Quantitative Precipitation Forecast
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FXUS04 KWBC 141723

Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
122 PM EDT Wed Mar 14 2018

Prelim Day 1 QPF Discussion
Valid Mar 15/0000 UTC thru Mar 16/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr

Day 1


The strong low currently over the Canadian Maritimes will be slow
moving for the upcoming day 1...lingering over New Brunswick- Gulf
of St Lawrence area.  Snowfall intensities in the comma
head/deformation precip band affecting portions of the northeast
are expected to decrease as per latest hi res simulated
radars---but with cyclonic low to mid level flow persisting
through day 1---snow showers will persist. Additional moderate to
heavy snowfall likely from northern to central NY to the east of
lake Ontario---east northeastward into the favored terrain of
northern New England.

Across the Great Lakes---a reinforcing shot of cold air expected
to sink southeastward across the lakes region tonight into
Thursday.  This should support increasing lake effect snow showers
developing from northwest to southeast downwind of all the lakes.
Model consensus is for light to moderate precip/snowfall totals.

Rockies---Great Basin---central to southern California

The elongated full latitude mid to upper level trof will be
pushing inland from California---into the Great Basin---Southwest
and through the Rockies day 1.  Above average pw values ahead of
these height falls and the associated surface frontal boundary
will support widespread moderate to locally heavy precip totals
through the central to northern Rockies into eastern portions of
the Great Basin and across central to southern California.

Northern California into the coastal Pacific Northwest

Stronger height falls associated with a closed low off the B.C.
coast will be dropping southeastward along the Pacific Northwest
coast during Thursday.  This will help strengthen the low level
southerly to south southwesterly flow from northwest California
into the coastal Pacific Northwest.  This will support increased
shower activity Thursday across these areas with the greatest
precip potential from the northern Sierra into the northwest
California coast range and the far southwest Oregon coast range
where the upslope component to the strengthening low level flow
will be the greatest.  Northward into the coastal Pacific
Northwest the low level southerly flow will have a primarily
terrain parallel trajectory--with less precip amounts expected.

Elsewhere---light precip amounts possible over south TX as the low
level southerly flow strengthens off the western Gulf of Mexico.
Scattered showers also possible across southwest TX ahead of
shortwave energy moving east northeastward across northern Mexico
into southwest TX.



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