Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/26/16
Area Forecast Discussion
National Weather Service Bismarck ND
943 PM CST Fri Nov 25 2016
.UPDATE...
Issued at 931 PM CST Fri Nov 25 2016
The forecast was blended to observed trends through 03 UTC. Expect
mid to upper level cloud cover to slowly thin in coverage through
the late overnight into Saturday morning.
UPDATE Issued at 725 PM CST Fri Nov 25 2016
Per IR satellite trends through 01 UTC, increased cloud cover through
the overnight. As a result, overnight lows were also increased a
few degrees over the previous forecast.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 301 PM CST Fri Nov 25 2016
Mild and dry weather will continue through Saturday, though it
will be seasonably cold again tonight.
Broad 500 mb ridging will remain in control of the weather across
the region tonight and Saturday, though a weak mid-level shortwave
trough depicted as a shearing zone of positive vorticity advection
moving from eastern MT this afternoon and across ND tonight should
act to flatten the ridging. Even so, high-level clouds which have
largely been originating as a so-called "Chinook Arch" downstream
of the Northern Rocky Mountains may decrease behind the weak wave
by Saturday, and the 12 UTC model guidance is in good agreement on
warming at 850 mb, both favoring an even warmer day tomorrow. That
12 UTC multi-model consensus calls for 850 mb temperatures ranging
from +5 C at Rolla to +7 C along the Missouri River and +10 C over
far southwestern ND by late Saturday afternoon.
In general, we relied on the 12 UTC multi-model consensus fields
to construct the short term forecast. However, we did rely on the
colder edge of MOS-based guidance for low temperatures tonight in
respect to recent forecast biases and the observed boundary layer
drying that has occurred this afternoon (dewpoints are mainly 15
to 25 F as of 20 UTC). We also relied on the warmer edge of MOS
(and in particular 12 UTC GFS-based MOS) for high temperatures on
Saturday in respect to largely snow-free ground and trends today.
However, light and mainly southerly surface flow on Saturday does
drive some uncertainty in how much mixing and warming may occur.
Finally, we did include patchy fog in the forecast tonight through
early Saturday morning over parts of McIntosh and Dickey Counties
from Ashley toward Ellendale. Visible satellite images reveal snow
on the ground in those areas, which is undergoing melting today,
and RAP and HRRR sounding profiles viewed in BUFKIT suggest low-
level turbulence will be small enough to support fog. Recent HRRR
iterations also simulate fog in those areas.
.LONG TERM...(Saturday night through Friday)
Issued at 301 PM CST Fri Nov 25 2016
The weather is forecast to be fine for post-holiday travel during
the day Sunday. However, accumulating snow, gusty winds and colder
weather is possible early next week. Snow potential will increase
as early as Sunday night and Monday morning with possible impacts
to the Monday morning commute, especially across central ND.
The 12 UTC deterministic and ensemble global model guidance stayed
the course showing a negatively-tilted upper-level trough ejecting
into the High Plains late Sunday before closing off aloft and then
slowly meandering across SD and MN Monday and Tuesday in response
to strong downstream blocking at 500 mb. Guidance even suggests a
temporary rex block may develop with a cut-off 500 mb high forming
across the Hudson Bay region early next week. This teleconnects to
a slow-moving trough and potential winter storm across the region.
The 12 UTC GFS and ECMWF continued to provide support for a very
deep surface low of 975-979 mb somewhere near the ND/SD/MN border
region by Monday morning as the deep cyclone becomes stacked. The
12 and 00 UTC NAEFS output forecast sea level pressure values at
the minimum for late November and early December, which is telling
both from the perspective of the sytem`s strength, and also with
regard to the ensemble support for its overall evolution. We feel
that the forecast timeframe may indeed have already moved inside
of the predictability horizon that`s dictated by initial-condition
sampling as the synoptic-scale wave placement is rather clustered.
That is not to say that uncertainty in details doesn`t exist, even
with the placement of the 500 mb low (the ECMWF is both slower and
further southwest than the GFS), but overall, confidence is
increasing with regard to potential accumulating snow beginning
Sunday night or early Monday.
The 12 UTC GFS, ECMWF, and NAM all supported a strong, 50 to 60 kt
low-level jet transporting seasonably-rich moisture poleward into
the region Sunday night with precipitable water values rising to
0.75 inches in eastern ND. Strong dynamic forcing associated with
the deepening trough will readily yield precipitation, though the
system will be relatively warm with the 850 mb 0 C isotherm and
thus a rain-snow line possibly lingering over east central ND and
the James River valley all the way into Monday. Synoptically, this
setup could favor a band of accumulating and possibly heavy, wet
snow west of that baroclinic zone, potentially over central ND. It
is too soon to write home on the details of that, but overall the
trend in the last 24 hours of model cycles has been to focus that
initial band of potential snowfall further west, and along the
Highway 83 corridor late Sunday night into Monday. Thereafter, as
the stacked low slowly meanders eastward through midweek we could
experience a prolonged period of lighter snowfall resulting from
persistent mid-level theta-E advection northwest of the cyclone.
It`s during that period, when large-scale moisture transport will
largely be cut off from the wave, that current model QPF output
could potentially end up being biased too high.
The 12 UTC GFS ensemble plume guidance continued to show a rather
large spread in liquid-equivalent moisture totals across the area,
but interestingly enough many members of the guidance are wetter
than the mean. Only a small set of the ensemble pack now suggests
little in the way of potential snowfall in central ND, especially
with the primary wave of moisture transport and forcing from late
Sunday night into early Monday.
Impacts will likely be felt from this round of winter weather, but
snow-to-liquid ratios will be relatively low given the relatively
warm nature of the system, and the resulting high-density snow may
not produce much blowing snow per the Baggely blowing snow model.
Moreover, road sub-surface temperature are near 40 F, which means
high snowfall rates will likely be required to yield accumulations
on road surfaces. This may overall limit the severity of impacts
to travel, but commerce may end up being more impacted because of
the recent stretch of very warm and dry weather that`s allowed for
outdoor projects to continue almost unchecked. True to that point,
through November 24th, this is Bismarck`s warmest November on
record, and we haven`t seen any snowfall of significance yet.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 931 PM CST Fri Nov 25 2016
VFR conditions are forecast for the 00 UTC TAF cycle across
western and central North Dakota.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...CJS
LONG TERM...CJS
AVIATION...AYD
Area Forecast Discussion
National Weather Service State College PA
1012 PM EST Fri Nov 25 2016
.SYNOPSIS...
A weakening cold front will cross the commonwealth overnight.
Colder air will arrive behind the front along with a gusty
northwest wind. Fair weather will accompany the arrival of high
pressure later Sunday through Monday, before a new frontal system
moves our way Tuesday through mid week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Latest sfc analysis shows frontal boundary over eastern
Pennsylvania late this evening. Radar shows area of pcpn moving
across western PA as rush of relatively colder air makes its way
across the mtns. Shortwave supporting the front looks fairly
potent on water vapor imagery. However sfc obs and latest HRRR
runs continue to support scattered and light nature to showers as
the move across mainly northern and hier elevations of central PA.
Pops will ramp up sharply over the Northwest Mountains as the
flow brings about an increase in lake effect. Expecting light
accums to commence by midnight with an inch or two possible by
morning over the normal snow belt areas of the NW and even a
coating possible in the upslope areas of the Laurels. This system
does not look to have the gusto of the recent storm that brought
several days of strong winds and an extended period of lake snows.
Lows tonight will drop back into the low to mid 30s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Cold NW flow will continue Saturday with additional light accums
of snow likely over the NW and Laurel Highlands, the normal spots
that see frequent snow showers in these flow patterns.
Highs Saturday will range from the mid to upper 30s northwest to
the upper 40s southeast. A gusty wind between 15-20 mph will make
it feel cooler.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Beginning of the long term will feature snow showers winding down
over the northwest zones. High pressure settles in Monday between
the departing system and a frontal boundary pushing east from the
midwest states.
By Tuesday...moisture streaming northeast from the lower
Mississippi valley will spread rain showers across the state.
While 850 temps surge above zero ahead of the precip...there may
be enough cold air near the surface for a mix of rain and non-rain
briefly at the onset.
The parent low...both at the surface and aloft...wobbles around
the upper midwest. This will allow a deep southwest flow to send
slugs of moistures toward the region through Thursday before
everything scoots to the east. Some residual lake effect snow
showers will fly in its wake by weeks end.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Ceilings are likely to come down a bit overnight, dipping to
IFR/LIFR at BFD and JST with scattered rain showers developing
and changing over to snow showers by daybreak. Central airfields
/AOO/UNV/IPT/ should see MVFR cigs overnight, while eastern
airfields /MDT/LNS/ dip to borderline MVFR/VFR cigs.
Slight improvement is expected for central and eastern terminals
on Saturday, with a downsloping northwesterly flow. As usual this
time of year, JST and BFD will suffer the effects of their
geography as moisture sweeps in off the Great Lakes and holds cigs
and vsbys borderline IFR/MVFR in scattered snow showers through
the day on Saturday. It will be breezy at all terminals.
High pressure will bring improvement to mainly VFR for all
central PA airfields by Sunday afternoon, and this will continue
into Monday. A round of rainfall will bring reductions Mon night
into Tues, with another shot of rain for Wed.
Outlook...
Sun...Restrictions possible N/W early in scattered snow showers.
Generally VFR elsewhere.
Mon...Mostly VFR. Deteriorating conditions with rain moving into
the west Mon night.
Tue-Wed...IFR/MVFR in rain and fog.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Gartner
NEAR TERM...La Corte/Gartner
SHORT TERM...La Corte/Gartner
LONG TERM...Tyburski
AVIATION...Evanego
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
641 PM EST Fri Nov 25 2016
.AVIATION...
Shortwave trough now digging southeastward across portions of NE IL
and the southern basin of Lake Michigan is driving an area of
midlevel saturation 800-700mb across much of southeastern Michigan.
Very subtle increase to cyclonic flow immediately in advance of
the vorticity maximum is providing slight theta e advection which
is resulting in an organized area of neutral stability in the 5.0
to 10.0 kft agl layer. Breaking it down forcing at the whole is
very weak to almost non-existent, relying on more favorable
thermodynamics. The lack of dynamics is supported by the
overwhelming surface observations with -ra but remaining at 7 to
10SM for vsby. With the back edge lining up to recent HRRR output
feeling is looking at shorter duration to rain activity this
evening, should end by 04-05Z. Surface dewpoints remain to warm
and precipitation rates remain too weak to support a changeover to
snow. Will be monitoring that this evening. No near surface dry
air advection will keep MVFR stratus to possible VFR stratus Sat
afternoon locked in place through the end of the period.
For DTW...Better subtle theta e advection thus far has remained
north of the Detroit metro area. Progs continue to support increased
near surface theta e and saturation pushing southward into DTW yet
this evening. delayed MVFR cigs and -RA until 01Z and should exit
the region by 03-04Z. Still could be looking at some potential
overnight for -DZ given degree of saturation in the lower
troposphere.
//DTW Threshold Probabilities...
* High for cigs aob 5kft.
* very low for ceilings aob 200 ft 00-04z.
&&
.PREV DISCUSSION...
Issued at 347 PM EST Fri Nov 25 2016
DISCUSSION...
The short term forecast is focused on the small but intense short
wave moving toward the south end of Lake Michigan late today and
over southern Lower Michigan during the evening. The system has a
much different look compared to yesterday`s projections in terms of
mesoscale structures, mainly in the strength of the circulation and
associated dynamic forcing. This will allow it to make the most of
the limited Pacific moisture supply and possibly even overachieve
with a boost of low level moisture and low level instability from
Lake Michigan. There are already signs the lake effect forcing will
couple with the mid levels of the circulation that is already
favorable for enhanced vertical motion. Mid afternoon satellite
observations indicate good texture in visible imagery and colder IR
enhancement over the north flank of the system which is
representative of enhanced vertical motion due to steeper mid level
lapse rates and deeper elevated instability. Synoptic and mesoscale
model solutions capture this in terms of convective instability in
theta-e cross sections centered around 700 mb with 700-500 mb lapse
rates in the 7.5 to 8 C/km range from 00Z-03Z this evening. This
will allow a good burst of vertical motion to develop as the larger
scale trough takes on more of a neutral tilt while the circulation
moves over SE Michigan. The resulting increased precipitation rate
will then open the door for at least a mix of rain and snow post
sunset as the freezing level drops below 1000 ft on the downside of
the diurnal cycle but with no more than a slushy coating on unpaved
surfaces. Likely POPs during the late afternoon through evening is
expected to represent the pattern well as it will be more of a
cellular convective pattern or possibly fragmented bands before
exiting west to east overnight.
High pressure is on track to build into the Great Lakes during
Saturday and low clouds continue to look stubborn prior to the
surface ridge passage. Satellite imagery today adds some confidence
to a more pessimistic cloud forecast through the day. This goes in
hand with colder afternoon temps just in time for the clearing trend
to begin during Saturday evening. Good radiational cooling will
likely take temps down into the 20s by Sunday morning, at the low
end or below guidance, as the sharp upper level ridge to our west
should guard against too much high cloud coverage. The rest of
Sunday will be a transition day as high pressure is driven
eastward by the large and strong low moving in from the west
coast. Southerly flow developing during the day will help boost
temps slightly above normal with the warming trend continuing
through Sunday night as clouds thicken over the region.
