May 18, 2013
LONG TERM [Sunday through Friday]...
We continue to see model to model and run to run inconsistencies
with respect to the evolution of the upper level flow pattern and
associated frontal systems through the mid/long range periods.
Confidence in this part of the forecast remains below average. We
generally used a blend of HPC guidance and gridded MOS for most
fields. Details will need to be resolved later, but the general
trend shows a retreating ridge at the start of the period which
brings another day of warm temps on Sunday. A frontal system will
approach from the west. Chance PoPs (30-50%) were used with
highest northwest. As short wave energy moves from the Southern
Plains out into the Mid South, a wave develops on the front and
highest PoPs (40-60%) are realized on Monday as the front moves
through. We generally followed the GFS solution after that with
high pressure building eastward along the Gulf Coast in the wake
of the front. Since this air mass is of Pacific origin, temps will
generally be close to average behind the cold front. The next
frontal system is progged to approach on Thursday.
It should be noted that the 12/12Z Euro was much less progressive
and showed a deepening trough with a massive coastal low bombing
along the Southeast U.S. coast on Tuesday. The latest 00Z Euro is
closer to our preferred solution, at least in terms of sensible
weather locally.
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