Eckster's take early on for up here....
.LONG TERM /SATURDAY THROUGH THURSDAY/...
12z deterministic models and latest ensemble information have
come into better agreement today with regards to a potentially
significant winter storm for portions of our forecast area
Sunday night through Tuesday. However with that said, this is a
complex, potentially 2-part system which may spur further model
outcome changes going forward over the next couple of days.
Therefore, forecast confidence is precip type(s), timing, and
amounts remains low.
After a fair weather Saturday and probably much of Sunday, a
large an amplifying trough will approach from the west along
with a significant slug of moisture advection and forcing for
ascent. At the same time, mid and upper level confluence well to
the northeast of our region will reinforce cold dry low level
air over the forecast area. Multi-model and ensemble consensus
was followed here and shows a rather impressive slug of QPF
arriving across southwestern zones late Sunday, then gradually
progressing northeastward Sunday night. The emphasis is on
the word gradually as low level dry air and synoptic scale
downward motion will make for a slow go for the leading edge.
Precipitation type is very uncertain, but a mix of snow, sleet,
and freezing rain appears to be a good bet based on the latest
consensus thermodynamic profiles. Some rain will be possible
for a time in the far southeast as boundary layer temperatures
remain somewhat warm.
As previously mentioned, the pattern is complex with a lot of
amplification and "blockiness". Therefore, it doesn`t make much
sense at this time to try and pinpoint exact timing, dominant
precipitation types, amounts, and impacts this far out. More
suppression would lead to a farther south scenario as less
precipitation for our CWA as a whole. A farther north scenario
with less upstream blocking would result in a warmer scenario
for most. However, the main message here is that there is the
potential for a significant amount of snow, sleet, freezing rain
and possibly some rain for the forecast area centered around
Sunday night through Tuesday as a prolonged, 2-part system may
take shape. At this time, consensus for the location of the
heaviest amount of precipitation is across southern and coastal
zones, but this could easily change.
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