As low pressure over the Central Plains slowly approaches the Upper
Mississippi Valley region, deep southwesterly flow will set up over
Michigan bringing milder, wet conditions through midweek. With
shortwave energy ejecting towards the Great Lakes region Monday
night and favorable jet dynamics, large scale ascent will support
a broad area of rain Monday night. Drier conditions are expected
late Tuesday before another shortwave ejects northeastward towards
the Eastern Great Lakes bringing a chance of precipitation to
Southeast Michigan on Wednesday. As the low slowly moves eastward
across the Great Lakes region, westerly flow will setup keeping
unsettled conditions and seasonal temperatures in place through
Friday.
MARINE...
Moderate west to northwest will persist through the weekend bringing
a period of quieter marine conditions. Southeast wind will ramp up
early next week in advance of a large low pressure system over the
Upper Mississippi River Valley. Persistent southeast flow will
likely warrant small craft advisories for waves for the nearshore
zones during this time. There will also be a slight probability for
wind gusts to marginal gales by Tuesday.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....CB
DISCUSSION...BT/JD
MARINE.......DRC
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1039 PM EST Fri Nov 25 2016
.SYNOPSIS...
Warm and dry high pressure build into the region through the
weekend. Early next week, deep layer moisture will increase from the
west ahead of an approaching cold front with much needed rainfall
expected Tuesday and Wednesday. Cool high pressure returns Thursday
and Friday.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 10:23p EST Friday:
Temperatures behind the front edging across the area have been
slower to drop than earlier forecasts in some areas, and update
attempts to follow observed temperatures better. Fog is also of
diminishing concern with large dewpoint depressions and winds behind
the front likely to prevent all but a few very isolated areas of
fog through tomorrow.
An upper trough just west of the Appalachians will continue to
progress eastward and will be east of the CWA by Saturday afternoon.
A weak surface front associated with the upper trough is gradually
edging its way across western North and South Carolina. Eventual
passage of the front will reduce high temperatures on Saturday by 5
to 10 degrees below the near record highs seen on Friday. Passage
of the front will also veer the wind from southwesterly to
northwesterly with some wind gusts of 15 to 25 kts over the higher
terrain. Dewpoints will also drop behind the front about 10 degrees on
Saturday leading to minimum RH values in the mid 20s over piedmont
areas and upper 20s in the mountains.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 245 PM Friday: On Sunday, the center of high pressure will
slide across the forecast area as the axis of a mid level ridge
ripples across the southern Appalachians. This pattern will provide
dry and clear conditions across the CWA. A blend of guidance
indicates that high temperatures should range from the upper 50s
across the NC zones to the low 60s across the Lakelands.
On Monday, sfc high pressure slides over the Atlantic as a cold
front moves over the Mississippi River Valley. Return flow will
strengthen across the northern GA and the western Carolinas through
the day. In fact, H85 winds may reach 50 kts across extreme western
NC by 0z Tues. Deep gulf moisture should stream over the region late
in the day, resulting in increasing sky cover across the southern
Appalachians. I will keep PoPs below SCHC. High temperatures may
warm from Sunday by only one to two degrees.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 230 PM EST Friday...A large upper low is going to spin and
gradually wobble toward the east over the Upper Midwest to central
Quebec during the Medium Range. This will keep the CWFA within a
persistent deep-layer SWLY flow thru most of the period. Models
agree on this overall pattern, but disagree on the how deep a potent
shortwave will round the base of the upper circulation and cross the
CWFA.
At the surface, an occluded low will spin under the upper low over
MN Monday night thru Wednesday, bringing a trailing cold front
slowly east across the OH/TN valleys and into the CWFA by daybreak
Tuesday. This should bring a round of showers, with highest QPF and
PoPs along the SWLY upslope areas of the southern NC mountains and
NE GA mountains. The 12z ECMWF and CMC both show a pronounced lull
in precip during the day on Tuesday, before a second round crosses
the area Tuesday night thru Wednesday. The second round has the
potential to produce some heavy rainfall, as a wave ripples NE along
a stalled front and provides 40-50 kts of 850 mb SWLY flow out of
the Gulf. The rain should taper off Wednesday evening and dry
weather returns for Thursday and Friday. Storm total QPF from Monday
night thru Wednesday night could be range from 1-3" with 4-6"
possible along the SW-facing slopes of the NC/SC/GA mountains.
Confidence is high on rain chances (with likely to categorical
PoPs), but still some uncertainty on these QPF amounts. Temps will
be way above normal during the night with strong WAA and clouds and
precip. Max temps will be a couple categories above normal Tuesday
and Wednesday. Then as the front finally pushes east and some
continental air filters in temps will return to near normal.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
At KCLT: Weak surface trough/front will pass through the area
tonight and veer winds from southwesterly to northwesterly. Precise
timing is difficult due to diffuse nature of front, but a FROPA
around 0130Z is reasonable and close to the timing of the latest
HRRR run. Behind the front, 850mb winds to 25kts are expected to
lead to some gusty winds of 10 to 15kts Saturday afternoon with the
diurnal mixing.
Elsewhere: Surface front/trough will pass through the area tonight
and veer winds from the southwesterly to northwesterly. Behind the
front, 850mb winds to 25kts are expected to lead to gusty winds of
10 to 25kts Saturday afternoon with the diurnal mixing, with the
strongest gusts over higher terrain. At this time, KAVL is the only
TAF location that will have significant winds. Smoke has cleared
this evening at KAVL, but with on-going fires in the area, smoke may
return later tonight or tomorrow. KAVL also has a limited chance
for fog in the morning, though dry advection and winds should limit
fog.
Outlook: Drier high pressure returns for the weekend. The main
threat of restrictions through the period should be associated with
smoke plumes. More abundant rainfall, and associated restrictions,
looks increasingly likely this Tuesday/Wednesday.
Confidence Table...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL Med 63% Med 64% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.FIRE WEATHER...
A dry airmass will begin to spread across the region today, remaining
through the weekend and into early next week. A powerful mid level
wave will approach the region at that time. At the surface, a cold
front is expected to sweep in from the west, with prefrontal winds
increasing from the SE. This pattern should bring deep moisture from
the Gulf of Mexico. The combination of deep moisture, upslope flow,
and a large area of synoptic scale forcing indicates precipitation
may start as early as Monday afternoon over the mountains, with
widespread rain across the forecast area late Tuesday into
Wednesday. Guidance indicates that the potential exists for 1-4
inches of rain across the mtns and foothills.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...ARK
NEAR TERM...WJM
SHORT TERM...NED
LONG TERM...ARK
AVIATION...WJM
FIRE WEATHER...
Area Forecast Discussion
National Weather Service Lincoln IL
908 PM CST Fri Nov 25 2016
.UPDATE...
Issued at 907 PM CST Fri Nov 25 2016
Satellite images continue to show a steady eastward progression of
the back edge of the cloud mass. Clearing has reached as far east
as a line from Jacksonville to 10 miles east of Galesburg at
03z/9pm. Timing the current progression would put the majority of
our counties into mostly clear conditions by sunrise. HRRR and RAP
soundings are starting to catch up to that scenario, but still
lag by several hours. Have sped up the clearing in the sky grids
overnight.
Any clearing that develops will set the stage for fog formation.
Light winds and clear skies will allow temperatures to fall
quickly, dropping dewpoint depressions to 0-2F, due to an
elevated moisture content in the boundary layer. Will add some
patchy fog to areas west of I-55 for now, but that could expand
toward I-57 if clearing continues on its current pace.
Low temps may dip slightly below guidance numbers if skies clear
out sooner as well. We went with some upper 20s in the west, towards
Galesburg and Jacksonville, and kept 30-32 elsewhere. Updated
forecast info will be available shortly.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 236 PM CST Fri Nov 25 2016
Main question in the short term is the cloud trends tonight. Clouds
have been pretty persistent, but latest visible satellite imagery
and a check of area webcams indicates some thinning of the clouds is
taking place along the I-72 corridor and also just north and west of
Peoria. The western flank of the cloud shield also has made steady
eastward progress today. The midday run of the HRRR is doing a
reasonable job with the cloud edge, but largely keeps the CWA cloudy
past midnight aside from some breaks in the far southwest. As such,
will keep mostly cloudy conditions going through the night from
about Peoria-Flora eastward, with partly cloudy skies to the west by
mid evening. Despite the clouds, temperatures should be colder
overnight than this morning, as a surge of colder air drops in
behind the shortwave currently swinging through Wisconsin and
northern Illinois. Went with lows in the lower 30s over the entire
CWA, but some 20s are not out of the question across the west where
the skies clear out.
A ridge of high pressure will drift east across the Mississippi
Valley on Saturday, pushing out the remainder of the clouds as a
surge of milder air pushes eastward. Much of the CWA should reach
the lower 50s, coolest east of US-51 where the clouds will stick
around the first part of the day.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 236 PM CST Fri Nov 25 2016
Forecast models look quite similar at the beginning with the next
weather system, which is expected to bring precip to the CWA for the
latter part of the weekend and the first part of next week. As the
surface low pressure area moves out from the eastern Rockies and
into the northern plains tomorrow night, warm and moist air will
advect northward into the area Sunday morning. Precip is expected to
develop west and southwest of the area during the morning and then
spread into the western part of the CWA Sunday afternoon. Just
showers are expected since the best instability should be west of
the area, closer to the actual frontal system in the plains.
Showers should become more numerous and widespread over the area
Sunday night. The precip is expected to come in two waves with the
Sun night precip being the first wave. After a lull in the precip
Monday morning, the second wave will arrive in the area Monday
afternoon and continue through Monday evening, and be associated
with the main cold front that should push through the area Monday
night. Most of the models bring the heaviest precip associated with
the second wave across the eastern and southeastern part of the CWA,
while the NAM brings it northeast along I-55. Since this is the
first run of the NAM that does this, will maintain the trend of the
heaviest rain moving across eastern and southeastern IL Mon
afternoon through Mon evening, which this agrees well with HPC QPF
forecast. However, if other models trend back to west in later
forecast, do not be surprised to see an adjustment in that
direction. Throughout the whole CWA, from Sun night through Mon
night, QPF forecast looks to be around an inch with some areas
approaching 1.25 inches, mainly in the southeast and possibly along
the Illinois river. Not expecting any headlines at this time, but
brief heavy rainfall combined with clogged drains could create some
localized flooding Monday afternoon through Monday night. In
addition to the possible heavy rainfall, models forecasting some
minor instability in the area for Monday afternoon and evening, with
some elevated instability as well. So have added slight chance
thunder in for forecast for those two periods. However, it will not
get mentioned at this time in the worded forecast.
This precip associated with this weather system should push
northeast and east of the area quickly Monday night, resulting in
dry weather for Tue through Wed. Models then show some differences
again Wed afternoon and Wed night with the GFS showing dry weather
and the ECMWF and CMC showing another wave riding up the cold front,
bringing more precip to southeast IL. First time models are showing
this and with the differences, will just have slight chance of
precip during that time period in southeast IL...which will not be
mentioned in the worded forecast at this time. The remainder of the
week should then be dry as the flow becomes more zonal and the upper
level system sits over the Great Lakes region.
Temps will be quite warm, above normal, for Sunday and Monday, and
even into Tuesday. Then the cooler, more seasonable temps will
return after the system for Wed through Fri.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 547 PM CST Fri Nov 25 2016
Main issue remains with the progression of the clearing of MVFR
clouds. Satellite images show the back edge of the clouds
marching east, finally entering a small portion of far western IL
at 2330z/530pm. Forecast soundings and simulated satellite
imagery continue to show central Illinois remaining in the clouds
overnight, but clearing line on satellite seems to be maintaining
steady progression into Illinois. Will introduce some clearing at
PIA at 06z, and expand that eastward through Saturday morning.
Winds will remain westerly at 4-7kt the rest of tonight, then
become southwest after sunrise. Southwest wind speeds are
projected to increase to 10-14kt Saturday afternoon in response to
an intensifying warm advection flow aloft.
SHORT TERM...Geelhart
LONG TERM...Auten
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Auten
AVIATION...Shimon
Area Forecast Discussion
National Weather Service New York NY
933 PM EST Fri Nov 25 2016
.SYNOPSIS...
Coastal low pressure develops to the south tonight and passes
well southeast of Cape Cod on Saturday. This low intensifies and
tracks into the Canadian Maritimes on Sunday. High pressure builds
over the local area Sunday Night through Monday Night. A frontal
system approaches and affects the tri-state through mid-week. High
pressure builds in for the end of the week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Have removed likely Pops from the forecast overnight with just
high chance across Long Island and southeastern Connecticut. Light
rain should be spotty overall and do not expect coverage to be
widespread enough to support likely Pops. In the spotty light
rain, a few hundredths at most are expected. This is supported by
the new 00z 12-km NAM and 4-km NAM. The HRRR does not seem to be
initializing well as its reflectivity coverage is overdone
compared to actual radar.
Have added patchy fog tonight for outlying areas, but do not think
visibility will fall lower than 2-3SM where any fog does occur.
