Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/11/17
Area Forecast Discussion
National Weather Service Caribou ME
953 PM EST Sun Dec 10 2017
.SYNOPSIS...
Weak low pressure will approach from the west tonight and then
move east Monday. High pressure will build across the region
Monday night. Strong low pressure will lift across the region
later Tuesday through early Wednesday.
&&
.NEAR TERM /THROUGH MONDAY/...
935 PM Update: Larger scale models indicate a sfc wv of low pres
crossing from NW to SE ME across a stalled arctic front that
just recently entered Nrn ME this eve, very late tngt into Mon,
with latest HRRR sim radar ref showing an intially band of sn
shwrs with this sfc wv affecting Nrn ptns of the FA in addition
to lgt mixed precip/sn alg the Downeast coast very late tngt
and erly/mid mon morn. Therefore, we added chc PoPs to Nrn ptns
of the FA for the late ngt into the Mon morn tm frame alg with
associated lgt 6hrly QPFs/snfls. Otherwise, fcst hrly
temps/dwpts were updated thru the late ngt hrs based on trends
from latest sfc obs, with not enough deviation from the prior
fcst update to make any chgs to fcst ovrngt lows attm.
Orgnl Disc: The low pressure system that brought the first
measurable snowfall to much of the region last night has moved
well east of the Canadian Maritimes. A westerly flow of drier
air has moved into the area in the wake of the low. Our
attention now turns to an arctic frontal boundary just to the
northwest of the state. Behind the boundary, temperatures this
afternoon were only in the single digits above zero to lower
teens across much of Quebec province. This boundary will begin
to cross northern portions of the region tonight. An upper
disturbance will also cross northern areas through early this
evening with a chance of snow showers, and even a brief snow
squall mainly across far northern areas and the St. John Valley.
We should then see a brief break in any snow shower activity
through the first half of the night. However, a weak area of low
pressure across southern Quebec is expected to track east along
the boundary and across far northern Maine toward daybreak on
Monday. This will result in another chance for snow showers
after midnight, mainly across northern and western areas. In
addition, another weak area of low pressure is expected to
develop along the down east coast as short wave energy rotates
east around the upper trof. This low is expected to move quickly
east into the Canadian Maritimes early Monday. Near term models
are keeping the bulk of the moisture with this feature just
offshore and to our east. However, it looks like the immediate
down east coast could see a brief period of light snow with this
system after midnight into early Monday morning. Precipitation
amounts look to be light, less than a tenth of an inch, so any
snow accumulation looks to be an inch or less. Brought the
western edge of likely pops(60%) just into the immediate down
east coast late tonight into early Monday morning. Otherwise,
any morning snow showers across the north and light snow along
the down east coast will give way to at least partly sunny
conditions, with perhaps a few lingering afternoon flurries by
afternoon. Lows tonight will range from the single digits above
zero across the St. John Valley to the upper teens to around 20
down east. Highs on Monday will range from the mid teens to
around 20 north and upper 20s to lower 30s Downeast.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
High pressure will exit to the east Monday night while
intensifying low pressure tracks across the eastern Great Lakes.
Cloud cover will increase across the region Monday night. The
low will track toward southern Maine Tuesday. Snow will expand
northeast across the region Tuesday. Onshore winds will draw
warmer air toward the Downeast coast during the afternoon,
which could allow the snow to mix with rain or transition to
rain during the afternoon into the evening. The low will lift
northeast across Maine Tuesday night, though the exact track is
still uncertain. Snow will persist across northern areas Tuesday
night. However, dependent on the track, warmer air being drawn
north could allow the snow to transition to a wintry mix
particularly across eastern areas. Snow, or a wintry mix, early
Tuesday night Downeast will taper to snow showers overnight.
