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Area forecast discussion 
National Weather Service Huntsville Alabama
732 am CDT Friday Apr 18 2014

Update...
for 12z tafs

&&

Discussion...
/issued 321 am CDT Friday Apr 18 2014/
area radars are beginning to pick up a few echoes across the region
this morning, with the brunt of the precipitation still well south of
the County warning forecast area. This activity is associated with a surface low in the northern
Gomex, developing as the surface reflection of an approaching 500 mb trough
currently exiting the Central Plains as of 8z. As this feature
deepens, an upper low will develop in the Gomex as well later this
morning (by 12z), all shifting to the North/East for the first half
of the weekend (eventually ending up off the coast of the Carolinas
by Easter Sunday morning). In addition to this, another weak surface
cold front is located just northwest of the Tennessee Valley this morning,
with a few showers firing up along the MS river as isentropic upglide
increases in this region. Further west, two upper level lows are
arriving on the west coast; one over socal and the other in British
Columbia. These two systems will phase together later in the period,
bringing the next chance of rain to our area early next week.

Otherwise, for today, not much has really changed over the past 24
hours. Precipitation associated with the surface low to our south will
mainly be confined there, with the northern fringe of the showers
flirting with our southern/eastern counties today and tonight as the
system moves newrd. Given better agreement in the short term models
(wrf/hrrr/nam), have opted to increase probability of precipitation for southern/eastern
locations, and have also added probability of precipitation from 00-06z tonight as the rain
gradually shifts eastward.

Ridging aloft will build eastward into the region, making for a warm
and dry Holiday weekend. Daytime highs will be in the 75-80f range
with morning lows between 45-50f, making for great weather for
Easter egg hunts Sunday morning.

As the aforementioned West Coast systems traverse the Continental U.S. This
weekend and into Monday, they will phase just South/West of the Great
Lakes and a cold front will approach the County warning forecast area overnight Monday into
Tuesday. Showers and thunderstorms will be possible during this time,
and with better agreement with the models this morning, probability of precipitation were
increased during this time. With the front expected to weaken the
further south/east it travels across the area, only gusty winds and
heavy rainfall are anticipated.

Beyond this timeframe, ridging at the surface/aloft build into the area
and shift eastward, allowing southwesterly flow to maintain dry and warm
conditions across the Tennessee Valley. Afternoon highs in the upper 70s/lower
80s can be expected each day, with morning lows increasing through
the week. Wednesday morning lows will be in the lower 50s, but by
Friday, lows will have warmed to around 6o degrees ahead of the next
weathermaker approaching from the west. Models aren't in the best of
agreement on timing of this next front, so no changes will be made to
the extended portion of the forecast just yet.

12

&&

Aviation...
for 12z tafs...radar/satellite data confirm increasing impacts at
both mean sea level/hsv this morning from an area of low pressure located over
the NE Gulf. Although observation currently indicate broken as around 6-7 kft
beneath overcast cirrus...expect ceilings to lower to 3500 feet as light precipitation
spreads northward into the region. With the low-levels of the atmosphere
expected to become increasingly saturated early in the taf period...
have included -ra in taf for mean sea level between 18/14-20z and hsv between 14-22z
along with MVFR ceilings /2500 ft/. Conds will begin to improve by late
afternoon as the area of low pressure and accompanying precipitation shifts
steadily eastward. Scattered cirrus will remain possible at mean sea level through end of period...
with hsv likely impacted by wrap-around stratus in low-level NE flow.
Winds at both terminals will back from ESE-NNE/north-northwest with sustained
speeds remaining in the 5-10 knots range.

70/dd

&&

Hun watches/warnings/advisories...

Alabama...none.

Tennessee...none.

&&

$$

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