Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/28/17
Area Forecast Discussion
National Weather Service Grand Forks ND
705 PM CST Mon Nov 27 2017
.UPDATE...
Issued at 659 PM CST Mon Nov 27 2017
Band of light rain showers, mostly sprinkles, continue to move
east but drying up some. Very light rain, sprinkles did occur in
Langdon and at 01z occurring in Cavalier ND into Winnipeg area.
Will maintain the low end chc pops into the evening but as prev
fcst had the chances dwindle late evening/overnight. West wind
shift passing into NW MN attm... Pretty good winds aloft tonight
with 40 kts at 925 mb in the 09z-12z period but inversion will
keep that from reaching the sfc. But enough of a breeze to keep
temps up. Coordination with surrounding offices yielded an update
for higher wind speeds/gusts for Tuesday. Close to advisory range
but appears a brief period of this psbl midday before gradient
weakens as high pressure moves in toward 00z Wed.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 326 PM CST Mon Nov 27 2017
Precip chances tonight and temperatures throughout the period will
be the main issues for the short term.
Upper trough over Saskatchewan will move eastward into
Manitoba/Ontario tonight, pushing the surface trough axis
currently entering the Red River Valley off into MN. Winds will
shift to the northwest behind the trough, with a weak cool front
behind the system. There is a band of decent radar returns
currently across northwestern ND in the area of good 700mb
frontogenesis. Not a huge amount reaching the ground, but enough
to continue with POPs across our north this evening. The GFS
continues to be the most bullish on QPF amounts, although the
latest RAP runs also have a fair amount. The NAM doesn`t have much
QPF for our area, but seems to be an outlier at this point. Bumped
up POPs just a bit, but do not think much more than a hundredth or
two will reach the ground. The precip will be fast moving, and
think it should move past our area by the time temps fall below
the mid 30s. Thus, will keep temps as rain as it exits the area by
late evening.
Weak cold air advection tonight, but there will be plenty of cloud
cover and northwest to west winds will keep the boundary layer
well mixed. Lows should drop down into the upper 20s to low 30s.
A cooler air mass than today will remain in place for tomorrow,
but think there will be less cloud cover and expect readings to
remain above seasonal averages. Highs should range from the low
30s near the Canadian border to the low 40s in the south. Winds
will decrease Tuesday night and should allow temps to drop into
the teens and 20s.
.LONG TERM...(Wednesday through Monday)
Issued at 326 PM CST Mon Nov 27 2017
Upper air pattern was quite progressive. Short wave trough over the
eastern Pacific will move through the Northern Plains on Wed
afternoon/Wed night and bring some light rain or snow. Upper level
jet is expected to be on the south and east sides of the trough.
Flat upper level ridge follow in tow Thu. The ridge is forecast to
extend from from the Northern plains to the eastern Pacific. Split
flow to be across North America with northern stream over the
northern states and southern stream over the southern states on Thu.
Fri through Mon
Zonal long wave pattern becomes more amplified through the period.
Long wave pattern becomes split over North America.
Flow aloft remains quite zonal Fri but begins to amplify Sat/Sun.
Weak short wave to move through Fri with little or no precip
expected. Models in reasonable agreement through Sat. Then the GFS
becomes a progressively faster solution over the ECMWF after Sat.
Both the ECMWF and the GFS were trending a little slower than
previous runs...the GFS less so. Will blend the models.
High temperatures were increased about a degree for Fri, Sat and Sun
and decreased one to three degrees for Mon from yesterdays
forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 659 PM CST Mon Nov 27 2017
Broken mid/high clouds along the frontal zone moving thru the
area. Skies clearing out from the west late tonight into Tuesday.
Exception is some stratocu which may move south into parts of NW
MN Tuesday. Winds will be gusty from the west in the 15-30 kt
range. Higher gusts psbl.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...JR
LONG TERM...JH
AVIATION...Riddle
Area Forecast Discussion
National Weather Service New Orleans LA
251 PM CST Mon Nov 27 2017
.SHORT TERM...
Rather benign weather regime to continue through Tuesday though
humidity will be on the rise into Wednesday. This resurgence of
moisture will allow the possibility of radiational fog to develop,
particularly in valley drainage prone areas before daybreak.