Have issued a Winter Storm Watch for most of the forecast area,
with the exception of the Downeast coast, Tuesday morning into
Wednesday morning. The heaviest snow totals are expected across
northern Aroostook county, where amounts in excess of 8 inches
are possible. Lesser snow accumulations are expected southward
across the remainder of the forecast area, dependent on the
eventual track of the low. The least snow is expected along the
Downeast coast where the snow should transition to rain or mix
with rain. The surface low lifts toward the Gulf of Saint
Lawrence Wednesday while the upper low crosses the region.
Deformation zone snow or snow showers will persist across the
north and mountains Wednesday with the upper low and wrap around
moisture from the surface low. Mostly cloudy skies along with a
chance of snow showers are expected Downeast Wednesday.
Temperatures will be at below normal levels Tuesday, with
slightly below normal level temperatures Wednesday.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Could still have a chance of snow showers across the north and
mountains Wednesday night, with decreasing clouds Downeast. High
pressure will build across the region Thursday. Low pressure
should intensify east of the region Friday. Dependent on the
track of the low, the western edge of the precipitation shield
could bring a chance of snow to the region. High pressure is
expected Saturday. Low pressure should approach from the west
Sunday with a chance of snow. Temperatures will be at below
normal levels Thursday through Sunday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions to start the evening but we could see
brief MVFR/IFR conditions developing this evening in any sct
snow showers activity associated with an approaching frontal
boundary. Mainly VFR on Monday but again could see briefly lower
conditions in scatterd snow showers, mainly north.
SHORT TERM: VFR conditions are expected Monday night. Conditions
will lower to IFR/LIFR levels across the region Tuesday morning
through the afternoon. IFR/LIFR conditions are then expected
Tuesday night into Wednesday morning. Occasional MVFR
conditions will then persist Wednesday afternoon. Occasional
MVFR conditions will persist across the north and mountains
Wednesday night into Thursday. Occasional MVFR conditions are
possible Downeast early Wednesday night, with VFR conditions
overnight into Thursday. Conditions Friday will be dependent on
the eventual track of low pressure and whether snow is wrapped
back across the forecast area.
&&
.MARINE...
NEAR TERM: A small craft advisory is in effect through early
Monday morning. Small craft advisory may be needed into Monday.
SHORT TERM: Small craft advisory conditions are expected Monday
night into Wednesday. Visibilities will be reduced in rain and
snow Tuesday morning into Wednesday morning.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Watch from Tuesday morning through Wednesday
morning for MEZ001>006-010-011-015>017-031-032.
MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ050>052.
&&
$$
Near Term...VJN
Short Term...Norcross
Long Term...Norcross
Aviation...VJN/Norcross
Marine...VJN/Norcross
Area Forecast Discussion
National Weather Service Dodge City KS
500 PM CST Sun Dec 10 2017
...Updated Aviation...
.SHORT TERM...(This evening through Monday)
Issued at 248 PM CST Sun Dec 10 2017
Water vapor loop and RAP analysis revealed pronounced mid-upper
tropospheric anticyclone across the western CONUS with ridge poking
north well into British Columbia. Rounding the ridge was a shortwave
trough diving southeast into Montana. This feature will continue to
roll southeast tonight, with a surface low pushing southeast from
the eastern Dakotas into northern Illinois by midday Monday. The
primary jet streak tied to this feature will remain northeast of
western Kansas, and as a result, the coldest air will remain
northeast of western Kansas. We will see the wind, though, like we
usually do with these types of systems. After a period of mainly
westerly light winds tonight (10 mph or less), winds will shift
gradually to the northwest and increase in speed by late morning.
Expect sustained winds on the order of 20 to 25 mph during the day,
perhaps stronger up around Hays. Gusts should be in the 30 to 35 mph
range. Cold advection will be muted by downslope warming, such that
afternoon temperatures should still reach 59 to 64F across much of
the southwest Kansas region.