A PAC/northern stream shortwave complex over the Great Lakes
approaches tonight. The upper energy will swing into the
Northeast US tonight...with low pressure developing east of the
Delmarva. Models in good agreement on evolution of the upper
energy...and low pressure tracking well s and se of the region
tonight.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Fairly good model agreement with upper trough energy crossing
through the region Saturday...followed by northern stream closed low
sliding into New England Sat Night into Sun. This complex
eventually phases over the Canadian Maritimes Sun Night/Mon. With
this later phasing...offshore low pressure should take a track
well se/e of New England on Sat...rapidly intensifying as it
tracks into the Canadian Maritimes Sat Night/Sun.
In terms of sensible weather for the region...any lingering light
rain over far E LI/SE CT should push offshore Sat morning.
Otherwise...mostly cloudy...seasonably cool and increasingly breezy
conditions on Sat under the influence of cyclonic flow around the
developing offshore low. It appears we should be in between
shortwaves...so not expecting much in the way of instability
precip on Sat. Highs generally in the 40s interior and lower 50s
coast.
Reinforcing shot of caa late Sat Night into Sun morning as shortwave
energy rounds upper low and offshore low rapidly deepens. Perhaps a
few flurries depending on track of shortwave...otherwise breezy and
seasonably cold.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Tranquil conditions for the beginning of the long term as weak
surface high pressure builds in for Sunday and upper level trough
exits the East Coast. The center of high pressure moves over the
area Sunday night as upper level ridging over the Great Lakes region
moves slowly east toward the area. A northwest flow will bring in
seasonably cool air for this time of year through Monday. Highs on
Sunday will be in the lower to middle 40s, with slightly higher
readings for Monday. Conditions should be dry through this time
frame.
Thereafter, conditions look to be unsettled for the mid-week period
as the upper level ridge moves over the region Tuesday and then
passes east of the area Tuesday night, allowing a longwave upper
level trough to approach. Its associated surface warm front will
also approach the area from the southwest on Tuesday, followed
quickly by a cold front Tuesday night. This cold front looks to stay
just south of the area into Wednesday. Thereafter, there are some
differences in model solutions. The 12Z ECMWF develops a low along
the triple point that will be right over the area by 12Z Thursday,
while the 12Z GFS develops a smaller, weaker low near the area by
00Z Thursday.
Based on this agreement with some type of low developing in both
models, increased POPs to likely for Tuesday with the passage of the
warm and cold fronts, with a bit of a respite possible Tuesday night
into Wednesday, then likely again for Wednesday night as the low
pressure develops and moves over the region. There may be a period
of moderate to heavy rain at times during these time frames of likely
rain. However, there is still uncertainty in where, when and how
strong the developing low will be, but a widespread 1 to 2 inches of
rainfall across the area is not out of the question. With antecedent
dry conditions, no flooding is forecast, with the exception of
possibly some locally minor urban and poor drainage issues.
Thereafter, conditions will be dry through the end of the week with
high pressure building in.
Above normal temperatures return for Tuesday into Wednesday as warm
air advection gets underway. Thursday also looks to be seasonably
warm, with temperatures falling to seasonable levels again for
Friday.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Low pressure develops off the Mid Atlantic coast tonight, and
pass to the east on Saturday.
VFR at city terminals tonight with a small chance of MVFR
overnight. MVFR will likely continue at HPN and GON through the
night and may develop at ISP. MVFR at SWF should lift to VFR
around 06z. MVFR could linger into a portion of Saturday morning
across eastern Long Island and southeast Connecticut. Otherwise,
VFR is expected Saturday.
Light winds tonight should become NNW late tonight into daybreak
Saturday and begin to increase. NNW winds around 10 kt late Saturday
morning into the afternoon with some gusts 18-20 kt possible near
the coast in the afternoon.
.OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
.Saturday night-Monday...VFR.
.Tuesday-Wednesday...MVFR or lower conditions likely in rain.
S winds G15-20KT along the coast.
&&
.MARINE...
Sub sca conditions tonight into Sat with a weak pressure gradient
as low pressure develops off the DelMarVa and track well se of the
waters. NW winds gradually increase Sat into Sat Night as
the offshore low strengthens...with marginal SCA gusts possible
on the ocean late Sat night with accompanying shot of caa.
Marginal sca gusts possible through Sun Night.
Thereafter...Winds and waves remain below SCA criteria Monday
through the day Tuesday. Waves build on the ocean waters out ahead
an approaching frontal system Tuesday night. 5 to 8 ft waves are
possible Tuesday night. Waves may diminish somewhat on Wednesday
morning, but continue to build Wednesday afternoon into Wednesday
night , with 10 ft waves possible for the eastern ocean waters.
Waves slowly diminish Thursday, but remain above SCA criteria
through the end of the long term.
&&
.HYDROLOGY...
No widespread significant precipitation is expected through early
next week.
A prolonged rain event is forecast for the mid-week period.
Widespread rainfall amounts of 1-2 inches are possible, with locally
higher amounts. Antecedent dry conditions will preclude widespread
flooding. However, locally minor flooding for urban and poor
drainage areas are possible. There is still uncertainty with
rainfall amounts at this time due strength, placement, and timing of
low pressure.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JP/NV
NEAR TERM...JP/NV/DS
SHORT TERM...NV
LONG TERM...JP
AVIATION...DS
MARINE...JP/NV
HYDROLOGY...JP/NV
Area Forecast Discussion
National Weather Service Norman OK
925 PM CST Fri Nov 25 2016
.DISCUSSION...
Light winds and clear skies have led to the usual hodgepodge of
temperatures across our forecast area. The latest runs of the HRRR
model suggest lower chances of fog than previously expected, but
with temperatures nearing dew points across most of the Freezing
Fog Advisory area, it seems imprudent at this point to make any
changes to the advisory.
Have made some minor adjustments to hourly forecasts overnight to
account for the current conditions and short-range
expectations...mainly to temperatures/relative humidities over
the next few hours.
&&
.PREV DISCUSSION... /issued 510 PM CST Fri Nov 25 2016/
AVIATION...
Light winds tonight and clear skies will lead to the development of
some fog, especially across portions of central into north central
oklahoma. With temps falling below freezing some concern for some
dense freezing fog at PNC, so have introduced a tempo there.
Conditions expected to improve by 15Z with sites becoming VFR
through much of the day. Gusty south winds will develop across west
during the day with increase moisture creating MVFR ceilings late
across west/southwest sites.
30
PREV DISCUSSION... /ISSUED 218 PM CST Fri Nov 25 2016/
DISCUSSION...
Relatively benign weather expected tonight through Saturday night.
Winds will continue to decrease and become variable this
afternoon/evening as sfc high settles over the area. Sfc winds will
then shift to the south Saturday with some low level moisture
spreading back north Saturday into Sunday.
Models show several shortwaves affecting the region Sunday into the
first half of next week. The first shortwave will affect the area
Sunday. Meanwhile, a sfc low will deepen as well leading to a
strengthening pressure gradient across the area. This increasing
pressure gradient along with any mixing will likely lead to strong
southerly winds across the area Sunday. Clouds could limit the
mixing some but the pressure gradient could be enough that a wind
advisory would be needed for part of the area during part of the day
Sunday. If mixing, especially strong mixing, does occur, even
stronger winds could be possible due to the winds just off the sfc
with models showing 925mb winds 35-45 kts and 850mb winds 45-55 kts
across the area Sunday afternoon.
Wildfire conditions could also be a concern for NW/W parts of the fa
Sunday afternoon. With the strong winds, wildfires could be a
concern but humidity reaching critical levels is uncertain. Models
show a dryline possibly approaching/moving into parts of the fa
Sunday afternoon. If the dryline does move into the fa and/or enough
mixing occurs, then rh values could drop to critical levels.
However, some of the models keep the drier air just west of the fa
and humidities do not drop to critical levels. Either way elevated
wildfire conditions are expected but later shifts will need to
continue to monitor the model trends to see if any fire weather
headlines are needed.
In addition to the wind and wildfire concerns, showers and some
thunderstorms will be possible Sunday into Monday. The shortwave
Sunday and then another one Monday along with a cold front moving
across the region will likely produce enough lift for some showers
and storms. The highest chances will be in SE parts of the fa. Dry
air will move into the area behind the cold front which will make it
difficult for any precipitation to develop Monday night into Tuesday
when a third shortwave and another frontal boundary moves across the
region. The forecast will be dry through Thursday but another storm
system could bring another chance for precipitation to parts of the
area towards the end of next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 33 61 47 64 / 0 0 0 40
Hobart OK 34 59 49 67 / 0 0 10 40
Wichita Falls TX 37 62 49 69 / 0 0 0 20
Gage OK 32 64 48 68 / 0 0 0 40
Ponca City OK 31 62 45 64 / 0 0 0 50
Durant OK 38 63 46 66 / 0 0 0 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Freezing Fog Advisory from 2 AM to 9 AM CST Saturday for OKZ007-
008-012-013-020.
TX...None.
&&
$$
23/30
Area Forecast Discussion
National Weather Service Mount Holly NJ
840 PM EST Fri Nov 25 2016
.SYNOPSIS...
An area of developing low pressure just east of the Virginia Capes
will move out to sea overnight into Saturday. High pressure will
build in from the south and west this weekend. The high will begin
to shift offshore on Monday. A storm system is forecast to move
through the northern Plains and upper Midwest early next week. A
cold front with this system will progress toward the forecast area
by midweek. Meanwhile, a wave of low pressure may develop over the
Gulf Coast states Tuesday and then track northward along the front
through the eastern U.S. on Wednesday. High pressure builds in
from the Mid South late in the week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
At the surface, the region remains within a saddle point between
weather systems, the primary being a weak area of low pressure
developing east of the NC/VA border. This has maintained a light
and variable wind at the surface, and with plenty of low level
moisture in place, patchy fog has developed across portions of
northern NJ and northeast PA. As the low moves out to sea, well
southeast of the area overnight, the synoptic flow will become
more northwest. But with a low-level inversion and weak gradient
in place, do not expect much mixing until closer to dawn, so the
patchy fog should remain in place through much of the night,
especially at the more sheltered locations across the north.
The forecast was updated to reflect this.
In terms of precipitation, the 12Z model QPF fields were over
done in terms of the coverage of light precipitation across a
good part of the region. The 18Z GFS and recent RAP runs have
come into better line with the current trends, and also make
more sense given the synoptic pattern. A narrow band of rain
showers has developed near the I-95 corridor this evening, in
response to a vorticity streamer moving through the southwest
flow aloft. Given the moisture is relatively shallow and the
lift is weak, expect generally light amounts, at or below one-
tenth of an inch, before gradually diminishing after midnight.
A second area of precipitation was developing just offshore
in conjunction with the stronger lift (surface pressure falls)
associated with the aforementioned area of low pressure. The
model mass fields indicate stronger lift and deeper moisture
remaining just offshore, in addition to a low-level northerly
wind trajectory at the surface. This suggests the bulk of this
precip should remain offshore and forecast PoPs were adjusted
downward over land to reflect this.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
The surface low is forecast to strengthen as it moves farther out
to sea on Saturday. As a result, the northwest wind in our
region should increase to 10 to 15 MPH with gusts around 20 MPH.
A mid level short wave that was located over the upper Mississippi
River Valley this afternoon should pass over the northern part of
our forecast area on Saturday morning. The axis of the main mid
level trough is expected to arrive late in the day.
We are anticipating a fair amount of stratocumulus over our
northern counties on Saturday. The northwest wind along with the
resulting downslope flow should cause some clearing over our
southern counties.
High temperatures should favor the 50 to 55 degree range on
Saturday. Readings are not expected to get above the 40s in the
elevated terrain up north. These values are just about normal for
the 26th of November.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
On Saturday night and Sunday morning, northwest flow/CAA regime
will persist across the mid-Atlantic region as the area remains
positioned between high pressure centered over the TN Valley and
an ocean storm located several hundred miles off the NJ coast.
Sufficiently steep lapse rates and high EL heights in this
environment could support a snow streamer off Lake Erie to make it
as far downwind as the Pocono region. Subtle disturbances in the
mid levels digging toward the base of the longwave trough may
provide additional lift for a few snow showers in northern Carbon
and Monroe counties in northeastern PA. Snowfall accumulations
will be very light and limited to the higher-elevation ridges.
The ridge axis associated with broad high pressure progresses
eastward along the eastern seaboard later Sunday through Monday.
Dry weather, decreasing clouds, slightly below normal temperatures
and light winds can be expected.
The next storm system that could affect the area will organize on
the lee of the Rockies this weekend and then move into the
northern Great Plains early next week. While the low would still
be at a distant proximity from the Mid Atlantic, the attendant
warm front is forecast to lift northeastward through the forecast
area on Tuesday. The first round of precipitation with the warm
front looks to arrive late Monday night-Tuesday morning and taper
off Tuesday either late afternoon or evening.
Models continue to advertise a secondary wave of low pressure
organizing in the Gulf Coast states (near the southern tail of the
cold front) Tuesday night and then moving up the Appalachian
spine on Wednesday. Increasing synoptic lift and poleward
transport of Gulf of Mexico moisture linked to this secondary wave
could potentially enhance rainfall (in terms of coverage,
intensity and amounts) somewhere within the broader northeastern
quadrant of the CONUS. There are some solutions that bring several
inches of welcome rainfall to the CWA. A heavy rainfall outcome
for our area is no certainty 4-6 days out and will depend on the
track and strength of the cyclone, which the latest model guidance
differ on. Barring a major eastward shift in the low track, we
would be on the warm side of the system. Accordingly, rain should
be the only p-type with this event.
