Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
418 PM EDT Mon Apr 01 2019

Valid 00Z Tue Apr 02 2019 - 00Z Fri Apr 05 2019

...The West...
Days 1-2...

Low pressure reaches the CA/OR border late tonight. Onshore flow
head/south of this feature will allow snow for the high terrain of
the Sierra Nevada and CA/OR Cascades with snow elevations around
7000ft per the NBM. The heaviest Day 1 snow will be over highest
terrain of the Sierra where WPC probabilities are moderate for 8
inches. The upper trough associated with the low shifts across the
Great Basin and Central Rockies to the central High Plains on Day
2. Snow elevations remain high ahead of the trough, around 7000ft.
Moderate probabilities for six inches in Day 2 extend from the
Wallowa Mountains of OR to the mountains of central ID, WY, UT,
and CO.


...Western Carolinas...
Day 1...

A southern stream trough over the southern Plains this afternoon
will reach the southern Appalachians late tonight with surface low
pressure developing off the GA/SC through tonight. The western
side of the the precip shield will get into higher portions of the
SC/NC Piedmont, but likely stay east of the Blue Ridge Mountains.
The 12Z NAM remains the coldest solution with several inches over
western SC late tonight. However, the 12Z GFS is more reasonable
thermally. Even still, the wet-bulb zero height gets below 500ft
AGL west of Charlotte and east of Asheville tonight. Therefore,
the low probabilities for one inch along the western NC/SC border
are appropriate. Although this is below watch/warning thresholds,
1" in April is rare for this area so would be significant if it
occurs.


The probability for significant freezing rain (0.25 inches) is
less than 10 percent all 3 days.


Jackson