Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 300920

Area Forecast Discussion
National Weather Service Medford OR
220 AM PDT MON MAY 30 2016

.Discussion...A strong upper level ridge will build into the West
Coast today and move across northern California Tuesday. This is
inducing a surface thermal trough in northern CA, which is nosing
into SW Oregon and leading to offshore flow. A significant warm-
up is expected across the area with high temperatures about 10
degrees above normal today, then about 15-20 degrees above normal
Tuesday. Coastal areas south of Cape Blanco will be warmest today
with the axis of the thermal trough overhead. Brookings should be
up around 80 degrees. Temperatures in the Rogue Valley will jump
about 5-7 degrees compared to yesterday with highs in the mid to
upper 80s. The thermal trough will push inland Tuesday and marine
air will return to the immediate coast, but it will turn even
warmer inland. Highs here in Medford on the last day of May will
reach at least the mid 90s. Interestingly, this will be the 1st
90+ degree day of the month of May.

An upper level short wave moving onshore well to our north will
suppress the ridge and force it into the Great Basin Wednesday,
but it will remain very warm inland with temperatures staying
about 15-20 degrees above normal. Models are indicating some mid-
level moisture and instability over the Trinity, Siskiyou and
Cascade mountains, but with weak forcing. We could get a cell or 2
to develop, so slight chance looks appropriate for these areas at
this time. That short wave to the north will continue to flatten
the ridge Wednesday night into Thursday, but cooling across the
area will only be slight and barely noticeable.

The upper ridge will rebuild over the area Friday and Saturday
with an upper level closed low positioned off the southern
California coast. Models are currently showing the warmest H85
temperatures on Saturday. Right now, we are forecasting 100
degrees in Medford on Saturday, which would tie the record set in
1935. Even with the upper low off the southern California coast,
there probably won`t be enough moisture/short wave activity to
generate any precipitation.

By Sunday, the upper level low approaches the CA coast (south of
SF Bay). There is some variance in the models with respect to
just when and where the upper low will move onshore into CA. But,
expect moisture and short wave activity to increase in the
southeast flow aloft Sunday. Therefore, we have slight chance to
chance POPs for showers and thunderstorms then. The upper low will
fill and an upper trough should move through with additional
shower/thunderstorm chances Sunday night into Monday. Spilde


.Aviation...For the 30/06Z TAF cycle...VFR conditions will
continue at all TAF sites through the TAF period. Stratus with
MVFR cigs is possible along the coast by morning, but offshore
flow will keep it patchy at worst. Gusty and moderate to strong
north winds will develop tomorrow afternoon, especially along the
coast. -Wright


.Marine...Updated 200 AM PDT Mon 30 May 2016...Small Craft
conditions will continue south of Cape Arago into this morning with
gusty north winds, and seas dominated by both steep wind waves and
fresh swell. Winds will increase later today across the waters with
Gales in the southern portion of the outer waters and Advisory
strength winds over the remainder of the waters. North winds will
then gradually decrease but remain strongest in the southern portion
of the outer waters late tonight through the middle of the week.
Advisory conditions are likely to persist in the outer waters
through Wednesday night. -FB


.Fire Weather...Next week will be warm and dry with a rapid
warming from Tuesday onward. Confidence is high that the valleys W
of the Cascades will see high temperatures in the 95 to 100 degree
range as the thermal trough shifts inland and remains W of the
Cascades on Tuesday and Wednesday. Expect minimum RH for western
valleys to be in the mid teens with fair to poor recovery Tuesday
night and Wednesday night. The thermal trough is expected to shift
east of the Cascades Wednesday but onshore push will be confined
mainly to Douglas County of Oregon.

Around Wednesday we will have to contend with thunderstorm chances
as southerly flow aloft strengthens and allows more moisture and
instability to spread north. Right now we see only the higher
terrain such as the Cascades/Siskiyous, Marble Mountains, the
mountains of the Fremont-Winema Forest being the most likely area
to see lightning strikes. Confidence is not high on how much rain
these storms will produce. By Friday instability appears to be
shunted to central California and we have removed thunderstorm
chance from the forecast. Hot temperatures inland will continue
into the end of the week. /FB


.MFR Watches/Warnings/Advisories...


Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT this
     evening for PZZ350-356-370-376.
     Gale Warning from 11 AM this morning to 11 PM PDT this evening
     for PZZ376.
     Hazardous Seas Warning from 11 AM this morning to 11 PM PDT this
     evening for PZZ376.


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