A cold front will eventually pass through the area sometime on
Thursday once the low tracks into the Northeast states. Breezy
westerly winds in wake of the departing low pressure system will
usher in cooler and drier air for the end of the work week.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Tonight...
For the terminals along the I-95 corridor and points southeast,
we expect MVFR ceilings to develop around midnight. The only
exception may be KILG, where we have inserted a TEMPO group that
flirts with MVFR. The MVFR ceilings will be associated with a
band of rain showers traversing the terminals. These showers will
gradually diminish around midnight, with VFR conditions expected
to return later tonight.
For ABE and RDG, ceilings are expected to maintain around 5k FT,
but fog is expected to lead to visibility restrictions. The TAFs
reflect MVFR conditions at both sites. Lower confidence at RDG
with a TEMPO group and higher confidence at ABE possibly closer
to IFR at times.
A light and variable wind into this evening is forecast to settle
into the northwest late tonight with speeds increasing to 4 to 8
knots.
Saturday...
MVFR in fog at ABE and RDG should improve to VFR by 14Z. For the
remainder of the TAF sites, VFR ceilings around 4.5k FT to 6k FT
are anticipated for Saturday.
A northwest wind is expected at speeds around 8 to 12 knots with
gusts of 15 to 20 knots.
OUTLOOK...
Saturday night through Monday...VFR. Breezy NW winds Saturday
evening and Sunday. Otherwise, light winds expected.
Monday night through Wednesday...Periods of rain could lead to sub-
VFR conditions. Rain looks to be the more widespread during the day
Tuesday and again on Wednesday.
&&
.MARINE...
Weak low pressure developing east of the NC/VA border tonight will
move out to sea and strengthen on Saturday.
Wind speeds and wave heights are forecast to remain below the Small
Craft Advisory criteria tonight and Saturday with one exception. As
the low strengthens, northwesterly wind gusts around 25 knots are
possible on Saturday on our ocean waters from around Atlantic City
southward. As a result, a Small Craft Advisory remains in effect
there beginning at 6:00 AM.
OUTLOOK...
Saturday night...SCA in effect for the coastal waters off S NJ and
DE. NW winds in these zones are forecast to be sustained around 20
kt with gust 25-30 kt while seas will be in the 3-5 ft range.
Sunday...The winds and seas will gradually subside. The SCA may
ultimately need to be extended into Sunday for a portion of our
southern coastal waters but confidence for a fourth period SCA is
low. Wind gusts to 25 kt will likely be more isolated.
Sunday night through Monday night...Winds and seas below SCA
criteria.
Tuesday through Wednesday...Wind speeds increase to 15-25 kt. Mixing
potential in S-SWly flow is becoming less optimal this time of year
for getting higher winds gusts over the marine. Therefore, we`ll
describe it as a marginal SCA setup, especially in the Delaware Bay
and nearshore waters.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 6 AM Saturday to 6 AM EST Sunday for
ANZ452>455.
&&
$$
Synopsis...Franck/Klein
Near Term...Franck/Iovino
Short Term...Iovino
Long Term...Klein
Aviation...Franck/Iovino/Klein
Marine...Franck/Iovino/Klein
Area Forecast Discussion
National Weather Service Raleigh NC
905 PM EST Fri Nov 25 2016
.SYNOPSIS...
A cold front will sweep through the area tonight. Cool high pressure
will build over the region through the weekend. This high will shift
to our east and off the coast on Monday, with warm air returning for
Tuesday and Wednesday.
&&
.NEAR TERM /Through Tonight/...
As of 905 PM FRIDAY...
According to the latest surface analysis, the cold front is situated
across the extreme NW corner of the forecast area, stretching from
just east of Lynchburg VA through the Triad and the southern
Foothills of NC, having moved little over the last several hours as
it waits for a mid level shortwave trough to its west (over ern
KY/TN/AL) to kick it eastward overnight. We`re already seeing a few
very light high-based showers over the NE Piedmont and the Coastal
Plain, where the strengthening forcing for ascent, including mid
level DPVA and upper divergence, will continue to act on a fairly
moist column (although not deeply so, mainly just below 700 mb) and
high surface dewpoints through the night. The HRRR has done a good
job the last several hours, and its depiction of rising coverage
(albeit still no better than scattered) east of Highway 1 overnight
is quite reasonable. QPF should be low, based on the fairly shallow
moisture and sub-50% coverage. Based on expected timing, shower
chances will be exiting the eastern CWA toward sunrise. Under mostly
cloudy skies, expect lows from around 40 NW to around 50-52 far SE,
where the front will be last to pass. -GIH
&&
.SHORT TERM /Saturday and Saturday Night/...
As of 227 PM FRIDAY...
Upper level trough axis will move through the area Saturday, as
surface high pressure builds in from the west. Drier air will bring
mostly sunny conditions to the entire area by the afternoon.
Northerly winds will usher in highs closer to normal, in the upper
50s to low 60s. Cooler lows in the lower 30s.
&&
.LONG TERM /Sunday through Thursday Night/...
As of 220 PM Friday...
Sunday-Monday: Seasonably cool and dry conditions will prevail at
the beginning of the long term period (Sunday) in association with
high pressure centered over the region. Similar (albeit slightly
warmer) conditions are expected on Monday as high pressure shifts
offshore and a light southerly return flow develops over the
Carolinas.
Monday Night-Thursday Night: Southerly return flow /warm advection/
will strengthen over the region Monday night into Tuesday and
persist through the day Wednesday as an expansive upper level trough
amplifies over the central US in response to a series of powerful
shortwaves expected to dig SE through the lower Midwest and
lift/eject NE across the Ohio Valley. An attendant cold front will
make little eastward progress /remain west of the Appalachians/
until mid-week. A potent shortwave expected to dig SE across TX
during the day Wed is progged to eject rapidly NE through the Deep
South into the southern Appalachians by Wed evening, accelerating
the cold front east of the mountains and into the Carolinas Wed
Night. The front is expected to progress offshore the Southeast
coast Thursday morning as the aforementioned shortwave lifts NE
offshore the Mid-Atlantic coast, rapidly deamplifying on the way.
Rich boundary layer moisture (characterized by sfc dewpoints in the
upper 50s to near 60F) will advect northward from the Gulf Stream
and eastern GOMEX into the Carolinas Mon Night/Tue as southerly
return flow strengthens in response to the amplifying upper level
trough west of the mountains, firmly establishing a warm sector over
the region by Tue afternoon. Strong S/SW return flow will allow the
warm sector to remain in place through the day Wed, until the cold
front progresses eastward through central NC Wed night or early Thu.
Expect mostly cloudy skies, episodic showers and above normal temps
(somewhat tempered by cloud cover/precip) throughout this period,
driven initially by warm advection and glancing DPVA (attendant
shortwave energy lifting NE across the TN/OH valley) Tue/Tue night,
followed by stronger DPVA and deep low-level convergence Wed
afternoon into Wed night as the cold front progresses eastward
through the Carolinas. In such a pattern, at this range it is
difficult to determine the precise timing of precip, precip amounts,
and whether or not deep convection will be possible. From a pattern
recognition standpoint, western portions of the state (including the
NW Piedmont) appear more likely to receive heavier precip and a
chance for thunderstorms. If guidance is correct in depicting rapid
deamplification of the shortwave lifting NE into the Mid-Atlantic,
precip amounts may be far lower in eastern portions of the state,
i.e. east of the Hwy 1 corridor. -Vincent
&&
.AVIATION /00Z Saturday through Wednesday/...
As of 625 PM Friday...
24 Hour TAF Period: Largely VFR conditions expected during the next
24 hours as a dry cold front moves through the area. The only
concern for sub VFR conditions would be with some IFR/MVFR ceilings
at KRWI with an outside shot of the same at KFAY. Otherwise winds
will shift from southwesterly to northwesterly beginning around 3z
in the Triad through about 6-7z at eastern TAF sites. Some gusts are
expected on Saturday afternoon, mainly between 15-20 kts. Gusts will
subside later in the day after sunset.
Long Term: Looking beyond the TAF period, the next chance for some
rain will be Tuesday and Wednesday as a cold front traverses the
area.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...30
LONG TERM...Vincent
AVIATION...Ellis
Area Forecast Discussion
National Weather Service Blacksburg VA
843 PM EST Fri Nov 25 2016
.SYNOPSIS...
Weak low pressure just south of the area will track east and
offshore overnight. High pressure enters from the northwest
Saturday and remains over the region into early next week. A
complex storm system works into the region Tuesday into Wednesday
bringing the potential for significant rainfall by midweek.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 820 PM EST Friday...
Area remains sandwiched this evening between weak low pressure
along the residual front to the south and the upstream surge of
colder air associated with the next shortwave trough. This influx
of cold advection just now entering the far western zones should
gradually slide south/east overnight as the main shortwave arrives
over the mountains early Saturday. Expect low clouds with this
colder air per latest IR pics to overspread much of the mountains
in the next few hours before seeing increasing northwest flow clip
off moisture to the lee of the Blue Ridge overnight. Latest HRRR
also continuing to develop a few showers out east with the wave to
the south but given ongoing dryness off evening soundings appears
overdone. Thus leaving out pops south and east for now. May also
see some upslope driven showers or flurries including spotty
drizzle/freezing drizzle northwest slopes late as well with the
low level moisture, so keeping in some low pops there. Otherwise
partly to mostly cloudy with clearing skies out east overnight as
drier air swings in later. Bumped up lows a little southeast of
the mountains overnight given lagging 850 mb cold advection until
late with increased mixing likely to also aid in keeping readings
in the 40s. Elsewhere expecting mostly 30s west with only the far
western tier likely going below freezing for the most part despite
cloud cover.
Previous discussion as of 305 pm EST Friday...
Weakening low over northern NC will track east off the VA/NC coast.
Effect on our area will be mostly cloudy skies, although enough lift
ahead of the low may be enough to produce showers around and east of
Danville and Yanceyville this evening. As we head west the flow will
pick up into the mountains nudging the moisture/cloud layer deeper.
That combined with a shortwave digging across the Central
Appalachians will result in isolated rain and snow showers, though
amounts will be limited or none at all.
Model guidance and wind fields suggest wind speeds behind the front
and eventually shortwave should be in the 8 to 15 mph range with
gusts of 20 to 30 mph mainly in the mountains and near the Blue
Ridge. Appears a few higher terrain locations could be gusting
toward 40 mph by dawn with 8h jet increasing to near 40 kts, but
mostly under 40 mph is expected.
Should be chilly tonight behind front as cold air advection takes
place especially in the mountains, as downsloping winds and cloud
cover keep the piedmont somewhat milder. Lows will range from the
lower to mid 30s west to upper 30s to lower 40s east.
Saturday will be cooler than normal in the mountains with clouds
hanging around through midday and finally clearing toward late
afternoon west of the Alleghanys. Sunshine will be out east of the
Blue Ridge most of the day. Winds will stay up enough mainly in the
morning. Highs ranging from the lower to mid 40s west, with some 30s
higher ridges, to lower to mid 50s across the foothills/piedmont.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM EST Friday...
A broad area of high pressure will be centered over the southern
Appalachains Saturday night. A nocturnal jet is expected to develop
over the Blue Ridge which will keep radiational cooling limited.
Overnight lows will fall to near normal levels with mid to upper 20s
across the mountains and lower 30s east of the Blue Ridge. The winds
from this nocturnal jet will not mix down to the lower elevations
until the inversion breaks Sunday morning, but then the jet weakens
through the day.
The center of high pressure will slowly move east-southeast Sunday.
As this ridge moves east, heights will build, ushering in warmer
weather. The mountains will benefit first seeing temperatures
rebound from the 40s Saturday to the lower 50s Sunday. The cool high
pressure will continue to influence temperatures east of the Blue
Ridge and will likely see similar temperatures Sunday as they did
Saturday (mid 50s).
Warm air will filter in aloft Sunday night with ridges possibly
being 10F warmer than the valleys. Temperatures will vary from the
mid 20s in mountain valleys to the mid 30s elsewhere.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM EST Friday...
Cool dry high pressure will move off the North Carolina coast
Monday. Both heights and southerly flow will increase, allowing
temperatures to warm 5F to 10F degrees above normal. An upper level
trough over the southern plains will push a trough of low pressure
across the Ohio and Tennessee Valleys Monday to the Appalachian
Mountains Tuesday morning. This trough will bring much needed rain
to the region. Rainfall amounts of a tenth to three tenth of an inch
(0.10 to 0.30) are possible with the higher amounts along the
eastern slopes of the Blue Ridge. This trough and rain should exit
to the south and east Tuesday evening and stall over North Carolina
Tuesday night.
A second stronger upper level trough will move out of the Rockies
Tuesday night. This trough will generate a series of low pressure
waves along the stall boundary, lifting it north and back over the
forecast area Wednesday. With the Gulf open and very good jet
dynamics crossing over the region, rainfall amounts of an inch or
more are likely. A cold front will push across the region by
Thursday afternoon with dry high pressure to follow and remain into
the weekend.
With a southerly flow and despite the rain showers Tuesday and
Wednesday, temperatures will be warmer than normal with highs in the
60s. Temperatures cool down back to normal for Thursday and Friday
following the frontal passage.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
As of 600 PM EST Friday...