Short-wave feature races from the four corners region through
about Memphis TN area Tue night and Wednesday to bring a weak
surface boundary into the forecast area Wednesday, but devoid of
cold air advection. Better frontogenetic forcing takes place
farther north in the mid and upper Mississippi Valley Wednesday
night to drive a surge of colder high pressure southward under
trough amplification aloft. The best chance of rain in a long time
Wednesday ahead of the front but even this is only worthy of about
30-40 percent mention at this time. RR
.LONG TERM...
Continental cool and dry air remains in place into the weekend
with some onset of return flow during the day Sunday. This will
set the stage for a rather lengthy dwell time of gulf moisture
return ahead of what could be a substantial autumn storm middle of
next week. 24/RR
&&
.AVIATION...
VFR conditions will continue through the forecast.
Not anticipating any real issues but can not rule out tempo vis
restrictions at MCB and ASD. VFR conditions expected tomorrow and
then tomorrow night and into Wednesday we may start to see more
reductions in vis and lowered cigs. /CAB/
&&
.MARINE...
High pressure will continue to slide to the east and with
that easterly winds will continue to take over across the coastal
waters. Shower activity will slowly begin to increase tomorrow and
more so Wednesday. Onshore flow will finally back around to offshore
again by Thursday night and Friday as a front slowly pushes through.
This may be short lived though as southeasterly winds will return by
Sunday night. /CAB/
&&
.DECISION SUPPORT...
DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby tropical
events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.Radar...
This is a reminder that the KLIX WSR-88D radar will be out of
service beginning tomorrow, Tuesday, Nov 28, through Saturday, Dec
2nd for scheduled maintenance. Users are encouraged to use
surrounding radar sites KMOB, KLCH, KDGX and New Orleans Terminal
Doppler Radar TMSY during this outage.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 41 72 55 72 / 0 0 10 10
BTR 42 72 58 75 / 0 0 10 20
ASD 43 72 59 74 / 0 0 10 20
MSY 50 73 62 75 / 0 0 10 30
GPT 46 70 59 72 / 0 0 10 10
PQL 41 72 56 74 / 0 10 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
24/RR
Area Forecast Discussion
National Weather Service Portland OR
152 PM PST Mon Nov 27 2017
.SYNOPSIS...A few showers will linger today across southwestern
Washington and northwestern Oregon. Rain returns in earnest Tuesday
with a break Wednesday before the rainy pattern continues.
&&
.SHORT TERM...Tonight through Thursday...Radar shows isolated showers
continue this afternoon in terrain of the Coast Range and Cascades as
well as in the Willamette Valley from about Salem northward. Expect
these showers to dissipate this evening with the loss of daytime
heating as an upper trough continues to moves off to the east.
The next system is forecast to approach the coast late tonight with
rain spreading inland during the day Tuesday. Snow levels will start
out in the 4000 to 5000 ft range Tuesday morning, falling to around
3000 ft Tuesday night. Expect about 3 to 6 inches of snow in the
Cascades, not enough to create many impacts, but there will be snow
on the passes.
Rain turns to showers behind Tuesday`s front before a brief dry
period Wednesday and Wednesday night for most areas as weak high
pressure builds. The exception will be the Cascades, where light snow
may continue. If skies clear enough Wednesday night in the valley,
could see some fog again, similar to this morning.
Another trough pushes high pressure east on Thursday and brings a
return to rain. Snow levels increase ahead of Thursday`s system and
will be around 4500 to 5500 ft as precipitation starts. With PWAT of
generally less than an inch and boundary layer winds not much more
than 30 kt even at the coast, not seeing any significant threats with
this system from rain, snow, or wind. Bowen
.LONG TERM...Thursday night through Monday...The progressive weather
pattern will persist for much of the long term period as a series of
frontal systems move across the forecast area. Expect conditions to
remain somewhat showery Thursday night and Friday morning as models
depict Thursday`s front stalling/dissipating over the region. Models
then show another, slightly stronger, frontal system moving across
the Pac NW late Friday which could bring a period of heavy rain. The
good news is that this front looks to move across the region fairly
quickly so not expecting a lot of impacts at the moment. Conditions
become showery on Saturday as the upper level trough moves across
the region, with snow levels falling to around 2000 ft by Saturday
night. This could create some travel concerns for the Cascades late
Saturday as snow levels lower, but exact impacts will be determined
by how much moisture is left for the system to tap into. Lingering
instability will keep a chance of showers going into Sunday, with
conditions starting to dry out by Sunday evening. The drying trend
looks to continue on Monday as upper level ridging builds into the
Pac NW. /64
&&
.AVIATION...Generally VFR over the region early this afternoon.