.LONG TERM...(Monday night through Sunday)
Issued at 248 PM CST Sun Dec 10 2017
The hemispheric Pacific-North America (PNA) pattern, characterized by
mean ridge in the western CONUS and mean trough in the eastern CONUS
will continue through late Wednesday/Thursday, before the western
ridge finally breaks down. One last northwest flow, dry cold frontal
passage will occur late Wednesday/Wednesday Night with a fresh round
of cooler, but downslope-modified air. This front will be a bit
stronger than Monday`s front, which should result in highs Thursday
in the upper 40s to around 50 most locations. It will remain dry,
however. The hemispheric pattern will become more zonal in nature by
the upcoming weekend, with the main polar jet core remaining north
of western Kansas. This should result in a continued above normal to
perhaps well-above normal temperature scenario. There are some hints
that ridge-amplification will occur once again in the far extended,
but quite a bit farther west off the west coast of North American,
which could lead to deepening mean trough out west after about 20
December.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 500 PM CST Sun Dec 10 2017
VFR/SKC through Monday. Light west winds overnight will veer NW by
sunrise. Strong NW winds are expected at all airports after 15z
Monday, averaging 20-30 kts.
&&
.FIRE WEATHER...
Issued at 334 PM CST Sun Dec 10 2017
Near-critical to critical fire weather conditions are expected to
develop Monday late morning through afternoon as a very dry cold
front pushes south across western Kansas. Temperatures will not drop
much over what was seen today, with about the same dewpoint
temperature. The result should be at least a couple hours of around
15 percent relative humidity. Given the much stronger northwest
winds, a fire weather headline will be needed. After coordination
with surrounding WFOs, will issue a Red Flag Warning for Dighton-
Jetmore-Bucklin-Coldwater line and points west (matching well with
WFO GLD, PUB, AMA, OUN). East of this line, where there is greater
uncertainty in the 15-percent RH requirement being met, will issue a
Fire Weather Watch, which matches well against WFO GLD, GID, ICT,
and OUN.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 31 61 23 58 / 0 0 0 0
GCK 26 59 22 59 / 0 0 0 0
EHA 31 62 26 61 / 0 0 0 0
LBL 27 63 23 60 / 0 0 0 0
HYS 31 57 25 56 / 0 0 0 0
P28 32 63 26 56 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Monday morning through Monday afternoon
for KSZ030-031-045-046-065-066-079>081-090.
Red Flag Warning from 11 AM CST /10 AM MST/ to 6 PM CST /5 PM
MST/ Monday for KSZ043-044-061>064-074>078-084>089.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner
FIRE WEATHER...Umscheid
Area Forecast Discussion
National Weather Service Wilmington NC
1013 PM EST Sun Dec 10 2017
.SYNOPSIS...
Dry weather will continue with a return toward normal
temperatures into Tuesday. Another cold blast will arrive
Tuesday night into Wednesday as a strong dry cold front moves
through. Arctic air mass over the Carolinas on Wednesday will
warm back up Thursday through Friday. Another frontal system
will increase rain chances on Friday followed by a brief cool
down on Saturday.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 915 PM Sunday...Mainly an hourly temp/dewpt forecast for
the overnight period into daylight Mon. Used latest sfc obs and
their trends and meshed it with a consensus of the near term
models, HRRR, RAP and the HiReswrf. Majority of the ILM CWA will
experience lows at or below 32 degrees with some mid to upper
20s across the usual cold prone locations. Ecellent rad cooling
conditions tonight, with the sfc based inversion developing
this evening and persisting overnight. Winds will decouple with
some sites already under the spell of the decent rad cooling.
Some WAA occures aloft, mainly just above the sfc based
inversion thru 850 mb. The 1000-850mb progged thickness and
850mb temps themselves illustrate the overnight milder trend.
However this WAA will remain aloft due to the dense cold air at
the sfc.
Previous.....................................................
As of 300 PM Sunday...High pressure will control area weather
through Monday resulting in mainly clear skies through the period.
Temperatures will be below normal with lows in the upper 20s to
lower 30s tonight and highs Monday in the 50 to 55 degree range.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Seasonable start to the period will
be followed by another cold blast late Tues into Tues night as
a strong dry cold front moves through. As the next shortwave
digs down into the Southeast on Tuesday, it will push a strong
cold front through the Carolinas. Ahead of this front winds will
back to the SW and increase as gradient tightens. This
relatively warmer and moister flow will allow overnight temps
Mon night to remain up in the mid 30s to around 40.