Brief return to VFR across the region likely to be short lived as
upstream low clouds look to spill back into the western sections
this evening. This in advance of increasing cold advection
overnight along with passing shortwave energy that should allow
deeper northwest flow and subsequent upslope cloudiness later
tonight. However have slowed down arrival of any IFR cigs until
later this evening into the overnight hours at both KBLF/KLWB
given current trends, but still appears a MVFR canopy likely
during the early evening. This followed by a period of IFR/LIFR
at KBLF and MVFR/IFR at KLWB and perhaps MVFR at KBCB with mainly
VFR canopy at KROA after midnight.
As we head toward dawn Saturday skies clear out to the east of
the mountains enough for VFR, with sustained winds increasing to
8-15kts including gusts around 25kts, mainly from mid morning on
across the mountain locations. Will see cigs start to rise after
14z/9am at KBLF/KLWB with MVFR to VFR occurring through late in
the day. However degree of clearing remains uncertain at these
sites with potential for clouds to fill back in late in the day as
mixing/heating decreases.
Though some light precip may occur at KBLF and KLWB, coverage
looks way too spotty to include in the TAFs.
Should finally see skies clear Saturday night with VFR expected
across the region as high pressure slides in from the west.
Extended aviation discussion...
VFR expected Sunday through Monday. The next system arrives from
the southwest and will bring two periods of rainfall to the area
by Tuesday into Wednesday along with sub-VFR cigs and vsbys.
&&
.FIRE WEATHER...
As of 825 PM EST Friday...
Weak low to the south will move east overnight and give way to the
next surge of colder air that should push through the region
overnight. This will continue to bring low clouds and higher
humidity levels across the mountains overnight where some light
precip could occur along the northwest slopes by dawn. Expect
clouds to decrease east of the Blue Ridge later tonight although
humidity levels should remain on the moist side. Stronger upper
disturbance passes across by early Saturday should act to get the
winds back up to speeds of 10 to 20 mph, higher in the mountains.
By dawn Saturday will see gusts to 20 to 25 mph common mountains
and foothills and nearby valleys. Higher ridges above 3000 to 3500
ft could see gusts from the northwest as high as 35 to 40
mph...mainly in the predawn to midday time frame. Humidity will be
elevated thanks to the cooler temperatures and western cloud
cover.
High pressure enters overhead late Saturday night into Sunday which
will dry it out more, though winds will become light to calm.
Still looking promising for next weeks system with the front moving
in by Tuesday. Consensus is that 1-2 inches occurs in the Tue-Wed
time frame. This will help the wildfire situation considerably if
the pattern holds.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/WP
NEAR TERM...JH/WP
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...AMS/JH/WP
FIRE WEATHER...JH/WP
Area Forecast Discussion
National Weather Service Duluth MN
315 AM CST Sat Nov 26 2016
.SHORT TERM...(Today through Sunday)
Issued at 315 AM CST Sat Nov 26 2016
A strong inversion will lock the fairly widespread stratus deck
across the Northland through the rest of the weekend. Temperatures
will be on the mild side, though some minor adjustments have been
made to account for the more pessimistic cloud cover anticipated.
Warmer Sunday due to warm air advection ahead of the low pressure
system approaching from the southwest, with the warmer air moving
across the snow pack tonight likely leading to fog developing.
On the synoptic scale a mid-level ridge axis will move from west to
east across northwest Ontario with a weak warm front moving in from
the west over the upper Midwest. While some mid/high level clouds
will move across the region today associated with the warm front, a
strong low level inversion will trap the stratus deck prevalent
across northeast Minnesota and northwest Wisconsin this morning.
While surface heating may allow for some breaks in the stratus this
afternoon, any breaks in the clouds would likely be filled by
stratocu. Guidance has trended towards any breaks in the clouds
being fairly limited, though on fog channel satellite imagery and
surface obs this morning several pockets of clearing are noted, so
the guidance may be a bit too aggressive with the stratus deck.
Still, more clouds than sun today will lead to highs limited to the
mid 30s similar to Friday. Early RAP runs depict highs even cooler
in the low 30s where the stratus deck will likely stick and near 40
across inland NW Wisconsin where clearing is more likely, so some
adjustments may be necessary in a further update. Light south winds
through the day at around 5-10mph.
Tonight stratus will persist with fog likely across much of the
region due to warm southerly wind moving in across a decent
snowpack. NOHRSC analysis and co-op observations indicate a decent
4"+ snow pack across northeast Minnesota with some pockets of lesser
snow depths across parts of northwest Wisconsin such as the Hayward
lakes region. Still, with the southerly winds fog should be fairly
widespread. SREF and other short-term guidance is fairly aggressive
on coverage and intensity of fog, so felt confident introducing
areas/widespread fog wording in the forecast. Lows in the mid to
upper 20s.
Warmer Sunday with continued cloud cover. Southwest winds increasing
to 10 to 15 mph. Highs ranging from the mid 30s in northeast
Minnesota to low to mid 40s in northwest Wisconsin.
.LONG TERM...(Sunday night through Friday)
Issued at 315 AM CST Sat Nov 26 2016
The main story for the long-term looks to be a broad mid-level
shortwave trough that develops out of the Four Corners region that
is progged to translate to the northeast across NE and SD. A strong
165+ kt 250 mb jet streak develops in association with this
shortwave, which places the Upper Midwest in the left exit region of
the jet, in an area of enhanced divergence aloft. An upper-level cut-
off low develops, which results in a nearly stationary sfc low
pressure across the region, sticking around from Monday through the
day Thursday. Southerly flow and warm air advection in the low
levels look to increase during the day Monday, with GFS 925 mb
temperatures warming into the 5-10 degree C range. These values look
to be a bit too warm as the NAM/ECMWF models are going with values
more between 0-5 degrees C. Still, the thermal profiles suggest
precipitation on Monday to start as rain. The models are hinting at
some elevated instability Monday afternoon as well, with values of
elevated convective available potential energy between 50-100 J/kg
in the NAM and GFS model soundings. So, I kept a slight chance of
thunderstorms Monday afternoon. Then, the general thermal profile
cools, which suggests a transition to a wintry mix Monday evening
into Tuesday morning. Chances of precipitation look to continue
through Friday as the low pressure system very slowly moves to the
east during this time period. Expect skies to be mostly cloudy
otherwise. High temperatures look to stay above normal Monday
through Wednesday before temps drop to more normal levels Thursday
as cold air advection behind the low pressure system moves in. Highs
Monday through Wednesday look to be in the mid to upper 40s Monday
into the mid to upper 30s Tuesday and Wednesday. Winds look to also
intensify due to a tightening sfc pressure gradient associated with
this sfc low on Monday as southeast gusts between 20-25 kts are
expected.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1118 PM CST Fri Nov 25 2016
IFR and LIFR ceilings and fog will prevail through day break. The
arrival of dry air will gradually erode the low clouds Saturday.
However, confident is not high all locations will clear out and
expect the low clouds and fog to quickly redevelop Saturday
evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 35 28 38 36 / 0 0 10 80
INL 35 27 36 33 / 0 0 0 70
BRD 37 27 38 37 / 0 0 10 80
HYR 38 29 42 38 / 0 0 0 80
ASX 39 30 42 38 / 0 0 0 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...JJM
LONG TERM...JTS
AVIATION...Graning
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
352 AM CST Sat Nov 26 2016
.SHORT TERM.../Today through Tonight/
Issued at 351 AM CST Sat Nov 26 2016
A pleasant Saturday is shaping up for the state of Iowa with
southwesterly return flow and strong H850 WAA helping to push
temperatures into the upper 40s north to the upper 50s south. Made
minimal changes to the going max temp forecast given the possibility
of increasing cirrus cloud cover and the going forecast already on
the upper end of the guidance envelope. Increased sky cover over the
northern 2/3rds of the CWA for today and into this evening given the
influx of cirrus cresting the H500 ridge over the western High
Plains on IR imagery. NAM/RAP/GFS vertical RH cross-sections all
hold the cirrus into the early afternoon hours, though there are
some timing differences in the clearing of the clouds with the RAP
in particular holding the clouds well after sunset in the NE.
Tonight will be quiet weather-wise with increasing high clouds
streaming in from the SW towards sunrise ahead of our Sunday rain
event.
.LONG TERM.../Sunday through Friday/
Issued at 351 AM CST Sat Nov 26 2016
Vigorous short wave energy will cross over the Rockies early
Sunday with strong lee side cyclogenesis occurring from eastern
Colorado and into Nebraska. The deepening sfc low will lead to
strong moisture advection streaming north from the Gulf of Mexico
and into Iowa. Profiles will start the day quite dry but will
saturate quickly. As profiles saturate the mid level lapse rates
will steepen and weak MUCAPEs will develop. Thus expect elevated
thunderstorms to develop during the day. Showers and a few
thunderstorms may linger into early Sunday evening then subsidence
in the wake of the passing PV anomaly will arrive along with a
return of drier mid level air. The near surface moisture will
remain along with some turbulence and vertical ascent and this may
result in drizzle development.
The upper level energy will evolve into a deepening upper low
pressure that will slow and linger over the Dakotas on Monday then
move slowly east into Minnesota on Tuesday before eventually
reaching the mid Great Lakes on Thursday. How long clouds linger
on Monday is the main challenge for the temperature forecast. If
the clouds scatter, mixing will push high temperatures back into
the mid to upper 50s for central and southern Iowa. The primary
push of cold advection arrives late Monday afternoon and into the
overnight then 850 mb temperatures will continue to cool as the
upper low progresses east. The 850 mb temperatures will be near
-8C by Thursday. Mixing during this time will keep highs in the
30s to 40s with overnight lows generally in the 20s. Light rain or
snow will be possible over northern Iowa Tuesday into Wednesday
with little to no accumulations expected. The remainder of the
extended forecast will be mainly dry.
&&
.AVIATION.../For the 06Z TAFS through 06Z Saturday night/
Issued at 1146 PM CST Fri Nov 25 2016
Patchy fog has developed across about the eastern half of Iowa
this evening as expected, but coverage is very low. A few
stations just east of OTM and just northwest of MCW have gone down
to M1/4SM for a bit, but so far fog has avoided the terminals. The
surface ridge axis has been very slowly creeping northeast and
should continue to do so, which would gradually advect the patches
of fog out of our area and away from the terminals later tonight.
Have included 3SM BR tempo groups at MCW/ALO/OTM for the next two
or three hours, but there is a possibility that visibility could
briefly drop much lower than that. From mid-morning Saturday
through the remainder of the TAF period VFR conditions are
expected with nearly clear skies.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Skow
LONG TERM...Donavon
AVIATION...Lee
Area Forecast Discussion
National Weather Service Sioux Falls SD
310 AM CST Sat Nov 26 2016
.SHORT TERM...(Today and Tonight)
Issued at 310 AM CST Sat Nov 26 2016
500 mb ridge is moving east across the north central CONUS. Moisture
streaming in out ahead of a large short wave just west of the CA
coast, is resulting in cirrus covering much of the CWA this morning.
Another quiet weather day as height rises ahead of the
aforementioned low over the Pacific ocean will bring mild high temps
in the mid 40`s to mid 50`s. Filtered sun is expected today as
model time/height sections show a persistent layer of moisture from
300-500 mb, which will result in cirrus most of the day.
.LONG TERM...(Sunday through Friday)
Issued at 310 AM CST Sat Nov 26 2016
A strong upper low approaching from the southwest will bring
rain into the area Sunday afternoon, with rain chances increasing
steadily from the southwest starting just before noon. With the
system being stronger than on previous model runs, instability
sufficient for thunderstorms aloft is indicated to spread quickly
over most of the area during the peak Sunday afternoon and evening.
The NAM and GFS both show sufficient MUCAPE up to 500 j/kg. The
strength of the surface system, which will bring strong
southeasterly winds to northwest Iowa Sunday evening, would suggest
enough low level shear for severe storms. However, it can be seen on
BUFKIT model soundings that the lower levels will be too cool for
surface based convection, so will not mention severe storms, as per
the SPC day 2 outlook for this area. The strong Sunday evening winds
should be below wind advisory criteria.
High temperatures Sunday should be in the mid 40s to lower 50s.
With the best and deepest moisture shown staying south of the area,
rainfall amounts through Sunday night are expected to generally be
below a half inch. Thunderstorms could produce locally higher
amounts.
Cooling aloft could bring some snow mixing with rain in southeast
South Dakota late Sunday night and Monday. During this time,
precipitation over the area will become light and coverage will
decrease as the low, both at the surface and aloft, moves northeast
into North Dakota and northern Minnesota. The slow nature of the
cooling should keep any snow accumulations to less than one inch.
All models keep the low generally stationary over North Dakota and
northern Minnesota Monday night through Wednesday. This is close to
the earlier EC solution, that model being the only one showing this
scenario the previous two nights. Moisture flowing around the low
will result in areas of light precipitation during this time, mostly
north of Interstate 90. Continued slow cooling will tend to change
mixed rain and snow to mostly light snow, with some diurnal
variation in precipitation type due to the lower levels warming and
cooling a bit. The weak nature of the lift, and weak thermal
contrast will keep amounts light, with snow accumulations, if any,
an inch or less. As the low begins to move east by Thursday, some
light snow could linger that day in part of southwest Minnesota. Dry
weather should prevail over all of the area Friday.
