Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/14/18
Area Forecast Discussion
National Weather Service State College PA
1039 PM EDT Thu Sep 13 2018
A deep easterly flow will maintain a cloudy and humid airmass
over the region through at least Friday. High pressure will
build in from the north for later Saturday and Sunday supplying
drier air that should result in lower humidity and some
sunshine Saturday afternoon and at least part of Sunday.
The remnants of Hurricane Florence could impact the region with
rain early next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Radar has gone very quiet over the last hour as the last of the
showers dissipated over northern areas. The HRRR keeps the CWA
dry into Friday morning so I backed off the POPs to just some
very low chances with the mention of fog/drizzle as the low
clouds are expected to move back in on the easterly flow. The
composite satellite imagery shows these low clouds over southern
New England and NE PA backing westward on the south side of the
big high sitting off the New England coast.
Current sfc dewpoints in the 60s to around 70F will lead to
another very mild overnight, with lows near normal highs for
this time of year.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Friday will offer little change from what we`ve had over the
past few days and strong persistence will be key to the
Somewhat stronger east to ESE winds several KFT AGL will help to
maintain thicker cloud cover, likely suppressing convection, but
also resulting in lower temps too by a few to several deg F.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Latest track of Hurricane Florence is slightly farther south and
a little faster than the past day or two. From here, solutions
diverge dramatically after Florence comes onshore (assuming it
does so), with some new solutions curving Florence remnants up
the Appalachians and over western PA in the Monday to Tuesday
timeframe. Mornings on Sat and Sunday may be gray with patchy
drizzle, only for ceilings to lift and allow afternoon sunny
breaks, particularly across northern PA as sprawling sfc high
lies across the region. The wildcard will be the trajectory of
flow around the W-E oriented ridge extending from central New
England to Newfoundland, whose extensive over- water fetch will
combine with Florence`s circulation to shunt western Atlantic
moisture into the mid Atlantic region.
Remnants of Florence may end up reaching the area Monday into
Tuesday with an increasing chance for showers and TSRA and bands of
locally heavy rain possible Monday through Tuesday. Should this
solution verify, a positive would be the forward speed of said
remnants getting caught up in freshening southwest flow, hopefully
minimizing the duration of heavier rain as Florence`s remnants whisk
through the region.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A moist, easterly flow off of the Atlantic Ocean will prevail
through Saturday morning. Mainly MVFR Cigs and VFR to ocnly
MVFR vsbys in light fog. As of 02Z all showers have ended.
Scattered low to mid decks will continue to thicken as cooling
couples with the low level moisture to bring another round of
IFR cigs overnight tonight into tomorrow morning. SREF and HREF
probability charts indicate ifr/lifr cigs will once again
become widespread after midnight and continue through 13-14Z
Friday. Have put a TEMPO in at BFD due to the fact the IFR cigs
will raise and lower through the early morning hours. Periods of
IFR will continue at most locations, with sites improving to
MVFR by 15Z at the latest and VFR into tomorrow afternoon.
Fri...Low cigs likely, mainly in the morning.
Sat...AM low cigs possible.
Sun...Patchy AM fog possible.
Mon...Rain/low cigs possible.
NEAR TERM...La Corte
Area Forecast Discussion
National Weather Service Glasgow MT
320 PM MDT Thu Sep 13 2018
Short Term (Thursday night through Saturday Night)...
The pattern over the area is dominated by southwest flow aloft
east of a trough whose axis basically runs down the Cascades. As a
result, several disturbances will move through the area triggering
periods of showers through the weekend into early next week (see
the Long Term Discussion for more on the effects locally below).
There appears to be a break on the way late Friday afternoon into
Friday evening before another disturbance triggers some showers
overnight Friday night and near the Canadian border on Saturday.
POPs for tonight & tomorrow were generally good to begin with, and
edits were made to try to reflect timing of the showers (based
loosely on the HRRR and RAP) with a general trend towards more of
a NAMish look by Saturday.