Winds will begin to veer to a more westerly direction as cold
front approaches on Tues. This will initially bring temps up
into the mid 50s to near 60 for high temps on Tues, but there
will be an increase in clouds through the day as cold front
moves through, followed by deep cold and dry air heading into
Tues night as shortwave clears the coast. Overall, expect temps
to plummet late Tues into early Wed as 850 temps take a nose
dive from up near 8c early Tues down to -11c by daybreak on Wed.
A clear start Mon night will be followed by some clouds as
front moves through Tues aftn into early eve and then very dry
air will move in with dewpoint temps dropping down into the
teens by Wed morning. This arctic blast will feel even colder
when you combine the gusty NW winds early Wed making temps in
the mid to upper 20s feel as if they are closer to 20 degrees.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 PM Sunday...The extended will feature primarily a
continuation of below normal temperatures as anomalous ridge
across the western CONUS drives deep troughing over the eastern
half of the country. This trough will be re-enforced no less
than 3 times, Tuesday night just before the extended, Friday,
and again late Sunday, as 3 potent shortwave dig through the
longwave trough and cause a surge of cold air to envelop the
Carolinas. Each of these shortwaves will be accompanied by a
cold front, but for the most part these will be dry. However,
the front next weekend could be preceded by enough moist
advection that showers will be possible. The ECM is much
different from the GFS/CMC next wknd as it does not produce this
third shortwave or cold front for Sunday. Despite the pattern
being amplified, mid-level flow remains fast, so it seems likely
another shortwave cold front would be in the vicinity by the
end of the period and will lean the forecast in that direction,
but much uncertainty exists by D7.
Temperatures behind the cold fronts, Wednesday and
Friday, will be well below normal, with Wednesday highs likely
peaking in the low 40s. Weak warm advection does occur after
each FROPA, so Thursday/Friday, and likely again on Sunday, will
have temperatures more towards climo norms.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
As of 00Z...Could make an argument for one line TAFs. High
pressure centered to our southwest will give us light mainly
westerly flow through the forecast period. Moisture profiles do
not support fog, however some shallow ground fog is possible in
the usually prone areas. VFR Monday.
Extended Outlook...VFR.
&&
.MARINE...
NEAR TERM /THROUGH MONDAY/...
As of 930 PM Sunday...Mariner favored winds and sea conditions
tonight into Mon. The sfc pg will continue it`s temporary
relaxing phase overnight into Mon with winds becoming WSW to WNW
at 10 to occasionally 15 kt. The hier end of the wind fcst, 15
kt, will occur over SSTs in the 60s and hier as seen with
various Buoy reports. Significant seas will run 2 to 3 ft with a
7 to 9 second period pseudo Easterly ground swell dominating at
times.
Previous......................................................
As of 300 PM Sunday...Expect W to SW winds of 10 to 15 KT
through the period with seas of 2 to 3 feet. No flags required.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Southwest winds will increase Mon night
into Tues ahead of an approaching strong cold front. Winds will
veer to the west to northwest through Tues remaining up to 15 to
20 kts. As cold front passes across the waters late Tues, winds
will veer to the NW allowing a blast of very cold and dry air
to move in. Expect seas to reach into SCA thresholds by Tues
aftn and should remain up to 5 to 7 ft in increasing off shore
flow and plenty of CAA through late Tues into early Wed. The
increasing off shore flow will keep highest seas in the outer
waters Tues night.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Sunday...Gusty NW winds greet the period behind a
cold front which will be offshore Wednesday morning. Seas will
be falling thanks to the offshore flow, but wind speeds of 20-25
kts early Wednesday may necessitate an SCA carryover from
Tuesday. High pressure will build across the waters the latter
half of Wednesday and Thursday, allowing winds to ease to 10-15
kts while maintaining a W/NW direction. Seas will fall in tandem
during this timeframe, becoming around 2 ft after briefing
touching 3-5 ft Wednesday morning. Another cold front will
approach during Friday, and ahead of this feature winds become
W/SW and increase again to 15-20 kts driving seas up to 4-6 ft,
and another SCA may be required near the end of the week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...RAN
NEAR TERM...DCH/RAN
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...DL
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
530 PM CST Sun Dec 10 2017
.SHORT TERM...(This evening through Monday)
Issued at 322 PM CST Sun Dec 10 2017
A classic Alberta Clipper system will dive southeast across the
central and northern plains tonight into Monday. The surface low and
associated steadier snow will track southeast across Minnesota to
northern Illinois. Meanwhile the PV anomaly and cold pool aloft will
dive south across the Dakotas into Nebraska.