High temperatures will be mostly in the 40s Monday, mid 30s to lower
40s Tuesday, and mostly in the lower to middle 30s the rest of the
week. These late week temperatures will be fairly close to normal
for the start of December.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1047 PM CST Fri Nov 25 2016
Main aviation concern will be the potential for patchy fog to
develop late tonight. The NMM and to a lesser extent, the HRRR
indicate that patchy fog will be possible mainly along and east of
the James River, as winds become light overnight. However, with
a greater amount of cirrus blanketing the entire forecast area,
have decided to continue leaving out mention of any fog from the
TAFs.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...Sally
LONG TERM...
AVIATION...
Area Forecast Discussion
National Weather Service Lincoln IL
332 AM CST Sat Nov 26 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 332 AM CST Sat Nov 26 2016
Low clouds have been slow to move out of central and southeast
Illinois, with low level moisture trapped beneath a strong
subsidence inversion. However, satellite loops suggest the back edge
of the clouds is continuing to make steady progress east over the
last several hours (although slower than any model solution). With
this in mind, have largely used satellite extrapolation to time
clearing today, which should have low cloud deck entirely east of
the area by early afternoon.
Otherwise, neutral upper-level flow and surface high pressure will
keep quiet weather conditions across the region through the period.
Temperatures will trend milder, climbing a little above normal
today, as low-level flow turns more southerly and increases on the
back side of the surface ridging.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 332 AM CST Sat Nov 26 2016
Upper level ridge over the MS river valley at sunrise Sunday, will
shift east over IL by 18Z/noon on Sunday and into the Ohio river
valley by 6 pm Sunday. Meanwhile surface high pressure ridge over
the Southeast States will drift toward the Carolina coast by sunset
Sunday. Expect clouds to increase from the west during the day
Sunday with a 20-30% chance of showers late Sunday afternoon west of
Peoria and Springfield as next storm system approaching the Prairie
State. Highs of 50-55F on Sunday as southerly winds pick up to
breezier levels by Sunday afternoon. The mildest readings near 55F
will be from Jacksonville sw and from Lawrenceville south.
A vigorous upper level troff off the West Coast will develop a
strong cutoff low over the eastern Dakotas by 12Z/Mon while surface
low pressure over eastern CO at sunrise Sunday ejects northeast to
near the eastern SD/ND border by 12Z/Mon. A widespread band of rain
showers will spread east across IL during Sunday evening, reaching
the Wabash river valley early overnight Sunday night. Rain showers
become less numerous Monday morning especially nw half of CWA, then
will see another increase in showers and isolated thunderstorms
during Monday afternoon and Monday evening, before diminishing
quickly from the west overnight Monday night. Rainfall amounts to
average around 1 inch with 1.25 inches in southeast IL. Rather
strong southerly winds on Monday into Monday evening helping pump in
deeper gulf moisture into IL. SPC day3 outlook has general risk of
thunderstorms across IL Mon afternoon/evening while marginal risk of
severe storms is sw of IL over southern MO into AR and slight risk
of severe storms over Louisiana and east Texas where better
instability will be. Lows Sunday night of 40-45F, Highs Monday in
the low to mid 50s, Lows Monday night in the low to mid 40s (mildest
readings in eastern IL).
Skies to become partly to mostly sunny by midday Tue as low pressure
moves into northeast MN. Fairly mild highs on Tue ranging from lower
50s nw of IL river to 55-60F over southeast IL. An upper level trof
then deepens into the Great Lakes and IL by Wed/Thu cooling temps
closer to normal and to bring more low cloud cover especially
northern CWA from I-74 north. 00Z models have trended further
southeast with qpf for Wed afternoon/evening and now our CWA appears
to stay dry with most of the qpf southeast of the Ohio river. Dry
weather with seasonable temps expected late next week with
precipitation chances confined to the Great Lakes region.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1146 PM CST Fri Nov 25 2016
Main issue remains with the progression of the clearing of MVFR
clouds. Satellite images show the back edge of the clouds
marching east, already reaching to a line from PIA to SPI at
0530z/1130pm. There has been some minor slowing of the steady
progression in the last hour, with slight back-building of clouds
at times. Forecast soundings from HRRR and RAP are catching up to
the speed of the clearing, and show all TAF sites becoming VFR
before sunrise, with CMI the last at 11z. Therefore, have
advanced the clearing of clouds from west to east during the
first 6 hours of this TAF period.
Light fog will be likely in the wake of the clearing, with PIA
having the best chances at IFR vis in fog. The HRRR and RAP keep
fog at 6sm or better at all TAF sites, while the NAMNest and GFS20
showing fog west of I-57. Fog was only added to PIA for now, but
could be needed for the I-55 terminals of BMI and SPI.
Winds will remain westerly at 4-7kt the rest of tonight, then
become southwest after sunrise. Southwest wind speeds are
projected to increase to 10-14kt Saturday afternoon in response to
an intensifying warm advection flow aloft. Winds will diminish to
7-9kt Saturday evening as they shift to the south.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Bak
LONG TERM...07
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Miami FL
429 AM EST Sat Nov 26 2016
.DISCUSSION...
A few brief showers have pushed westward across the
east coast metro region this morning from the Atlantic waters.
Otherwise, the radar was been relatively quiet. Last nights 00Z MFL
sounding showed a moderately moist layer from the surface up to
around 850 mb, with dry air aloft. Through early this morning, as
the boundary layer remains decoupled and temperatures drop,
patchy fog may develop across the interior. A weak cold front
will push southward down the north/central portion of Florida
during the afternoon. Ahead of this feature, a minor rise in
moisture and instability will lead to a slight chance of showers
over the Atlantic waters and immediate east coast region. Not
expecting much accumulation out of these showers, as the latest
HRRR and WRF model runs depict only spotty activity. On Sunday,
as the front advects south of the region, winds will shift to a
more northeast direction. Dry weather will generally prevail
through mid week, behind the frontal passage, as a ridge of high
pressure draws near. This ridge will allow for the flow to become
east/southeast and breezy at times with a tightening pressure
gradient, along with increasing low- level moisture.
The front passage will also act to lower temperatures across the
region. Maximum temperatures Sunday and Monday are only forecast
to top out in the upper 70s along the immediate east coast to
around 80 degrees elsewhere. Pressure increases aloft on Tuesday
and Wednesday should allow for temperatures to rise to the low 80s
along the east coast metro and up to the mid 80s inland. By
Thursday, temperatures may peak from 85 to around 87 degrees over
western sections of the interior. These values are over 5 degrees
warmer than normal for this time of year.
By late Thursday, the 00Z GFS progs another weak front to press
southward across the region. This feature should once again produce
enough lift and instability to generate a few showers over south
Florida, before exiting the area on Friday.
&&
.MARINE...
The flow will shift to a northerly direction today at generally
around 10 knots as a weak frontal boundary crosses the region. The
flow will increase and become east/southeasterly early next week
as high pressure reestablishes itself to the north of the region.
Scattered showers are possible today into Sunday associated with
the passing frontal boundary. Drier weather will return behind the
frontal passage early next week. Seas will be 4 feet or less
through early Sunday, increasing to 5-7 feet over the Gulf Stream
late Sunday into early Monday.
&&
.AVIATION...
Light wind tonight will continue until after sunrise, as high
pressure to the east weakens ahead of an approaching cold front.
The front will be weak, and South Florida looks to be just on the
tail edge of the front by Sunday morning. This will keep most of
the shower activity offshore tomorrow. For today, some brief,
isolated showers will be possible, with VFR conditions forecast
through the TAF period. In the interior, there is a chance of some
fog formation, mainly in the western lake region.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 82 65 78 70 / 20 30 20 10
Fort Lauderdale 82 68 79 70 / 20 30 20 10
Miami 83 66 80 69 / 20 30 20 10
Naples 81 62 80 63 / 10 10 0 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
DISCUSSION...27/JT
MARINE...27/JT
AVIATION...13
Area Forecast Discussion
National Weather Service Morristown TN
321 AM EST Sat Nov 26 2016
.SHORT TERM (Today and Tonight)...
Water vapor imagery indicates shortwave aloft with axis extending
southward across East Tennessee will shift east of the area by
this afternoon. Meanwhile, surface high centered over southern
Illinois this morning will move east becoming centered over SW
Virginia by Sunday morning.
Behind the upper trough axis, low cloud deck is descending into the
area this morning. Guidance suggests that this cloud deck will
clear from south to north through the day today. The timing of this
clearing is important as daytime highs are likely to be inhibited
in those areas remaining cloudy during the afternoon. HRRR and
RUC13 indicate that the southern third of the area will see clear
skies by this afternoon, however, northern third will likely
remain in clouds for the better part of the day limiting daytime
highs to the middle and upper 40s while those areas in the southern
third are expected to reach into the middle 50s.
With good afternoon mixing, expect gusty N to NE winds of 10-15 mph
over the southern third of the area. Fortunately, a very shallow
layer of moisture near the surface should help to keep relative
humidities at or above 40% and help to slightly reduce the fire
weather threat while in this gusty wind regime today. Winds will
decrease area wide after sunset as the low-level decouples and the
surface high sits across the area.
With all of the area finally clearing out by tonight...we will have
a cold night with lows below freezing across the entire area...and
about 5-7 degrees below seasonal climatology.
.LONG TERM (Sunday through Friday)...
The main theme is that the Gulf of Mexico moisture finally opens
up and is pulled northward into the Tennessee Valley and southern
Appalachians by mid-week next week.
For Sunday...ridging both surface and aloft will remain in control
producing dry and unseasonably mild conditions.
For the first half of next week...a deep long-wave upper trough
over the Rockies/western high Plains will move slowly east. A
series of jets exiting the trough into the Plains...northeast into
the Ohio Valley/Great Lakes will induce strong pressure falls over
the mid- section of the nation. This will finally pull Gulf
moisture northward into the region.
The series of upper jets will strengthen the fronto-genetic forcing
along boundaries moving into the area for Monday night/Tuesday
morning...and then again Tuesday night through Thursday morning. A
shield of rain showers can be expected along each fronto-genetic
boundary producing much needed rainfall across the area. Rainfall
totals through the period of 1 1/2 inches northeast Tennessee Valley
to 3 inches south.
Instability will be enough to warrant isolated thunder for Tuesday
night. Besides the rain...the pressure falls will produce a strong
850mb jet with southerly winds of 60-70kts possible. The strong
winds will likely produce very windy conditions (possibly high wind
warning criteria) for the far eastern Tennessee Mountains and
adjacent foothills. A mountain wave event is possible.
Drier weather returns for Thursday and Friday as surface ridging
builds into the region.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 56 31 62 42 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 50 27 60 37 / 0 0 0 0
Oak Ridge, TN 53 28 59 37 / 0 0 0 0
Tri Cities Airport, TN 47 26 58 28 / 0 0 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
EJH/DH
Area Forecast Discussion
National Weather Service Portland Oregon
921 PM PST Fri Nov 25 2016
.SYNOPSIS...The wet slow moving front of the past 24-48 hours has
weakened and moved east of the forecast area with decreasing rain. A
new low was developing off the coast with a redeveloped frontal
boundary off the coast. This low will move north into western
Washington late tonight and Saturday morning, pushing the offshore
front onshore for another bout of decent rains and some coastal
winds. This front will move east of the forecast area Saturday night,
but not before dropping snow levels to near or below pass elevations
again with some snow accumulations at the passes Saturday night.
Another colder system is forecast to drop in from the northwest late
Sunday and especially Sunday night for another bout of rain with
possibly heavy snow in the Cascades Sunday night. Precipitation will
taper off by Tuesday for a well deserved break in the weather before
the next system arrives Wednesday.
&&
.SHORT TERM...Tonight through Monday...Rain has decreased across most
of southwest Washington and northwest Oregon this evening as the
front that brought heavy rain to the area on Thanksgiving finally
weakened and the upper forcing moved east. Rivers were receding,
though a couple were receding very slowly. The South Yamhill River at
McMinnville continues to rise but based on evening rainfall should
begin receding in the next couple of hours.
However, another low was developing off the coast this evening and is
forecast to move inland into western Washington late tonight and
Saturday morning. Some gusty winds are expected along the coast as
the low moves inland to our north, but at this point probably staying
below high wind criteria. This low will also push the associated
frontal band that is off the coast onshore mainly along the coast
later tonight and then through the inland areas during the day
Saturday. The front will move east of the Cascades Saturday night.
This front will bring a good dose of rain to the forecast area
Saturday and Saturday evening, but not nearly as heavy as on
Thanksgiving. Snow levels, which rose well above the passes this
afternoon, will drop back to near the Cascade pass elevations late
Saturday and below the passes Saturday night. Amounts could reach the
3 to 6 inch range. Showers will continue over the area into Sunday in
northwest onshore flow.
Another colder system is forecast to drop in from the northwest late
Sunday and especially Sunday night with another good dose of valley
rain and mountain snow. Snow levels will be below the Cascade passes
with this system. Amounts look higher Sunday night than those
expected Saturday night, with 6 inches and possibly higher a good bet
in many areas of the Cascades. There is some pressure gradient with
this system as well, so there should be some breezes in much of the
forecast area as well. Showers in northwest low level onshore flow
will continue on Monday with snow in the Cascades.
