Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Mobile Alabama
521 am CST Thursday Dec 25 2014

Short term [today and tonight]...a weak surface ridge of high
pressure will build over the lower MS River Valley and central Gulf
states today and early tonight...then shift northeast to the eastern
Seaboard by early Friday. Skies will continue to clear today and early
tonight followed increasing clouds by early Friday morning. A light
northerly flow will shift east to southeast late today and overnight
allowing better low level moisture to begin advecting inland by
early Friday morning. With this pattern some patchy fog may be possible
near sunrise Friday. will be rather pleasant with
near seasonal temperatures and better sunshine compared to the last few
days. As for temperatures will lean very close to the current mav guidance
through tonight making only minor tweaks near the coast due to the
cooler near waters and for consistency with surrounding weather forecast offices. Today
high temperature will range from the middle to upper 50s for most areas with
lows mostly in the middle 30s inland...and the lower 40s near the
immediate coast. 32/ee

[friday through Saturday night]...clouds will increase throughout
the day Friday as the surface high over the Middle Atlantic States
shifts east over the western Atlantic...bringing moisture back into
the region. A large upper high pressure system will remain over the
Bahamas as an upper trough over The Rockies slowly moves over the
Central Plains by late Saturday night. A 300mb jet maximum ahead of the
trough will increase to between 130 to 170 knots from the Southern
Plains to the northeast Continental U.S. Region by late Saturday night. Light
southerly 850mb winds on Friday will only increase to between 20 to
40 knots Saturday afternoon through the overnight hours. Overrunning
will also allow our precipitation chances to gradually increase
Friday night...but no thunderstorms are expected. A deep southwest
flow will allow precipitable water values to climb between 1.7 and
1.9 inches by noon Saturday. Numerous showers and a chance of
thunderstorms are still forecast for Saturday and Saturday night.
MLCAPE will remain below 200 j/kg on Saturday...but 0-1km helicity
values are expected to increase from 100 to 200 m2/s2 along the
coastal sections...and from 200 to 300 m2/s2 inland areas. At this
time we still do not anticipate any severe storms on Saturday...but
a few strong storms are possible...especially inland.

High temperatures Friday and Saturday will be in the low to middle 60s.
Lows Friday night will range from 46 to 54 degrees inland areas...
and from 55 to 59 degrees along the coastal sections. Lows Saturday
night will range from 57 to 63 degrees. /22

Long term [sunday through thursday]...the GFS and European model (ecmwf) models are
in better agreement throughout the long term...with the European model (ecmwf) now
coming in with more precipitation compared to previous runs. The
large upper high pressure system centered over the Bahamas will
remain quasi-stationary through Sunday night...but now gradually
shift southward over the Caribbean Sea Monday through midweek. An
upper level trough will extend from Ontario Canada to northern
Mexico. But now no cutoff upper low forms on the southern end of the
trough over north central Mexico. Instead...the upper trough remains
as an open wave and will shift eastward and deamplify throughout the
day. Meanwhile...a second shortwave passing over the northwestern
Continental U.S. Will move southeast...and now carves out an Upper Cutoff low
over northern California and northern Nevada that will move south
over Southern California by late Tuesday night. This upper low will
then move over the Desert Southwest on Wednesday.

At the surface...there will be a large high pressure system over the
western Atlantic on Sunday...with an inverted surface surface trough
extending from southwest Canada to the western Gulf of Mexico. Weak
embedded surface lows may form over the southeast states as the
trough migrates eastward...but the primary focus will be on the
trough itself. A deep southwest flow ahead of these features
maintain precipitable water values between 1.2 and 1.7 inches on
Sunday. We still expect numerous showers with a chance of
thunderstorms to continue northwest of I-65 on Sunday...with
scattered showers and a slight chance of thunderstorms southeast of

A cold front approaching the region from the northwest Sunday
morning will slowly pass southeast across the forecast area through
Sunday night. This will bring drier air across the region the first
half of the work week...but will keep isolated showers in the
forecast mainly Monday night into Wednesday morning as both models
are wavering from run to run with the strength of the cold front.
Return flow Wednesday night and Thursday should bring scattered
showers back into the forecast area. High temperatures will be above
normal Sunday and Monday...and near normal Tuesday through midweek.


25.12z kmob/kbfm and kpns taf cycle
VFR conditions through 26.12z. A few middle to high clouds early today
reforming by early Friday morning. Some patchy fog will also be
possible by early Friday morning. A light northerly wind flow will
shift mostly southeast at 3 to 5 knots late today and tonight.


Marine...northerly winds and seas will continue to diminish through
early this afternoon. Weak high pressure will build over the north
central Gulf through this evening then move northeast to the eastern
Seaboard late tonight in response to a vigorous upper level
disturbance and broad surface low approaching from the west. With
this pattern a light to moderate east to southeast wind flow
develops early Friday then builds through midday Saturday...shifting
mostly south to southwest as the low center approaches from the
southwest. Scattered to numerous showers and thunderstorms are
expected by the weekend with the best coverage occurring Saturday
through early Sunday morning. A light northerly flow develops by
early next week. 32/ee


Preliminary point temps/pops...
Mobile 57 41 63 54 66 / 05 00 10 40 80
Pensacola 57 42 62 54 65 / 05 00 05 40 80
Destin 57 45 61 53 65 / 05 00 05 30 70
Evergreen 57 33 62 47 62 / 00 00 05 20 80
Waynesboro 57 35 62 49 63 / 00 00 10 30 90
Camden 57 34 61 47 62 / 00 00 05 20 80
Crestview 59 32 62 49 63 / 05 00 05 30 70


Mob watches/warnings/advisories...


National Weather Service Glossary of Abbreviations