Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 kbmx 180842 

Area forecast discussion
National Weather Service Birmingham Alabama
242 am CST Mon Nov 18 2019

Short term...
/updated at 0241 am CST Mon Nov 18 2019/
through tonight.

Starting out this morning a touch on the foggy side at some
locations as the area is between the inverted trough to the east and
the cold front to the west. Most of the locations impacted are near
bodies of water or colder valleys, but there are enough locations
that we mentioned in the severe weather potential statement this morning. Will continue to monitor
to see if we need to upgrade to a dense fog advisory.

As we move through the day, the dry cold front will move through the
area. We will see an increase in clouds as we go through the day, so
partly cloudy skies can be expected. Highs will be limited to the
50s in the north and west, but mid 60s will be possible in the
southeast before the front works through. Skies will finally begin
to clear overnight from south to north as high pressure begins to
slide into the area. The added clouds will keep temperatures from
dropping too low with readings generally staying above freezing
in the north and in the upper 30s in the south.


Long term...
/updated at 0241 am CST Mon Nov 18 2019/
Tuesday through Sunday.

Northwest flow aloft will be present on Tuesday as a trough
departs to the east, and ridging builds over the plains downstream
of a digging trough over the northwest Continental U.S. And a cutoff low off
the coast of Baja California. Southwest winds at low-levels
associated with a weak surface trough will advect in a warmer air
mass from the Southern Plains, allowing temperatures to rise into
the mid to upper 60s except in the northeast counties where clouds
may linger the longest. Winds will go calm overnight Tuesday night
as a surface ridge axis moves overhead. The mid-level ridge axis
moves overhead on Wednesday as the baja cutoff low ejects over the
Central Plains as an open wave, and induces Lee cyclogenesis at
the surface. Meanwhile, another upper low will close off over
Southern California. Westerly flow aloft and a dry air mass will
favor a continued warming trend, and favored the warmest
mav/met/mex guidance for highs. Southerly winds over all but the
far eastern counties will result in somewhat milder overnight lows
Wednesday night.

The shortwave trough and associated surface low will lift up into
the Great Lakes region Thursday. The trailing cold front will
stall across the mid-south by Friday morning as it becomes
parallel to the flow aloft, and as the southwest Continental U.S. Upper low
begins to eject eastward towards the southern High Plains,
beginning to cause a wave of low pressure to develop along the
front over the Southern Plains. Weak waves in the southwest flow
aloft and increasing mid-level moisture could trigger a couple
showers in the northwest Thursday afternoon. Otherwise, pleasant
conditions are expected with highs in the low 70s. The front and
associated pre-frontal moisture axis will serve as a potential
trigger for shower development Thursday night. Deterministic
models have trended much drier for this period, but with a fair
amount of ensemble members being wetter, only made gradual changes
to the pops. There still continues to be model/ensemble member
spread for the Friday/Saturday timeframe regarding the shortwave
trough/upper low moving eastward from the Southern Plains and
possible phasing with the northern stream. This has associated
impacts on surface low development along the front and the
eventual cold frontal passage. Generally leaned towards the
European ensemble mean and wpc guidance through this period, with
highest rain chances appearing to be in the Friday night to
Saturday morning timeframe. Further refinement will be necessary
in later updates. Instability within the narrow warm sector
continues to be very limited, so will continue to leave out a
mention of thunder, but will continue to monitor. Dry conditions
will eventually move in behind the front ahead of another trough
moving into the western Continental U.S..



06z taf discussion.

Terminal forecasts retain much of the current trend. Other than a
brief period of patchy fog possible at anb/asn/mgm/toi, extended
VFR conditions through the period. A cold front will move through
the region on Monday afternoon. Central Alabama will hardly notice
this feature. No precipitation is forecasted and only some mid
and high level clouds expected at the terminals. Winds will be
calm to light and variable within an hour and last until 18z or so
Monday. The winds become west northwest around 6kts.

An upper level feature was moving by late this evening
accompanied by some mid and high level clouds. Then a slight
clearing break, then an upper trough moves in. The low level
moisture will remain north of the terminals through Monday, with
only a brief period of ceilings around 080-100. High clouds begin
moving back into the region at the tail end of the period.



Fire weather...

Dry conditions continue through much of this week with relative
humidity values above 40 percent each afternoon. Any localized
valley fog will lift quickly this morning after sunrise. In
general winds will be rather light through the period, with the
relatively highest winds on Monday out of the northwest. The next
chance of rain comes in the Thursday/Friday timeframe.


Preliminary point temps/pops...
Gadsden 58 34 61 36 66 / 0 0 10 0 0
Anniston 60 36 63 38 68 / 0 0 0 0 0
Birmingham 59 38 64 40 70 / 0 0 0 0 0
Tuscaloosa 60 38 67 40 70 / 0 0 0 0 0
Calera 60 36 64 39 70 / 0 0 0 0 0
Auburn 61 39 62 41 68 / 0 0 0 0 0
Montgomery 64 38 67 41 72 / 0 0 0 0 0
Troy 65 39 65 41 71 / 0 0 0 0 0


Bmx watches/warnings/advisories/...

National Weather Service Glossary of Abbreviations