The big takeaway is be ready for snow in the Cascade passes beginning
Saturday night and continuing into early next week. Tolleson
.LONG TERM...No Changes. Previous discussion follows...
(Monday night through Friday)...Models remain in pretty good
agreement overall through the end of the week, with mainly minor
timing issues. Mon night and Tue a ridge moving across will bring an
end to the showers associated with the departing trough. Another
fairly strong shortwave and cold front arrives from the west Tue
night bringing another round of rain. With origins in the north
Pacific, snow levels will again drop down to pass levels or a little
lower. Showers follow late Tue night and slowly decrease Wed night
and Thu as ridging builds in from the west. After a brief break under
the ridge Thu night, another chance for rain moves in from the nw Fri
as the tail end of a warm front approaches off the Pacific.
&&
.AVIATION...Main warm frontal rains have stayed offshore, however,
there were just enough breaks in the clouds to allow KHIO and KLSE
temperatures to fall near the dew points and bring IFR vsbys with
LIFR cigs at ksle. other areas remain VFR at this time under Cigs
6000+ feet. Will not likely see improvement at KHIO or KSLE until
13-15z tomorrow morning when southerly winds increase and will mix
out the low level moisture. KEUG may be the next location to
bottom out after a couple hours more of cooling. Otherwise, the
remaining terminals appear to remain VFR until rain intensifies
again under lowering Cigs from a passing warm front and associated
compact upper trough. This should happen around 13z for KAST and
closer to 18z for KEUG. Looks like Cigs will generally remain
015-025 through 27/06z.
KPDX AND APPROACHES...Cigs should remain around 5000-7000 ft
overnight until heavier rain moves in Saturday morning around
16-18Z. Conditions will lower to MVFR (015-025 Cigs and maybe 5SM
Vsby) and remain predominantly so through Saturday evening. /JBonk
&&
.MARINE...Confidence extremely low regarding the next 12-18 hours
but have seen enough signs in surface winds and satellite imagery
to believe a complex surface low will deepen near the southern
oregon coast then stretch northward over the waters tonight. Most
notably the last few hours of the HRRR remain rather aggressive in
bringing moderate to high end gale gusts across the entire waters
at some point tonight and early saturday daylight hours. The GFS
and NAM continue to support sending the majority of the splitting
energy north while the ECMWF continues to send the bulk of energy
south. Have decided to issue a gale warning for all of the waters
despite having far lower confidence than typically required given
the shear potential for gusts 45-50 kt under a worst case
scenario.
Winds will turn northwesterly behind the low pressure center as it
moves toward shore overnight tonight through early tomorrow and
likely maintain SCA wind gust strength. A weaker front moves
across the waters from the NW on Saturday evening, but winds
likely will mostly remain below 20 kt, with gusts to 25 kt only
possible in PZZ275. We see another front move through Sunday
night, with the potential to bring low- end gales to our waters.
Winds look to stay up above 20 kt through at least midweek under
northwesterly winds.
Seas currently around 13 to 15 ft will hold through this evening in
the waters off of Oregon`s Central Coast. Farther north will see
seas hold around 12 to 13 ft until this front passes through.
Behind the front...expect seas to fall to around 9 to 12 ft by
Saturday night, with highest seas south. Seas hover around 10 ft
through the day on Sunday, until we start to see large swell build
seas into the middle-to-upper teens late Sunday night into Monday.
This larger swell train stems from a decaying low originating near
the Aleutian Islands. Seas stay up in the middle-to-upper teens
through early next week. JBonk/McCoy
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Flood Watch until 10 PM PST this evening for Central Willamette
Valley-Greater Portland Metro Area-South Willamette Valley.
WA...None.
PZ...Gale Warning until 10 AM PST Saturday for Waters from Cape
Shoalwater WA to Florence OR from 10 to 60 nm.
Gale Warning from midnight tonight to 10 AM PST Saturday for
Coastal Waters from Cape Shoalwater WA to Florence OR out
10 nm.
Small Craft Advisory for Rough Columbia River Bar until 4 AM
PST Saturday.
Small Craft Advisory for Rough Columbia River Bar from 1 PM to
5 PM PST Saturday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.
Area Forecast Discussion
National Weather Service Cleveland OH
923 AM EST Sat Nov 26 2016
.SYNOPSIS...
One final trough will cross northeast OH/northwest PA early this
morning. High pressure will then build over the region from the
southwest remainder of the weekend. Low pressure will move from
the central Plains to the upper Midwest early next week...bringing
an occluding front across the local area on Monday. The low will
move across the Great Lakes through Friday with periods of
unsettled weather.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Temperatures have inched their way into the upper 30s this morning
and all the obs are showing rain. There is likely still some
mixed precip or even light snow occurring at higher elevations.
Given the radar and latest HRRR have stretched the precip mention
back west through the MFD area. Not expecting much if any snow
accumulation today. No changes to temperatures.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
It will take through a good portion of the night to get the
surface ridging/H8 warming eastward enough to put an end to the
snow shower chances across the far east snowbelt. We may get an
inch inland NW PA overnight. Dry elsewhere. Temperatures tonight
below freezing away from the lake will be reasonable.
Skies will become partly cloudy on Sunday/Sunday evening from
west to east. A warming trend will take place from Sunday through
Tuesday as the high shift east and strong low level jet pulls
warmth and moisture northward from the Gulf. Deep trough across
the Rockies early next week will eject one significant shortwave
to the upper Midwest with surface cyclone development. This will
support an expansion of showers into the area beginning Monday
and continuing through Monday night...before exiting Tuesday with
an occluded frontal passage. There is decent timing agreement and
have continued the to categorical precipitation chances centered
on Monday night. Raised temperatures across the central and east
Monday...counting on the rain holding off long enough and leaning
toward the ECMWF and NAM. Tuesday...if all goes as planned...a
significant dry slot and southwest flow follows the exiting
showers and will continue with the mild temperatures near 60/lower
60s.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
The long term begins on Wednesday with models in general agreement
showing low pressure in NERN MN. Over the next 24 hours the upper
system remains fairly stationary while the surface system elongates
and shifts out over the central Great Lakes. By Friday the surface
system will be off the coast of Maine while the upper system lags
over the lakes. The area will be in gradual cold advection behind a
weak cold front which passed on Tuesday. Still, flow will be from
the southwest and daytime highs should remain mild in the 50s.
Models have the best moisture east of the area but still with flow
out of the gulf will retain chance pops west and central and likely
pops far east. Thursday 850mb temps drop to -4 to -6c by late
afternoon as moisture from the upper system begins to drop into the
area from the northwest. For now will confine precip to the north
central and northeast counties downwind of the lake. Friday much the
same. Flow will veer a bit northwest and with similar 850mb temps
will continue precip from mainly lake effect. Given trajectory of
the moisture may have to add chance pops to the remainder of the
area if later runs continue to support rh across the area. High
temps mainly in the 40s Thursday and Friday.
&&
.AVIATION /12Z Saturday THROUGH Wednesday/...
High pressure will build toward the area today however plenty of
low level moisture is trapped across the area. Conditions have
been improving in the west with KTOL and KFDY VFR. More MVFR CIGS
to our west however and concerned that CIGS drop back to MVFR
during the morning hours. Conditions elsewhere MVFR with IFR CIGS
at KYNG. Also lake effect showers in vicinity of KERI will bring
conditions to IFR at times today. Expecting restrictions to
persist with a few hours of mid day VFR possible...mainly KMFD and
KCLE. Tonight guidance diverges and have chosen to continue with
MVFR CIGS dropping in places to IFR with a low level morning
inversion.
OUTLOOK...Non-VFR likely through Tuesday.
&&
.MARINE...
Will continue small craft headline as is through 10am. Winds remain
from the WSW at 15 to 20 knots or so and should continue at around
15 knots through much of the day and into tonight before dropping
back to around 10 knots as a ridge extends across the lake from the
south. Expect waves will be dropping slowly through the period.
Sunday the ridge will drift east and deep low pressure will move out
of the Rockies to Nebraska. Winds should begin to back to the
southwest and eventually south-southeast as this system moves
further out into the northern plains. Speeds will remain in the 10
to 15 knot range Sunday into Monday before increasing to 10 to 20
knots late. The low will reach MN and Lake Superior by Monday and
should move little through Tuesday and even into Wednesday. Winds
Tuesday will continue from the southeast early reaching speeds in
the 20 to 25 knot range before turning southwest and decreasing to
10 to 15 knots behind a weak cold front. Wednesday expect winds from
the southwest ahead of another approaching cold front/surface
trough.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Oudeman
NEAR TERM...Kubina
SHORT TERM...Oudeman
LONG TERM...TK
AVIATION...TK
MARINE...TK
Area Forecast Discussion
National Weather Service Duluth MN
612 AM CST Sat Nov 26 2016
.SHORT TERM...(Today through Sunday)
Issued at 315 AM CST Sat Nov 26 2016
A strong inversion will lock the fairly widespread stratus deck
across the Northland through the rest of the weekend. Temperatures
will be on the mild side, though some minor adjustments have been
made to account for the more pessimistic cloud cover anticipated.
Warmer Sunday due to warm air advection ahead of the low pressure
system approaching from the southwest, with the warmer air moving
across the snow pack tonight likely leading to fog developing.
On the synoptic scale a mid-level ridge axis will move from west to
east across northwest Ontario with a weak warm front moving in from
the west over the upper Midwest. While some mid/high level clouds
will move across the region today associated with the warm front, a
strong low level inversion will trap the stratus deck prevalent
across northeast Minnesota and northwest Wisconsin this morning.
While surface heating may allow for some breaks in the stratus this
afternoon, any breaks in the clouds would likely be filled by
stratocu. Guidance has trended towards any breaks in the clouds
being fairly limited, though on fog channel satellite imagery and
surface obs this morning several pockets of clearing are noted, so
the guidance may be a bit too aggressive with the stratus deck.
Still, more clouds than sun today will lead to highs limited to the
mid 30s similar to Friday. Early RAP runs depict highs even cooler
in the low 30s where the stratus deck will likely stick and near 40
across inland NW Wisconsin where clearing is more likely, so some
adjustments may be necessary in a further update. Light south winds
through the day at around 5-10mph.
Tonight stratus will persist with fog likely across much of the
region due to warm southerly wind moving in across a decent
snowpack. NOHRSC analysis and co-op observations indicate a decent
4"+ snow pack across northeast Minnesota with some pockets of lesser
snow depths across parts of northwest Wisconsin such as the Hayward
lakes region. Still, with the southerly winds fog should be fairly
widespread. SREF and other short-term guidance is fairly aggressive
on coverage and intensity of fog, so felt confident introducing
areas/widespread fog wording in the forecast. Lows in the mid to
upper 20s.
Warmer Sunday with continued cloud cover. Southwest winds increasing
to 10 to 15 mph. Highs ranging from the mid 30s in northeast
Minnesota to low to mid 40s in northwest Wisconsin.
.LONG TERM...(Sunday night through Friday)
Issued at 315 AM CST Sat Nov 26 2016
The main story for the long-term looks to be a broad mid-level
shortwave trough that develops out of the Four Corners region that
is progged to translate to the northeast across NE and SD. A strong
165+ kt 250 mb jet streak develops in association with this
shortwave, which places the Upper Midwest in the left exit region of
the jet, in an area of enhanced divergence aloft. An upper-level cut-
off low develops, which results in a nearly stationary sfc low
pressure across the region, sticking around from Monday through the
day Thursday. Southerly flow and warm air advection in the low
levels look to increase during the day Monday, with GFS 925 mb
temperatures warming into the 5-10 degree C range. These values look
to be a bit too warm as the NAM/ECMWF models are going with values
more between 0-5 degrees C. Still, the thermal profiles suggest
precipitation on Monday to start as rain. The models are hinting at
some elevated instability Monday afternoon as well, with values of
elevated convective available potential energy between 50-100 J/kg
in the NAM and GFS model soundings. So, I kept a slight chance of
thunderstorms Monday afternoon. Then, the general thermal profile
cools, which suggests a transition to a wintry mix Monday evening
into Tuesday morning. Chances of precipitation look to continue
through Friday as the low pressure system very slowly moves to the
east during this time period. Expect skies to be mostly cloudy
otherwise. High temperatures look to stay above normal Monday
through Wednesday before temps drop to more normal levels Thursday
as cold air advection behind the low pressure system moves in. Highs
Monday through Wednesday look to be in the mid to upper 40s Monday
into the mid to upper 30s Tuesday and Wednesday. Winds look to also
intensify due to a tightening sfc pressure gradient associated with
this sfc low on Monday as southeast gusts between 20-25 kts are
expected.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 610 AM CST Sat Nov 26 2016
IFR and LIFR ceilings and vsbys will persist through the day
today due to trapped moisture under a strong inversion. Confidence
is low regarding vsby reductions this afternoon as some model
guidance is very bullish on how low the reductions get to. Some
guidance indicated LIFR vsbys, but not expecting to go quite that
low this afternoon, at least not until later in the evening when
dew point depressions reduce. Most places may see 1/2SM for vsbys,
and cigs down as low as 200-300 ft.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 35 28 38 36 / 0 0 10 80
INL 35 27 36 33 / 0 0 0 70
BRD 37 27 38 37 / 0 0 10 80
HYR 38 29 42 38 / 0 0 0 80
ASX 39 30 42 38 / 0 0 0 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...JJM
LONG TERM...JTS
AVIATION...JTS
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
538 AM CST Sat Nov 26 2016
.SHORT TERM.../Today through Tonight/
Issued at 351 AM CST Sat Nov 26 2016
A pleasant Saturday is shaping up for the state of Iowa with
southwesterly return flow and strong H850 WAA helping to push
temperatures into the upper 40s north to the upper 50s south. Made
minimal changes to the going max temp forecast given the possibility
of increasing cirrus cloud cover and the going forecast already on
the upper end of the guidance envelope. Increased sky cover over the
northern 2/3rds of the CWA for today and into this evening given the
influx of cirrus cresting the H500 ridge over the western High
Plains on IR imagery. NAM/RAP/GFS vertical RH cross-sections all
hold the cirrus into the early afternoon hours, though there are
some timing differences in the clearing of the clouds with the RAP
in particular holding the clouds well after sunset in the NE.
