Severe Storm Outlook Narrative (AC)
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ACUS02 KWNS 190607
SWODY2
SPC AC 190606

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1206 AM CST Sun Feb 19 2017

Valid 201200Z - 211200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
General thunderstorms are forecast over east Texas into Louisiana
and northward into the Upper Midwest.  A few thunderstorms are
possible near the Oregon and northern California coast late Monday
night.

...Synopsis...
A large-scale upper trough will slowly move eastward across the
central US and feature a shortwave trough over the south-central
Canada and an equatorward mid-level trough located over the
south-central states.  A weak surface low will migrate eastward
across the Upper Midwest as a cold front pushes into southwestern MN
by late afternoon.  Another decaying frontal segment will ease
towards the TX coast and serve as a focus for shower and
thunderstorm activity.

...northwest Gulf Coast...
Ongoing band of showers/thunderstorms Monday morning over the TX
coastal plain will gradually move eastward into LA and the Gulf of
Mexico.  Although strong mid- to high-level flow is forecast, weak
instability will likely limit storm intensity as mid-level lapse
rates are forecast to weaken prior to the start of the day 2 period.
Nonetheless, a broken band or two of thunderstorms may perhaps pose
a localized gusty wind risk during the morning before storms move
off the coast.

...Upper Midwest...
A plume of seasonably rich low-level moisture (dewpoints in the mid
50s) over IA/MO will advect northward into MN during the day.
Models continue to suggest a period of showers/isolated
thunderstorms during the morning to midday hours within a warm air
advection regime.  The antecedent clouds will likely delay stronger
surface heating ahead of the front.  Needless to say, only weak
buoyancy is expected and forecast soundings show several hundred
MUCAPE.  Although a strong storm cannot be ruled out, organized
severe weather is not anticipated.

...northern CA coast...
A mid-level speed max is forecast to move onshore late in the Day 2
period.  A moist onshore air mass will become marginally unstable
owing primarily to a cooling temperature profile (-20 to -28 degrees
C during the afternoon to late night period).  A possible scenario
includes a strongly forced and shallow convective band moving ashore
and yielding a risk for locally strong gusts near the immediate
coast.

..Smith.. 02/19/2017

$$


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