Area Forecast Discussion
Issued by NWS Huntsville, AL
FXUS64 KHUN 301120 AAA
Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
620 AM CDT MON MAY 30 2016
For 12Z TAFs.
(Issued 315 AM CDT MON MAY 30 2016)
Satellite imagery this morning shows TD Bonnie spinning over the SC
coast and some mainly high level cirrus moving through the TN Valley
from convection over the ARKLATEX. Expect mostly sunny to partly
cloudy skies today as high pressure begins to build into the midwest.
It will be a warm Memorial Day across the TN Valley as temps climb
into the upper 80s to lower 90s. We may see a brief reprieve from
the muggy conditions this afternoon as we mix down drier air aloft.
With the high to the north and TD Bonnie to our east, there will be a
increase in the pressure gradient over the region, resulting in a
slight breeze out of the N/NW this afternoon.
One caveat to the N/NW winds is the upslope component over the
Cumberland Plateau. Good heating this afternoon and the little bit of
upslope lift may allow for a few isolated showers and thunderstorms
to form over the higher terrain of NE AL, Southern Middle TN, and
northern GA. The latest CAM models and NCAR Ensemble guidance do
suggest some isolated development over this region. Confidence
remains low but have introduced low end PoPs for this afternoon over
Jackson and DeKalb counties. All activity will end by sunset leaving
mostly clear skies tonight. A repeat of today is expected on Tuesday
with temps climbing another degree or two but with the ridge axis in
place, increased subsidence should prevent any convective development.
Winds begin to shift from the N to the SE during the day on
Wednesday as the high pressure over the Midwest begins to translate
eastward. One interesting thing to note with this transition is that
in typical situations when our winds are out of the east we see drier
air being advected into the region. However, in this case the
rainfall from TD Bonnie has left a good deal of tropical moisture
over N GA/SC and models are picking up on some of this mid to upper
60 degree dewpoints being advected towards the region. The overall
strength of the moisture advection is rather weak but if we can tap
into some of this increased moisture we may see a slight up-tick in
convection that develops over the higher terrain to our east.
However, there may still be enough subsidence to prevent scattered
development over the TN Valley.
For the latter half of the week models remain in good agreement in
developing an upper level system of the Intermountain West and
carrying it east across the northern CONUS. A weak cold front is
expected to develop and head towards the area Wed into Thur as the
system moves through the Great Lakes. This front although weak, when
combined with increased gulf moisture due to winds becoming more
southerly, should be able to provide the additional forcing necessary
for more scattered showers and thunderstorms. But due to the
uncertainty in the timing of activity will keep PoPs in the chance
category for Thursday.
There is also good consistency from models in the development of a
closed/cut off low over central TX on Thursday. The interaction
between the system moving to our north and low over TX looks like it
will create a shear axis that will be located near the region through
the weekend. Have kept chance PoPs in place through much of the
extended due to our proximity to the shear axis. The cut-off low
looks to remain in place for much of the far extended period as the
persistent ridge/omega block that has been over our neck of the woods
builds over the Intermountain West. This will likely keep precip
chances in the forecast as winds shift to the NW and as is typical
for this time of year, we get decaying MCS`s that form of the Midwest
each afternoon and evening.
For 12Z TAFs:
VFR conditions will continue across N AL/S Middle TN for the next 24
hours. Northerly winds of 10 kts with gusts to 15 kts are expected
to develop after 30/16Z and continue through 31/01Z. Isolated -tsra
are possible over NE AL, and should not affect the TAF sites.
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