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Day 1 Outlook Day 2 Outlook Day 3 Outlook Days 4-8 Outlook

Day 1 Outlook Convective Tornado
Hail Wind
Categorical Day1 0100Z Outlook
Images courtesy of the NWS Storm Prediction Center
 Forecast Discussion

ACUS01 KWNS 181929
SPC AC 181927

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0127 PM CST Sun Feb 18 2018

Valid 182000Z - 191200Z


A few thunderstorms are expected from the southern Plains today to
the middle Mississippi Valley tonight, and sporadic lightning
strikes may also occur along the northern California and Oregon
coasts in addition to parts of the interior West.  Isolated large
hail will be possible this evening in parts of west and southwest

No change was made to the previously issued forecast.

..Smith.. 02/18/2018

.PREV DISCUSSION... /ISSUED 1026 AM CST Sun Feb 18 2018/

Large-scale pattern amplification is underway with a developing
western trough and eastern ridge.  Cold midlevel temperatures and
associated steep low-midlevel lapse rates will support the threat
for low-topped convection and isolated thunderstorms along the
Pacific coast as the midlevel trough digs southward.  Downstream,
this amplifying pattern will favor air mass modification and
northward-northeastward moisture transport across the southern
Plains and lower MS Valley, to the east-southeast of a lee cyclone
across the High Plains.  Isolated thunderstorms are ongoing across
southwest TX in association with a weak lead shortwave trough.  This
regime supporting moistening above the ground and elevated
thunderstorms will spread northeastward in conjunction with a
strengthening low-level jet from TX to the mid MS Valley through

...West/southwest TX late this afternoon/evening...
There will be a small window of opportunity for a strong storm or
two late this afternoon/evening near and south of Midland.  Surface
heating along a weak surface trough/dryline and boundary-layer
dewpoints in the mid-upper 50s feeding up the Pecos River valley
will support surface-based CAPE near 1000 J/kg and weakening
convective inhibition.  Effective bulk shear around 40 kt and
midlevel lapse rates near 7 C/km could support an isolated supercell
capable of producing marginally severe hail.