Strong winds are the main concern across our area on Monday, with
perhaps a few snow showers due to the cold air aloft. NAM and RAP
500 meter wind speeds indicate the potential for sustained speeds
around 30 mph during the late morning into the afternoon hours. RAP
is suggesting gusts could approach high wind warning criteria, and
this is not out of the realm of possibility with the PV anomaly
aiding in vertically mixing the stronger winds aloft to the surface.
Of note, the wind speed at 700mb is near 80 kts.
High temperatures will likely be reached late morning across
northern Nebraska, in the lower to mid 40s, then slowly fall as CAA
develops during the afternoon hours. Lower 50s are expected across
the sunnier areas across southwest Nebraska. In addition CAA will be
weaker in the southwest.
.LONG TERM...(Monday night through Sunday)
Issued at 322 PM CST Sun Dec 10 2017
Rain or snow chances are confined to Friday night and Saturday and
this is an artifact of last night`s model runs. POPs are limited to
20-30 percent for this forecast. There models were showing what
appears a frontal band of snow will move in from the west across
Nwrn and Ncntl Neb. That snow band has vanished in this mornings
model runs.
Another fairly strong cold front moves through Wednesday but, at
this time, it would appear to be weaker than the front Monday. 45-
65kt winds are indicated by all models in the 850-700mb layer but
500m AGL winds increase to 25-30 kt or 25-30 mph at the sfc. The
forecast uses consensus model output statistics for winds 20-25 mph.
Later forecasts will likely increase speeds if the strong winds
aloft continue to be shown by the models.
The temperature forecast uses the model blend plus the previous
forecast plus bias corrected guidance for highs in the 40s and 50s.
Bias correction tended to raise high temperatures a couple of
degrees and lower mins a couple of degrees.
None of the models indicate any kind of direct arctic air moving
into ncntl and wrn Neb. Thursday will be the coolest day; after the
cold front Wednesday, highs rise into the lower 40s in most areas
and this is still above normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 515 PM CST Sun Dec 10 2017
A cold front will move across western Nebraska early Monday
morning with winds being the main concern for aviation. Strongest
northwest winds will begin between KVTN and KONL along with some
light rain and snow mixed Monday morning. Strong northwest winds
will spread over all of western Nebraska through the day on
Monday.
&&
.FIRE WEATHER...
Issued at 322 PM CST Sun Dec 10 2017
The best guess on temperatures, wind and relative humidity across
the Frenchman basin Monday gives humidity less than 20 percent for
two hours. Given the strong winds forecast Monday, 30-45 mph, a 20
percent criteria for Red Flag conditions can be used, but still the
3 hour criteria isn`t reached. So a brief period of critical fire
danger is expected Monday afternoon which will be handled using the
traditional special statement. It is still possible later forecasts
could necessitate a Red Flag warning. The rest of Western and North
Central Nebraska is expected to experience strong winds but higher
relative humidity.
Frenchman basin and perhaps other parts of Southwest Nebraska will
continue to experience low humidity Tuesday and Friday. Light winds
are expected those days.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Taylor
LONG TERM...CDC
AVIATION...Power
FIRE WEATHER...CDC