Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 301607
Area Forecast Discussion
National Weather Service Medford OR
907 AM PDT THU JUN 30 2016
.DISCUSSION...Updated the forecast to include a slight chance of
thunderstorms for Friday afternoon and evening across southern and
eastern Modoc County. Although moisture is questionable, the high
resolution WRF indicates storms developing in this area. Any
storms that do form would be mostly dry.
For much of the forecast, persistence will work with temperatures
only varying a few degrees over the holiday weekend. Will take a
look at Saturday afternoon to see if thunderstorms are possible
over the eastside.
.PREV DISCUSSION... /Issued 500 AM PDT THU JUN 30 2016/
Updated aviation discussion.
DISCUSSION...An upper trough will remain parked over the Gulf of
Alaska through Friday with benign zonal flow south of this low
into the Pacific Northwest. This will result in little change in
our weather over the next 48 hours. We will see some cumulus
buildups at times over the mountains due to instability, but we
lack sufficient moisture or forcing to get anything more. The
marine layer will drive weather at the north coast, and nocturnal
surges into the western Umpqua will continue. Inland, warm to hot
and sunny weather continues.
Over the weekend and into next week the Gulf of Alaska low
gradually moves inland over western Canada with its trough axis
moving over us. Temperatures will remain warm through the weekend
then begin to fall back closer to normal early to mid next week.
Thunderstorms cannot be entirely ruled out over the mountains,
especially as the trough axis moves in early next week, but there
isn`t enough evidence to put any storms in the forecast yet. The
models generally agree that while moisture increases and at least
some dynamical forcing arrives early next week, instability
remains fairly low. In other words: the vast majority of us are
unlikely to see any discernible change in the day to day weather
through the next week or so. -Wright
AVIATION...For the 30/12Z TAF cycle...Current fog product shows
the marine stratus confined to the Coquille Basin. Meanwhile
skies are clear along the coast. However, there`s still a chance
for MVFR cigs to develop at North Bend between around 14z. For now
we`ll leave those conditions in the TAF, but confidence is low to
medium the lower conditions will develop. Elsewhere VFR cigs will
continue for the next 24 hours. Once again, gusty winds are
expected along the coast by late morning and late this afternoon
and evening forthe inland terminals. -Petrucelli
MARINE...Updated 300 AM PDT Thu 30 June 2016...Little variation
in the pattern is expected through early next week. Gusty north
winds with very steep wind driven seas will continue through the
weekend with offshore high pressure and a thermal trough along the
coast. Gale force winds will continue through at least tonight.
The models suggest winds will diminish some by Friday morning,
then could get close to gales in the southern waters, mainly 10 nm
from shore Friday afternoon. Confidence is not high we`ll get to
gales Friday afternoon, so we`ll continue to go with the gales
expiring at 12z Friday morning. Later shifts will need to
reevaluate if future model runs trend higher with the winds. At
the very least confidence is medium to high we`ll have high end
small craft conditions for the southern outer waters and low end
small craft mainly 5 nm from shore south of Port Orford Friday
morning through the weekend. -Petrucelli
FIRE WEATHER...300 AM PDT Thu 30 June 2016...
Little variation in the pattern is expected through the weekend.
Hot and dry weather will continue with gusty west to northwest
winds in the afternoon and early evening hours. However both
temperatures and winds will not be considered extreme. Offshore
high pressure and a thermal trough along the coast will persist
through the weekend. The good news is the threat for thunderstorms
are zero. However the continued hot and dry conditions will lead
to further drying and curing of grasses. A couple of weak
disturbances will pass by over the next couple of days, but the
models continue to show limited moisture at the mid levels.
Therefore we are only expecting very limited and moderate cumulus
build-ups... mainly from the Cascades eastward.
An upper low in the Gulf of Alaska will move east into northern
B.C. this weekend. This will bring little change over our area.
The main effect will be slight cooling and bring increasing
westerly winds on the east side of the Cascades on Sunday. In the
eastern zones...sustained winds of 15-20 mph will be common and
coupled with low afternoon minimum RH of 10-20%. West side winds
will be more common at 10-15 mph with minimum RH of 15-30%.
Further cooling is possible Monday through Next Wednesday with
slightly higher RH`s in the afternoon. The models show the
aforementioned upper low remaining in northern B.C. but there will
be several weak shortwaves rotating around the low and moving
into our area. Despite the cooling, afternoon temperatures are
still expected to be near normal for this time of the year.
Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Friday for
Gale Warning until 5 AM PDT Friday for PZZ356-376.
Small Craft Advisory for hazardous seas until 5 AM PDT Friday