Clouds will also linger across most of the area through Saturday
night (showers chances may drop, but cloud cover doesn`t) with
some breaks possible Friday night in Phillips County and in the
Yellowstone Valley on Saturday.
Long Term (Sunday through Thursday)...
Southwest flow will still be over Northeast Montana Sunday as a
slightly deeper trough over the Pacific Northwest ejects eastward
into early next week. The main part of this trough looks to be
over the area Sunday night, bringing with it a chance for showers,
best chances along and north of the river.
A more zonal flow pattern will set up once the trough moves
through for the first part of next week. There will still be weak
impulses moving through the mean flow, which will continue to
bring precipitation chances to the region in addition to the
cooler temperatures (running several degrees below normal with
highs in the upper 50s to around 60).
Freezing temperatures remain possible along the Canadian border
by early next week during the overnight hours, and this could
result in a little snow mixing with the rain if showers are moving
across the region at that time.
FLIGHT CAT: VFR, slight chance of MVFR at times.
DISCUSSION: Rain showers will be move through the area through the
weekend. There`s an outside chance that MVFR visibilities could be
reached if/when a shower moves over a TAF location, but confidence
in this happening is low.
WIND: Light northeast to east tonight; east to southeast expected
Area Forecast Discussion
National Weather Service Lubbock TX
630 PM CDT Thu Sep 13 2018
Mixed signals about chances for low clouds and fog early Friday,
with some solutions led by the NAM taking things down fairly hard
again. While other solutions notably including the HRRR not so
big on late night stratus. We already have added stratus for
early Friday and will hold on to the mention for now, but reassess
depending on solutions trends later this evening. Otherwise,
expect VFR to dominate until later tonight, and by mid or late
Friday morning once whatever stratus layer lifts, it then breaks
.PREV DISCUSSION... /issued 238 PM CDT Thu Sep 13 2018/
Another 24 to 36 hours of quiet weather expected across the South
Plains area before the potential for a fairly wet weekend arrives
in the form of an upper level inverted trough. This inverted
trough will be the remnants of a tropical depression that was
located a couple hundred miles to the east-southeast of
Brownsville early this afternoon and will move to the northwest up
the Rio Grande. Rain chances Saturday and Sunday will favor areas
to the east and south of Lubbock. A closed circulation at 700 mb
will be well to the south of the forecast area, coming up toward
the southern Permian Basin. Thus, the best focus for heavy rain
will remain to the south as well. However, with rich deep layer
moisture in place across the area, some isolated heavy rain is not
out of the question.
Upper level high pressure begins to reassert control Monday as the
inverted trough dissipates. This will mark a return to an end of
precipitation chances and slightly warmer temperatures through
the middle of the week. The center of the ridge is progged to
shift eastward to the southeastern U.S., replaced in the western
CONUS by an upper trough, although there is a fair bit of
divergence amongst the models with the details of the solution.
Still, there is enough evidence for the return of storm chances as
early as Wednesday to merit their continued inclusion in the
forecast through Thursday.
Area Forecast Discussion
National Weather Service Medford OR
845 PM PDT Thu Sep 13 2018
A few changes to the forecast this evening as the Klondike fire
shows some active burning on north east side of the fire. Added
smoke and haze in the forecast tomorrow as result. We personally
think the HRRR Smoke might be under estimating the smoke output
tomorrow with possible burnout operations underway.
The widespread frost east of the Cascades also remains on track
as temperatures are about the same as yesterday. The thoughts from
the forecast this morning is that skies should clear out a bit
more tonight. Dewpoints are currently sitting in the mid 30`s and
we should drop below that in the east side valleys.
Read the discussion below for more information beyond tonight.
.AVIATION...For the 14/00Z TAFs...Coastal IFR ceilings have been
observed in the past hour, moving into North Bend. IFR conditions
should remain at the coast through Friday morning. VFR conditions
are expected to prevail inland into the early evening. Late this
evening and overnight areas of MVFR and IFR ceilings and
visibilities are expected to form across inland Coos and Douglas
counties, and isolated LIFR fog is possible. Conditions in those
areas are expected to improve between 15Z and 18Z Friday morning.