There are some stubborn pockets of IFR in the interior valleys
and some of this may not clear out. Expect increasing IFR or
worse once again for the interior valleys after about 03Z Tue,
especially at KEUG and KHIO. Precipitation reaches the coast
overnight with the potential for MVFR conditions to develop.
Interior TAF sites likely to cover a wide range of flight
conditions after 12Z. Light offshore low-level flow returns late
tonight, which should keep areas near the Columbia Gorge VFR
despite precipitation.
KPDX AND APPROACHES...Improvement to VFR occurred around 20Z.
Still areas of IFR in the Tualatin Valley and this will only get
worse after sunset. VFR holds at the terminal and eastern vicinity
through at least 14Z Tue. Precipitation develops around 14Z with
an increasing threat of MVFR conditions. Weishaar
&&
.MARINE...Weak high pressure over the waters today will dissipate
this evening. The next frontal system is expected overnight into
Tue. The 12Z NAM and GFS are a little weaker with the forecast
boundary layer wind speeds. Low-end gale force speeds likely for
PZZ250 and PZZ270 starting around 06Z Tue. Higher resolution
models, such as the RAP and HRRR indicate 25-30 kt boundary layer
speeds for the north waters 08Z Tue. Lesser speeds forecast for
PZZ255 and PZZ275. Have opted to go with a small craft advisory
for wind in PZZ255 and PZZ275 beginning 03Z Tue. The NAM and GFS
indicate a distinct frontal boundary moving through the waters
Tue morning for an abrupt wind shift.
High pres builds into the waters late Tue and Wednesday. Another
front looks to cross Wednesday night and Thursday. The GFS and
ECMWF show vast differences beginning Fri. The GFS would suggest
high-end small craft advisory speeds or possibly gales Sat, while
the ECMWF is much weaker. Will lean toward the ECMWF at this
time.
Seas have eased to around 9 ft this afternoon, but periods near
10 seconds are maintaining square sea conditions. Seas will
remain just under 10 ft through tonight, but dominant periods
will be such that square sea conditions prevail. Next issue is
the incoming significant swell expected to arrive Tuesday night.
The latest ENP guidance came in about 3-4 ft lower than
yesterday. Spectral guidance for buoy 029 now has a peak of 19
ft, compared to 23 ft from yesterday. Long periods of 18-19
seconds will result in the potential for high surf conditions.
Output from a local wave energy tool shows a value near 110 late
Tue night, with 100 being the benchmark for high surf conditions.
The leading edge of the large swell train is not expected to
reach offshore buoys such of 46036 until at least 12Z Tue, based
on the latest ENP run. Would like to wait until the leading edge
of this swell train reaches the far outer buoys before going with
a high surf advisory. Seas settle down late Wed, but remain in
the low to mid teens through the week. Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Gale Warning from 9 PM this evening to 9 AM PST Tuesday for
Coastal Waters from Cape Shoalwater WA to Cascade Head OR
out 60 NM.
Small Craft Advisory for hazardous seas until 9 PM PST this
evening for Coastal Waters from Cape Shoalwater WA to
Cascade Head OR out 60 NM.
Small Craft Advisory for winds from 7 PM this evening to 1 PM
PST Tuesday for Coastal Waters from Cascade Head OR to
Florence OR out 60 NM.
Small Craft Advisory for hazardous seas until 4 AM PST
Wednesday for Coastal Waters from Cascade Head OR to
Florence OR out 60 NM.
Small Craft Advisory for Rough Columbia River Bar until 2 PM
PST this afternoon.
