Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 050911

Area Forecast Discussion
National Weather Service Reno NV
211 AM PDT THU MAY 5 2016


An increase in showers and thunderstorms is expected today as low
pressure approaches the California coast. Some of the storms
could be strong with frequent lightning and copious amounts of
small hail. Unsettled weather will continue into the weekend with
locally heavy rain possible. Drier, warmer weather returns next



Upper low moving toward the CA coast should lead to increased
instability through the day and combine with a south to north
oriented jet to produce widespread showers and scattered
thunderstorms through the day. The presence of the upper jet may
boost instability aloft well beyond that seen Wednesday when
increased cloud cover cut low level heating and limited the amount
of deep convection. The upper level diffluence is likely to aid in
the continuation of thunderstorms into the evening hours and
possibly overnight as the upper low moves slowly east toward
southern CA. Initially fast moving cells this afternoon mean the
primary threats will be small hail and gusty winds...but as the
mid level steering flow decreases into the evening hours slower
moving cells will mean the primary threat may transition to
moderate to heavy rain.

The slow movement of the low to the east will mean continued
instability Friday...but increased cloud cover and a lack of a
consolidated upper level jet support is likely to limit the
amount of thunderstorms compared to today. Still...slow moving
storms could create brief moderate to heavy rain and some
localized minor flooding.

The upper low moves east of the region Saturday...but a
deformation axis is likely to form on the back side of the low
with bands of precipitation developing across the forecast area.
For now it is difficult to pin point where any of these bands may
form. Again...cell movement appears to be fairly slow for Saturday
meaning any bands that form could produce significant rainfall
across parts of the forecast area. Extensive cloud cover and rain
could also make Saturday the coolest day of the short term period
with highs in the 50s and 60s. 20

.LONG TERM...Sunday through Wednesday...

Upper trough will finally begins its exit on Sunday with
decreasing shower and storm potential from north to south through
evening. Some stronger slow moving storms will still be capable of
small hail and heavy rainfall as the atmosphere will be unstable.
The main change to the forecast was to show a gradual decrease in
coverage across northern areas in the afternoon and central areas
by evening.

For Mon-Wed, both the GFS/ECMWF have trended a bit cooler as
shortwave trough drops down east side of ridge, delaying the warmup
until later in the week. We cooled temperatures down a few degrees
Tue-Wed, but if some of the MOS guidance is correct, temperatures
may need to be cooled further as a northeast gradient pushes cooler
and drier air in from the northeast. Isolated showers will be
possible along the Sierra crest. Otherwise, it should remain dry
as the bulk of moisture and instability stay east. Hohmann



Isolated thunderstorms across northeast CA and northwest NV will
continue through daybreak as that area remains in favorable region
of large scale forcing. Isolated showers/storms may develop farther
south toward KRNO/KCXP/KNFL early this morning, but the best
chances will be to the north.

Otherwise, showers and storms will be on the increase today as large
scale upper low moves eastward into CA/srn NV and dynamics/lift
spread across all areas. A few strong storms will be capable of
lots of small hail and moderate-heavy rainfall. Banding of
showers will be possible through Sunday with longer more
persistent periods of steady moderate rainfall and embedded
thunderstorms possible. Terrain obscurement and MVFR conditions
will be more prevalent in these bands. Hohmann


.REV Watches/Warnings/Advisories...


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