.MARINE...Updated 200 PM PDT Thursday, 13 September 2018... An
upper level trough over the Pacific Northwest will continue to
bring in a series of weak cold fronts through the weekend. Winds
and seas are expected to remain generally light through weekend.
The strongest of the weak fronts is expected Saturday night into
Sunday morning when southerly sustained winds in the vicinity of
Cape Blanco northward could reach 20 knots and seas may briefly
reach advisory levels west of the Cape. Northerly winds and wind
wave dominated seas are expected to return late Sunday into Monday
with advisory level conditions possible south of Cape Blanco
beginning late Monday or early Tuesday.
.PREV DISCUSSION... /Issued 525 PM PDT Thu Sep 13 2018/
DISCUSSION...An elongated upper trough extends off the West
Coast from an anchor low centered northwest of Hudson Bay. Cold
air aloft and the resultant instability is generating some
congested cumulus and isolated to scattered showers just inland
from the coast in portions of northern Curry, northwestern
Josephine, Coos and western Douglas Counties. Elsewhere inland,
it`s mainly sunny this afternoon with just some fair-weather
cumulus and temperatures more indicative of early October, rather
than mid-September. The showers should diminish quickly this
evening as the sun sets and instability wanes.
Mainly clear skies over the east side tonight into Friday morning
will cause temperatures to drop into the 20s and lower 30s in
many areas. A freeze warning is out for this at NPWMFR. It`ll be
cool west of the Cascades too with some outlying areas around
Medford dropping into the lower 40s.
We`ll remain in a broad west-southwest flow aloft Friday, so
expect mainly sunny skies and temperatures similar to or perhaps
up to a few degrees higher than today. Another cold night is
expected Saturday night east of the Cascades, so we went ahead and
issued another Freeze Watch. These may be the last freeze
headlines for some areas over there since we`re expecting
multiple days of below freezing temperatures. We`re also entering
the season where, climatologically, frost/freezing conditions
become much more likely over the east side.
Energy digging southward on the back side of the long wave upper
trough will form a closed low near the British Columbia coast
Saturday. The closed low will press onshore north of Washington
Saturday night into Sunday and this will send a cold front onshore
through the Pacific Northwest. Once again, we`re not expecting
widespread rainfall with this system. Precipitation chances will
be highest along the coast and NW of the Umpqua Divide, where they
may be able to squeeze out a tenth of an inch in some areas, but
most places will have less than that. Precipitation is unlikely to
reach Medford and areas east of the Cascades will stay dry. This
system will cause some gusty winds in advance of it Friday
afternoon/evening, but especially Saturday afternoon and evening.
The trough won`t completely lift out of the area Monday, but
heights will rise a little, so temperatures should get back
closer to normal. The models maintain an upper trough over the
Pacific Northwest next week with a series of shortwaves moving
through. None of these is particularly strong, so precipitation
chances will remain low, but any attempt at warming should be
thwarted with the arrival of each disturbance.
FIRE WEATHER...Updated 200 PM PDT Thursday 13 September 2018...
The main fire weather concern in the near term is gusty winds and
low humidities east of the Cascades Friday afternoon and evening and
again Saturday afternoon and evening. These winds will be associated
with a front that will move onshore this weekend. Saturday will be
the windier day. Conditions will approach, but are not expected to
meet, Red Flag Warning criteria over Lake and Modoc counties. The
front will bring some precipitation to the area, mostly from the
Cascades west and Siskiyous north, but not season-ending rains.
Beyond Saturday, the next concern is possible gusty east winds over
the ridges of southwest Oregon Monday night, which may lead to
moderate RH recoveries.
OR...Freeze Watch from late Friday night through Saturday morning for
Freeze Warning from 3 AM to 9 AM PDT Friday for ORZ029>031.
CA...Freeze Watch from late Friday night through Saturday morning for
Freeze Warning from 3 AM to 9 AM PDT Friday for CAZ084-085.
Pacific Coastal Waters...None.