Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 271358
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
658 AM PDT WED JUL 27 2016

Updated Aviation, Marine, Fire Weather, and Climate discussions...

.AVIATION...27/12Z TAF cycle...
Low clouds and patchy fog along and near the coast, mainly in Coos
and coastal Douglas Counties, are expected to dissipate and retreat
to the coastal waters this morning by about 18Z, then return to the
around 03Z Wednesday evening. Elsewhere, VFR conditions with clear
skies will continue through the TAF period. Moderate to strong and
gusty winds are expected for most areas along and west of the coast
for most of the TAF period. BTL/DW

&&

.MARINE...Updated 630 AM PDT Wednesday, 27 July 2016...
The forecast remains on track for strong gales in most of the
coastal waters area south of Cape Blanco through Sunday. Recent
model guidance also indicates a similar wind regime may very well
continue into next week, as well. Polar orbiting satellite data
overnight through this morning confirms winds of 30 to 45 knots
between buoys 15 and 27 in the southern Coastal Waters south of Cape
Blanco. Have, therefore, continued Gale and Small Craft Advisory
headlines. Have also added a Hazardous Seas Warning for the northern
Coastal Waters from Cape Blanco north to Florence between about 20
and 60 nautical miles of the coast, as seas should rise to around 10
feet late this afternoon through tonight. Through Thursday winds
just above the surface increase to as much as 50 kt. As a result,
the area of gales is expected to expand and there may be occasional
storm force gusts over a small area west of Brookings between
approximately 10 and 40 NM from shore this afternoon through
Thursday evening. BTL

&&

.FIRE WEATHER...Updated 645 AM PDT Wednesday, 27 July 2016...
High pressure centered offshore will continue the hotter and drier
trend through Friday. Thermal low pressure along and near the coast
will continue to result in light to moderate northeast winds in the
Coastal Mountains along with moderate humidity recoveries nights and
mornings. Winds will be generally light away from the coast, though
a bit breezy and gusty in the evenings, following typical mountain-
valley cycles.

Friday through Saturday weak low pressure west of California will
stretch northeastward bringing a possibility of isolated
thunderstorms from about the Marble Mountains east-northeastward to
the Warner Mountains. While numerical models had clearly backed off
on this possibility yesterday, there has been a clear trend in
yesterday evening`s and today`s guidance in showing the 500MB ridge
axis shifting more to the northwest, enough to put us under the
influence of a weak impulse riding northeast from the weak low off
of the California coast and the outer fringe of the monsoon. Current
guidance is consistent among the models in showing sufficient
parameters for isolated thunderstorms over and near the Trinity Alps
Friday evening, possibly drifting northeastward. Friday evening
we`ll need to watch the Modoc to Lakeview corridor, though current
guidance indicates parameters to be marginal there. Saturday the
threat shifts northeastward along with more cooling aloft. This puts
the main threat over Lake County. It should be noted that the
possibility of thunderstorms is still slight at this time, so stay
tuned, as we`ll be gaging details and model consistency over the
coming days.

There still remains the potential for a dry cold front and gusty
winds to occur both ahead of a cold front on Saturday and behind it
on Sunday. Humidities will remain low over the weekend, so the
combination of low humidity and gusty winds will lead to at least
elevated fire danger, especially for east side locations. It will
also bring a 5 to 10 degree cool down this weekend into next week
which will eventually bring humidities up a few percent, at least
west of the Cascades. BTL/Wright

&&

.Climate...Updated 650 AM PDT Wednesday, 27 July 2016...
July 2016 is currently on track to finish 0.2F below the 1981-2010
normal for the month of July for the Medford Airport. This is true
even with the hot temperatures currently in the forecast. The last
time this location experienced a below normal temperature month was
November 2015. Before that the last below normal temperature month
was January of 2014. BTL

&&

.DISCUSSION... /Issued 330 AM PDT WED JUL 27 2016/

SHORT TERM...An upper ridge will remain in place through Friday
with little change in the hot temperatures. A coastal thermal
trough will bring gusty east to northeast winds to the coastal
mountains and gusty northerly winds to the coast. Of note, models
have trended towards bringing mid level monsoon moisture into
southern and southeast portions of the area on Friday. This will
bring a slight chance for thunderstorms into the area, mainly for
Northern California zones. On Saturday, a trough will move inland
north of the area and bring a dry cold front inland. A broad
trough pattern will remain over the PacNW on Sunday with
relatively cooler temperatures.

Today and Thursday, hot and dry conditions are expected over
inland areas. Temperatures are expected to reach the low 100s
today and into the low to mid 100s on Thursday for some western
valleys, including the Rogue, Illinois, and Shasta Valleys.

On Friday, hot temperatures continue. Additionally, models have
shown agreement in the last couple runs of the 00z and 06z GFS
and the 12z and 00z ECMWF with bringing mid level monsoon
moisture up from the south into Siskiyou and Modoc Counties and
into southern Klamath and southern Lake Counties. Weak instability
is also present and will allow for cumulus buildups and some
possible thunderstorms. However, any significant triggers for
thunderstorms are lacking. So have only added a slight chance for
thunderstorms in over southern portions of the CWA. The NAM 00z
run also indicates similar moisture and instability for southern
portions of the CWA but indicates a cap and less chance for storms
to develop. Will need to monitor this portion of the forecast for
thunderstorm potential.

On Saturday, with an upper trough moving inland to the north and a
front moving inland, winds will increase in the afternoon and
evening for areas east of the Cascades. Additionally, models
indicate a slight chance for showers or thunderstorms over eastern
and southern portions of the CWA. Have only put a slight chance in
for thunderstorms in the higher terrain areas of eastern Modoc
and eastern Lake Counties since moisture is limited to the west.

Temperatures are forecast cool some on Saturday, but remain above
normal for most locations, and then cool further, reaching normal
or slightly above normal on Sunday.

&&

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

CA...None.

Pacific Coastal Waters...
- Small Craft Advisory until 5 AM PDT Monday for PZZ350-356-370-376.
- Gale Warning until 5 AM PDT Monday for PZZ356-376.
- Small Craft Advisory for winds from 5 PM this afternoon to 5 AM
  PDT Thursday for PZZ370.
- Hazardous Seas Warning from 5 PM this afternoon to 5 AM PDT
  Thursday for PZZ370.

$$

CC/BTL



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