Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mobile Alabama
441 am CDT Wednesday Jul 23 2014
Short term...(today through friday)...today through tonight...
middle/upper level low pressure noted by satellite this morning over
southeastern Louisiana...as expected. This feature is expected to
remain nearly stationary through today and into this evening...and
open into an elongated trough late tonight. Weakening surface boundary
continues over inland areas of the deep south with a high pressure
ridge persisting over the Gulf to the south. With this...the diurnal
convective pattern will continue but with the upper dynamics
weakening coverages are expected to be less. Expect best chances
today...around 40 percent...over western half of the forecast area where
influence of upper dynamics will still be strongest along with
effects of daytime heating. With loss of daytime heating this
evening...expect only isolated storms to remain during the evening
hours and then mainly over southern coastal counties and just inland.
No severe weather is anticipated...but as was the case yesterday...a
few storms could produce strong gusty winds...localized heavy
rainfall and frequent lightning. Also... with relatively cold pocket
of air aloft...could also see some small hail with the stronger
storms again today too. High temperatures across the region this afternoon
will range from the upper 80s to lower 90s...with the slightly cooler
temperatures over the western zones where cloud cover and precipitation chances will
be greatest. Low temperatures tonight in the upper 60s and lower 70s
interior counties and in the low to middle 70s coastal. 12/ds
Thursday through Friday...an upper system moving passing north of the
Great Lakes shifts the northern half of the upper trough over the
eastern Continental U.S. Farther east...whilst the tail end gets drawn west
around the base of an upper high situated over the Desert Southwest.
This also shifts an upper ridge stretching west over the Gulf of mex
back east a bit. A surface front gets pushed south across the
southeastern Continental U.S. And lower miss River Valley to near the
northwestern corner of the forecast area by Friday evening.
For the forecast...Thursday is shaping up to be the wettest day...with
probability of precipitation around seasonal. Temperatures around seasonal go with. The forecast area dries
out a bit for Thursday night into Friday as the stretching upper
trough over the lower miss River Valley and southeastern Continental U.S.
Weakens and shifts southeast of the forecast area. With the lessening
precipitation...temperatures rise a bit from Thursday...to a bit above seasonal.
Long term...(friday night on)...Friday night through Saturday...the
upper trough over the southeastern Continental U.S./Northern Gulf of mex
continues to weaken as the western upper high builds a Ridgeline east
over the Southern Plains and lower miss River Valley. Temperatures above
seasonal come with decreased chance of rain for the first part of the
weekend as a result.
Saturday night through Sunday night...another upper system moving
over the US/California builds...first squeezing the ridge over the lower miss
River Valley and southeastern Continental U.S. East a bit before the digging
trough over the eastern Continental U.S. Pushes it back west. The forecast area remains
under the influence of the upper ridge a bit longer...with temperatures
above seasonal and probability of precipitation below.
Monday through Wednesday...a pair of upper system moving through the
eastern trough help to push first push a weak surface front to just
south of the northern Gulf Coast Tuesday. How guidance handles the
second one varies...with the GFS pushing the boundary farther
south...and the European model (ecmwf) using the boundary for precipitation generation over
the Southern Plains and lower miss River Valley. Both are advertising
probability of precipitation around seasonal Sunday into Tuesday. The European model (ecmwf) maintains the near
seasonal chance of rain through middle week...especially over western
sections of the forecast area...whilst the GFS dries things out. Witht he better
chance of rain plus increased cloud cover from precipitation to the west of
the forecast area...the European model (ecmwf) drops temperatures below seasonal...whilst the drier GFS
maintains temperatures at or a bit above seasonal. The GFS ensembles are
advertising a solution in the middle...so have blended them for the
(23/12z issuance)...general VFR through much of the forecast
period...but occasional MVFR with ceilings around 3kft with reduced surface visibility
in and near scattered mainly afternoon showers and thunderstorms.
Marine...a weak and dissipating surface boundary just north and
inland from the coastal waters will move little and continue to
dissipate. Otherwise...a ridge of high pressure will remain in place
across the eastern Gulf of Mexico through the weekend. This pattern
will maintain a light to moderate southwest flow across the marine
area...with little change in seas (generally around 1-2 feet).
Isolated to scattered thunderstorms will be possible...especially
late night and early morning. 12/ds
Preliminary point temps/pops...
Mobile 88 71 90 73 91 / 40 20 40 20 30
Pensacola 89 74 89 76 90 / 20 20 30 20 20
Destin 88 76 88 76 88 / 20 20 40 10 20
Evergreen 91 69 91 70 92 / 30 20 50 20 30
Waynesboro 90 69 92 69 92 / 40 20 50 20 20
Camden 91 69 91 70 93 / 30 20 50 20 20
Crestview 92 69 91 70 91 / 20 20 40 20 40