Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Birmingham Alabama
1119 am CDT Monday Apr 27 2015
Temperatures look pretty good for today. Boundary across the coast
will keep things rather stormy there. Although most guidance keeps
activity south of central Alabama during the day today...activity
is awefully close and the hrrr is indicating that we could get a
little shower activity scrape our southern fringe counties. Threw
in some low 20 probability of precipitation across the southern fringe counties. Again...
most of the activity for here should hold off until tonight into
Tuesday as the low progresses across the coastal region.
12z taf discussion.
Next 18 hours will be good for all of central Alabama with VFR
conditions. By 6z...low clouds and rain will begin to slide
northeastward into southern portions of the area. Expect MVFR ceilings
and rain to work into mgm and toi by 9z. The rain will work into
the northern sites after 12z and will likely be included in the
next set of tafs.
/issued 508 am CDT Monday Apr 27 2015/
Cooler and drier air has spread across all of central Alabama early
this morning. The cold front has moved into extreme southern Alabama
and the northern Florida Panhandle. Temperatures are ranging from
the very cool middle to upper 40s in north Alabama to the middle 60s
across our southeast counties. As the dry air remains in place
during the day today...we'll have one more day of rain-free
conditions before moisture quickly increases from the south and west
overnight tonight and during the day on Tuesday. The very potent
upper level closed low over the southwest states will slowly move
eastward. Southwesterly flow aloft will transport plenty of moisture
northeastward...in addition to cyclogenesis along the Gulf Coast.
The surface low is still expected to travel generally along the
coastline...with model guidance in good agreement with this
solution. The only outlier is the NAM...which brings the low farther
north into southern Alabama. With the vast majority of solutions
keeping the low along the coast...the current forecast of no severe
thunderstorms for our area remains on track. If the low did track
farther north...there would be plenty of dynamics and instability
due to more moisture surging northward to sustain severe updrafts
at least across our far southern tier of counties. We'll continue
to monitor the latest trends in the track of the low...but the
last few guidance runs have been consistent with the southerly
So...with the low tracking off to our south...we'll still be able to
see widespread rains and enough instability for a few thunderstorms
across the southern half of central Alabama. The highest rainfall
amounts will certainly be along our southern counties where
moisture values and thunderstorm chances will be highest. Farther
north of the surface low and warm front...winds will become
easterly at the surface and transport drier air from the east
across central Alabama. That drier air will limit thunderstorm
potential but elevated convection can't be totally ruled out. As
the surface low continues moving eastward through the day on
Wednesday...surface flow will turn around to the north as what's
left of the upper low moves eastward across the Tennessee Valley.
Scattered to numerous showers will remain possible during the day
on Wednesday...which will keep temperatures quite cool for this
time of the year. I went ahead and started trending toward the
cooler end of guidance during the day on Wednesday...as we could
be looking at highs at least 15 degrees below normal for some
The cooler trends will continue through the end of the week with a
large eastern Continental U.S. Trough expected to develop by Thursday. The GFS
is advertising a very potent closed upper low moving southward into
the southern Appalachians while the European model (ecmwf) has more of an open wave.
Regardless of those differences...temperatures will certainly remain
well below normal with a chance of showers across the northern and eastern
counties on Thursday. A crisp morning is expected on Friday for
the northern half of central Alabama as 40s are expected to be widespread.
Dry weather returns for the weekend as upper level ridging builds
in from the west and temperatures modify. Upper 70s to lower 80s
look to be in store for highs on both Saturday and Sunday.
Preliminary point temps/pops...
Gadsden 70 50 65 53 61 / 0 10 60 70 60
Anniston 72 53 66 55 62 / 0 10 60 70 60
Birmingham 71 53 65 55 63 / 0 20 70 70 50
Tuscaloosa 73 54 65 56 64 / 0 30 70 70 40
Calera 73 54 65 56 63 / 0 20 70 70 50
Auburn 75 56 65 56 63 / 0 30 70 70 60
Montgomery 77 57 69 60 66 / 20 50 70 60 50
Troy 78 58 69 60 67 / 20 50 70 60 50