Day 1 Severe Weather Outlook

Valid 081300Z – 091200Z


Thunderstorm areas are not expected from today through the overnight

In mid/upper levels, the eastern CONUS trough will move eastward and
weaken considerably through the period, as a series of shortwaves
moving through the associated cyclonic-flow field dampen and head
out over the Atlantic. Upstream, a complex perturbation —
containing several prominent/mesoscale vorticity maxima — is
evident in moisture-channel imagery over southern BC and the Pacific
Northwest. Split flow aloft will develop late in the period over
the West, as the eastern vorticity lobe(s) of the trough eject
eastward, and a strong/western component digs south-southeastward
through OR and northern CA. By the end of the period, this should
result in separate shortwave troughs: one over the north-central
Plains and the other over parts of northern NV and central/northern
CA. The latter will continue amplifying into day-2, forming a
closed cyclone over/near southern CA, as discussed in the outlook
for that period.

At the surface, a cold front was analyzed at 11Z across the northern
Bahamas to near the northernmost coastline of Cuba, becoming
quasistationary from there across the south-central Gulf. The air
mass behind this front, across the central/eastern CONUS, should
remain too dry and/or stable in low levels to support thunderstorm
areas until day 2. A weak low near CTB will move/redevelop
southeastward to near RAP by 00Z, with a trailing cold front moving
southeastward over portions of WY and UT. By 12Z tomorrow, the low
should be located near FSD, with cold front across east-central NE,
west-central KS and northeastern NM. A broad zone of low-level warm
advection and moisture transport will be underway to its southeast
by then, across portions of the southern Plains to lower Missouri
Valley. However, the combination of moisture, instability and lift
should be too weak to support thunder areas until day 2.

..Edwards.. 02/08/2020


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