Grants Pass, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

314
FXUS66 KMFR 051204
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
504 AM PDT Sun Apr 5 2026

.UPDATE...Aviation Discussion Updated.

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.PREV DISCUSSION... /Issued 1217 AM PDT Sun Apr 5 2026/

DISCUSSION...Satellite imagery early this morning shows a wide
expanse of high clouds moving over the area ahead of a weak
shortwave slowly moving north just offshore. A thermal trough set
up along the Oregon coast will keep us warm and dry through the
weekend with temperatures pushing into upper 70`s and perhaps
lower 80`s over some locations.

Fog will likely fill into the Umpqua Valley by sunrise as there
is some boundary layer moisture there, although the drier air
today could dry things out. Plus, the higher clouds could reflect
some of that long wave radiation back to earth. In any case, we
kept fog in the forecast, although confidence still isn`t high in
the formation.

Sunday will be another warm day as the thermal trough begins to
move farther inland. However, our temperatures stay put with highs
in the upper 70`s west of the Cascades and low 70`s east of the
Cascades.

Monday is an interesting day as the ridge breaks down and a short
wave moves into southern Oregon early in the day. A few models and
about 15-25% of GEFS/ECMWF ENS are bringing precipitation to the
Cascades and other portions of our forecast area. Looking at GFS
model soundings, there is convective available potential
energy(CAPE) along the Cascade crest with some of that CAPE
is between -10C to -20C. The latest and greatest experimental
rapid refresh forecast system(RRFS) is modeling echos >40dbz with
some lightning east of the Cascades mostly in our CWA. Therefore,
we put some thunderstorms in the forecast along the Cascades,
although they will most likely be showers with some occasional
rumbles of thunder. Its more of a question of where these will
develop not if they will develop. Keep a look out for showers east
of the Cascades on Monday as well.

By Tuesday, a cold/stationary front will settle over central Oregon
with a cutoff low off the coast of northern California. The
models are bringing a 10-20% chance of rain to the area. A trough
in Canada then slides down the Cascades and it seems the chances
of rain increase to about 50% on Wednesday. There is still a lot
of variability on Wednesday with some ensemble members keeping
things completely dry, while others bring in plenty of
precipitation with some thunderstorms. The variability could
continue give the split flow and cut off low in the Pacific.
Given the higher snow levels, don`t expect any significant snow
with the precipitation on Wednesday.

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.AVIATION...05/12Z TAFs...VFR conditions will persist through the
TAF period for most the area. Some areas of LIFR/IFR conditions
could return to the Umpqua Basin (including Roseburg) around sunrise
this morning. Over the coastal waters, LIFR/IFR conditions in marine
stratus may develop south of Cape Blanco, then spread into areas
north of Cape Blanco later today. Areas along the coast will see
increasing chances for LIFR/IFR conditions with marine fog and
stratus late this evening.

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MARINE...Updated 1200 AM PDT Sunday, April 5, 2026...Gusty north
winds will gradually ease today, although steep seas persist for the
outer waters into Sunday morning. Then, relatively calm conditions
are expected through early next week. Another thermal trough
develops next week, bringing a potentially extended period of strong
north winds and steep seas beginning Tuesday afternoon.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT this
     morning for PZZ370-376.

&&

$$