Small Craft Advisory for Rough Columbia River Bar from 10 AM to
3 PM PST Tuesday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA, or forecast area.
Area Forecast Discussion
National Weather Service Topeka KS
513 PM CST Mon Nov 27 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Tuesday)
Issued at 324 PM CST Mon Nov 27 2017
It appears most locations have mixed up to about 900 mb, which has
resulted in temperatures reaching the lower to mid 70s. Winds are
generally out of the south and gusting up to 30 to 35 mph. minimum
relative humidities will range from the upper 20 to the lower 40
percent. Therefore the fire danger is extremely high through about 5
pm when temperatures begin to cool. A decent pressure gradient is
forecasted to remain in place this evening as a cold front
approaches from the northwest. This should keep the boundary layer
partially mixed so winds will remain gusty. The cold front enters
north central KS shortly after midnight. Near the front winds relax
so temperatures will cool into the mid 40s, while partial mixing
further east keeps temperatures in the 50s.
As the front moves into portions of northeast KS moisture advection
and cooling temperatures aloft will result in a stratus deck to
form. Models are forecasting reasonable frontogenesis along the
front in the lower levels, which coincides with this moisture, and
an elevated mixed layer aloft. Therefore drizzle seems like a
possibility late tomorrow morning and into the afternoon. An area of
subsidence behind the front could inhibit any drizzle. Persistent
cloud cover most of the day should keep temperatures in the 50s.
North of the front dry air advection and relatively deeper mixing
will allow those temperatures to approach 60. Relatively humidity is
expected to drop into the 20 percent range, while northerly winds
around 15 to 25 gust up to 30 mph. This should cause very high fire
danger in north central KS. During the day tomorrow a closed mid
level low will track over OK mainly in the evening and overnight.
Mid to upper level dynamics should provide increasing lift while
better moisture accompanies the trough axis. Prior to sunset it
appears there will not be sufficient saturation in the mid levels.
Not sure if the low level saturation will be deep enough for warm
rain processes so have kept drizzle as the main precip type.
.LONG TERM...(Tuesday night through Monday)
Issued at 324 PM CST Mon Nov 27 2017
By Tuesday night, the closed mid-level low and surface low will be
positioned over Oklahoma, with the associated cold front just
exiting the CWA. The surface low should slightly shift to the
northeast toward the Missouri/Arkansas border with wrap-around
precipitation extending into the forecast area. However, with
models continuing to trend further south with this advancing low,
have continued to trim PoPs across north central KS, with the best
chances for precipitation being generally along and south of I-70.
Precipitation chances will increase late Tuesday evening into the
overnight hours as the mid-levels gradually saturate. Northerly
winds behind the front and partly to mostly clear skies now likely
across far north central KS will support low temperatures plunging
into the low 30s in that area, with mid 30s to low 40s expected
elsewhere across the CWA. As a result, much of the precipitation
should stay in the form of rain, but cannot rule out a few
snowflakes mixing in as the system progresses eastward early
Wednesday morning. Once this precipitation exits the area Wednesday
morning, dry conditions are expected through the remainder of the
week and through the weekend as surface high pressure spreads into
the central U.S. behind the front and advances into the eastern U.S.
by Friday. Temperatures mid to late week will be closer to the
seasonal normals with highs in the 50s and lows in the 20s/30s, with
a gradual warm-up into the weekend as winds generally shift to the
southwest with the passing surface high pressure. Focus then shifts
to the mid-level trough that models show diving southward across the
western U.S. on Sunday, which could bring precipitation chances to
the area on Monday as the system advances into the central U.S.
However, there are very notable model differences in whether a
closed mid-level low develops or if it remains an open wave as it
progresses into the central U.S., so these discrepancies will
certainly impact the timing and tracking of this system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday)
Issued at 513 PM CST Mon Nov 27 2017
Two concerns for aviation this forecast, LLWS and MVFR CIGS. Am
not that confident in there being a sharp change in wind speed as
NAM and RAP forecast soundings keep the boundary layer mixed. And
directional sheer is maybe 20 degrees. This is supported by
objective MOS guidance that maintains surface wind gusts around
20KT through about 10Z once the prefrontal trough moves in.
However the low level jet will be strong. Since prev forecast has
it included, will keep it in there for now.
There is pretty good agreement in an MVFR CIG developing within
the prefrontal trough Tuesday morning. At this time, CIGS look to
be above 2KFT. Once the FROPA moves through, CIGS should improve
mid afternoon as dry air advection increases from the north.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Hennecke
AVIATION...Wolters