surface is helping to
produce enough lift to develop some stratus...and where skies are
clear patchy radiation fog has been allowed to develop. With the
boundary layer winds staying around 15-20 kts we aren't expecting
any particularly dense fog to develop at this time...but we'll
monitor trends through the morning and keep only mention of patchy
fog in the forecast through sunrise for now...and mention
visibilities less than one mile at times in the severe weather potential statement for early this
morning.
For the forecast today...any low clouds and fog should dissipate
through middle-morning with very warm conditions expected this
afternoon. Relatively drier air will be able to move into the state
with a westerly to northwesterly surface flow developing which will
greatly limit any convective development. I've included a slight
chance of showers across our far southeastern counties for the first
few hours after sunset...but that should be about it in terms of
precipitation chances today. Low level thicknesses this afternoon are
supportive of middle to upper 80s areawide. The next upper shortwave
will quickly dive southeastward today from Missouri and
Illinois...and will send a punch of drier and cooler air in our
direction. The associated cold front should enter into northern
Alabama late this evening with a northerly wind shift expected for
the Interstate 20 corridor by midnight tonight. A few showers will
be possible as the shortwave moves across central Tennessee and the
Smoky Mountains where the most lift will be present...but the front
is expected to remain on the dry side for our area. The much cooler
and drier air will most certainly be noticeable during the day on
Friday with a nice northerly breeze and dewpoints dropping into the
upper 40s and lower 50s. Model guidance is advertising highs ranging
from the middle 70s across our northern counties to the lower 80s
across the south. Highs could be a degree or two higher than models
are indicating due to good insolation with the high sun angle this
time of the year...but middle 70s to lower 80s look to be on track.
Temperatures are looking to be quite chilly for some spots on
Saturday morning with sheltered valley locations perhaps reaching
the low to middle 40s. Temperatures look to slowly modify on Saturday
with gorgeous weather continuing and low to middle 80s expected for
highs.
Long term...
Sunday through Wednesday.
The long term forecast is generally unchanged from what was
mentioned in the discussion in the afternoon package
yesterday...with a fairly benign pattern possibly taking shape in
the form of an upper level ridge. That being said...the long range
suite of guidance is still trying to figure out how strong to
develop the upper ridge that will be in place across the Gulf Coast
states. The European model (ecmwf) remains the lone solution that tries to break down
the upper ridge faster and allow northwest flow aloft to send
several mesoscale convective systems in our direction Sunday through
Monday evening. The other guidance solutions maintain the strength
of the ridge and keep the disturbances well off to our north. For
now...I have left out mention of any probability of precipitation as we are still way too
far out to determine what will occur in the mesoscale. With the
majority of the guidance maintaining the upper ridge...temperatures
look to be on the warm side next week...with upper 80s to perhaps 90
degrees for highs once again on Tuesday and Wednesday.
56/gdg
&&
Aviation...
12z taf discussion.
Low clouds and patchy dense fog has finally set in across portions
of central Alabama this morning...with the worst impacts
across the north/west. Conditions will begin to improve by 13z and
should improve significantly by 14z. Otherwise...expect VFR
conditions to prevail through the remainder of the period. Winds will
generally be out of the northwest today at around 10 kts wit a few gusts
up to 20 kts possible. Look for light northwest winds overnight.
19
&&
Preliminary point temps/pops...
Gadsden 84 56 74 44 80 / 10 10 0 0 0
Anniston 84 58 76 47 80 / 10 10 0 0 0
Birmingham 85 60 77 50 82 / 10 10 0 0 0
Tuscaloosa 88 61 80 49 83 / 10 10 0 0 0
Calera 85 60 81 51 81 / 10 10 0 0 0
Auburn 86 60 78 53 81 / 20 10 0 0 0
Montgomery 89 63 84 52 85 / 20 10 0 0 0
Troy 88 61 83 50 83 / 20 10 0 0 0
&&
Bmx watches/warnings/advisories...
dense fog advisory until 9 am CDT this morning for the following
counties: Bibb...Blount...Calhoun...Cherokee...Clay...Cleburne...
Etowah...Fayette...Greene...Hale...Jefferson...Lamar...Marengo...
Marion...Perry...Pickens...Randolph...Shelby...St. Clair...
Sumter...Talladega...Tuscaloosa...Walker...Winston.
&&
$$