Tonight will be quiet weather-wise with increasing high clouds
streaming in from the SW towards sunrise ahead of our Sunday rain
event.
.LONG TERM.../Sunday through Friday/
Issued at 351 AM CST Sat Nov 26 2016
Vigorous short wave energy will cross over the Rockies early
Sunday with strong lee side cyclogenesis occurring from eastern
Colorado and into Nebraska. The deepening sfc low will lead to
strong moisture advection streaming north from the Gulf of Mexico
and into Iowa. Profiles will start the day quite dry but will
saturate quickly. As profiles saturate the mid level lapse rates
will steepen and weak MUCAPEs will develop. Thus expect elevated
thunderstorms to develop during the day. Showers and a few
thunderstorms may linger into early Sunday evening then subsidence
in the wake of the passing PV anomaly will arrive along with a
return of drier mid level air. The near surface moisture will
remain along with some turbulence and vertical ascent and this may
result in drizzle development.
The upper level energy will evolve into a deepening upper low
pressure that will slow and linger over the Dakotas on Monday then
move slowly east into Minnesota on Tuesday before eventually
reaching the mid Great Lakes on Thursday. How long clouds linger
on Monday is the main challenge for the temperature forecast. If
the clouds scatter, mixing will push high temperatures back into
the mid to upper 50s for central and southern Iowa. The primary
push of cold advection arrives late Monday afternoon and into the
overnight then 850 mb temperatures will continue to cool as the
upper low progresses east. The 850 mb temperatures will be near
-8C by Thursday. Mixing during this time will keep highs in the
30s to 40s with overnight lows generally in the 20s. Light rain or
snow will be possible over northern Iowa Tuesday into Wednesday
with little to no accumulations expected. The remainder of the
extended forecast will be mainly dry.
&&
.AVIATION.../For the 12Z TAFS through 12Z Sunday morning/
Issued at 538 AM CST Sat Nov 26 2016
VFR conditions are expected through the period with 30-40 kts of
LLWS over northern and western Iowa dissipating by 15Z. Afternoon
wind gusts today may reach 20-25 kts out of the SSW over the
southern half of Iowa.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Skow
LONG TERM...Donavon
AVIATION...Skow
Area Forecast Discussion
National Weather Service Lincoln IL
949 AM CST Sat Nov 26 2016
.UPDATE...
Issued at 949 AM CST Sat Nov 26 2016
CWA counties along the Indiana border still struggling to clear
out this morning, but RAP 925-850 mb humidity plots suggest some
improvement is imminent, and latest visible satellite imagery does
show some erosion taking place in the last hour. Further
northwest, some low clouds and dense fog formed over the Peoria
metro northeast along the Illinois River valley a few hours ago,
but recent observations at Peoria and Lacon are back up over a
mile and the low clouds will erode soon. However, cirrus clouds
are quickly streaming in from the northwest and will dim the sun
at times today, but skies overall should be mostly sunny. Forecast
grids were updated recently, and zone updates will soon follow.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 332 AM CST Sat Nov 26 2016
Low clouds have been slow to move out of central and southeast
Illinois, with low level moisture trapped beneath a strong
subsidence inversion. However, satellite loops suggest the back edge
of the clouds is continuing to make steady progress east over the
last several hours (although slower than any model solution). With
this in mind, have largely used satellite extrapolation to time
clearing today, which should have low cloud deck entirely east of
the area by early afternoon.
Otherwise, neutral upper-level flow and surface high pressure will
keep quiet weather conditions across the region through the period.
Temperatures will trend milder, climbing a little above normal
today, as low-level flow turns more southerly and increases on the
back side of the surface ridging.
.LONG TERM...(Sunday through Friday)
ISSUED AT 332 AM CST Sat Nov 26 2016
Upper level ridge over the MS river valley at sunrise Sunday, will
shift east over IL by 18Z/noon on Sunday and into the Ohio river
valley by 6 pm Sunday. Meanwhile surface high pressure ridge over
the Southeast States will drift toward the Carolina coast by sunset
Sunday. Expect clouds to increase from the west during the day
Sunday with a 20-30% chance of showers late Sunday afternoon west of
Peoria and Springfield as next storm system approaching the Prairie
State. Highs of 50-55F on Sunday as southerly winds pick up to
breezier levels by Sunday afternoon. The mildest readings near 55F
will be from Jacksonville sw and from Lawrenceville south.
A vigorous upper level troff off the West Coast will develop a
strong cutoff low over the eastern Dakotas by 12Z/Mon while surface
low pressure over eastern CO at sunrise Sunday ejects northeast to
near the eastern SD/ND border by 12Z/Mon. A widespread band of rain
showers will spread east across IL during Sunday evening, reaching
the Wabash river valley early overnight Sunday night. Rain showers
become less numerous Monday morning especially nw half of CWA, then
will see another increase in showers and isolated thunderstorms
during Monday afternoon and Monday evening, before diminishing
quickly from the west overnight Monday night. Rainfall amounts to
average around 1 inch with 1.25 inches in southeast IL. Rather
strong southerly winds on Monday into Monday evening helping pump in
deeper gulf moisture into IL. SPC day3 outlook has general risk of
thunderstorms across IL Mon afternoon/evening while marginal risk of
severe storms is sw of IL over southern MO into AR and slight risk
of severe storms over Louisiana and east Texas where better
instability will be. Lows Sunday night of 40-45F, Highs Monday in
the low to mid 50s, Lows Monday night in the low to mid 40s (mildest
readings in eastern IL).
Skies to become partly to mostly sunny by midday Tue as low pressure
moves into northeast MN. Fairly mild highs on Tue ranging from lower
50s nw of IL river to 55-60F over southeast IL. An upper level trof
then deepens into the Great Lakes and IL by Wed/Thu cooling temps
closer to normal and to bring more low cloud cover especially
northern CWA from I-74 north. 00Z models have trended further
southeast with qpf for Wed afternoon/evening and now our CWA appears
to stay dry with most of the qpf southeast of the Ohio river. Dry
weather with seasonable temps expected late next week with
precipitation chances confined to the Great Lakes region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 553 AM CST Sat Nov 26 2016
Aside from patchy fog over the next couple of hours, VFR
conditions will prevail across the central Illinois terminals
through the 12Z TAF valid time. High pressure and the associated
dry air mass will support minimal cloud cover. Winds will
gradually turn southwest and increase in speed as the ridge of
high pressure pushes east of the area.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Bak
LONG TERM...07
AVIATION...Bak
Area Forecast Discussion
National Weather Service Miami FL
1000 AM EST Sat Nov 26 2016
.UPDATE...
Scattered showers, mostly stationary, remain over the offshore
Atlantic waters, with only a few sprinkles seen on radar over
coastal locations from North Miami Beach to Princeton. Otherwise,
mainly benign weather conditons should continue through this
afternoon, although a brief passing shower or two can not be ruled
out. Afternoon highs will remain in the lower 80s in most locations
across South Florida with some periods of increasing cloud cover.
&&
.PREV DISCUSSION... /issued 719 AM EST Sat Nov 26 2016/
AVIATION...
Light wind will begin to increase up to around 10 kts this
morning, and turn northeast,as high pressure to the east weakens
ahead of an approaching cold front. The front will be weak, and
South Florida looks to be just on the tail edge of the front by
Sunday morning. This will keep most of the shower activity along
the coast, to just offshore, through tomorrow. So, some brief,
isolated showers will be possible, with VFR conditions forecast,
through the TAF period.
PREV DISCUSSION... /issued 429 AM EST Sat Nov 26 2016/
DISCUSSION...
A few brief showers have pushed westward across the
east coast metro region this morning from the Atlantic waters.
Otherwise, the radar was been relatively quiet. Last nights 00Z MFL
sounding showed a moderately moist layer from the surface up to
around 850 mb, with dry air aloft. Through early this morning, as
the boundary layer remains decoupled and temperatures drop,
patchy fog may develop across the interior. A weak cold front
will push southward down the north/central portion of Florida
during the afternoon. Ahead of this feature, a minor rise in
moisture and instability will lead to a slight chance of showers
over the Atlantic waters and immediate east coast region. Not
expecting much accumulation out of these showers, as the latest
HRRR and WRF model runs depict only spotty activity. On Sunday,
as the front advects south of the region, winds will shift to a
more northeast direction. Dry weather will generally prevail
through mid week, behind the frontal passage, as a ridge of high
pressure draws near. This ridge will allow for the flow to become
east/southeast and breezy at times with a tightening pressure
gradient, along with increasing low- level moisture.
The front passage will also act to lower temperatures across the
region. Maximum temperatures Sunday and Monday are only forecast
to top out in the upper 70s along the immediate east coast to
around 80 degrees elsewhere. Pressure increases aloft on Tuesday
and Wednesday should allow for temperatures to rise to the low 80s
along the east coast metro and up to the mid 80s inland. By
Thursday, temperatures may peak from 85 to around 87 degrees over
western sections of the interior. These values are over 5 degrees
warmer than normal for this time of year.
By late Thursday, the 00Z GFS progs another weak front to press
southward across the region. This feature should once again produce
enough lift and instability to generate a few showers over south
Florida, before exiting the area on Friday.
MARINE...
The flow will shift to a northerly direction today at generally
around 10 knots as a weak frontal boundary crosses the region. The
flow will increase and become east/southeasterly early next week
as high pressure reestablishes itself to the north of the region.
Scattered showers are possible today into Sunday associated with
the passing frontal boundary. Drier weather will return behind the
frontal passage early next week. Seas will be 4 feet or less
through early Sunday, increasing to 5-7 feet over the Gulf Stream
late Sunday into early Monday.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 82 65 78 70 / 20 30 20 10
Fort Lauderdale 82 68 79 70 / 20 30 20 10
Miami 83 66 80 69 / 20 30 20 10
Naples 81 62 80 63 / 10 10 0 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
UPDATE...17/AR
ZCZC WRKAFDMFL 000
TTAA00 KWRK 261041
!--not sent--!
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
933 AM CST Sat Nov 26 2016
.UPDATE...
Removed fog/freezing fog mention this morning. Lowered today`s
highs slightly across western north Texas and southeastern
Oklahoma. Adjusted sky cover today.
&&
.DISCUSSION...
Dry weather can be expected today with temperatures not too far
from seasonable averages.
Any fog appeared to be dissipating and was confined to locations
mainly southeast of a Seminole to Ada to Ardmore line as of 915 am
according to latest observations and visible satellite imagery.
This fog will continue to erode due to daytime heating, though low
clouds in these areas may be slow to erode and could keep
temperatures from climbing as high as previously forecast. Thus,
adjusted afternoon highs downwards in these locations.
Additional clouds were occurring across far southwestern Oklahoma
and western north Texas. These clouds may spread northeast during
the afternoon. A few echoes were detected by KFDR radar near Knox
City, Texas around 8 am this morning, but these did not appear to
be reaching the ground and have dissipated. These clouds may keep
afternoon highs down a bit as well.
Products have been updated.
MBS
&&
.PREV DISCUSSION... /issued 517 AM CST Sat Nov 26 2016/
DISCUSSION...
12Z TAFs.
AVIATION...
Visibilities have been reduced in fog and freezing fog across
northeastern Oklahoma. Although this fog has not developed
significantly in the forecast area, there are hints of patchy
ground fog. The fog/freezing fog will be possible at KPNC and have
kept a TEMPO group with 3SM BR there this morning. It certainly is
possible to see more significant fog at KPNC, but the probability
is low enough to not include in the 12Z TAFs. Otherwise, a windy
day is expected today with generally VFR conditions expected this
afternoon. MVFR to possibly IFR ceilings will likely redevelop
overnight.
PREV DISCUSSION... /issued 442 AM CST Sat Nov 26 2016/
DISCUSSION...
Although the fog and freezing fog has been slow to develop very
far west yet, there are some low visibilities across northeast
Oklahoma and the HRRR is still somewhat aggressive in fog
formation across the far northeastern portions of the forecast
area through sunrise. At this time, we will let the freezing fog
advisory continue where it is currently located and continue to
watch the trends. Farther south, a weak wave over Texas continues
to spread showers east to the south of the forecast area. The best
signal is for the precipitation to remain to the south today.
The next significant precipitation chances will be on Sunday and
Monday. One mid-level trough moves northeast from the
southwestern U.S. into the central Plains Sunday with another
trough developing in the southwest and moving over the southern
Plains on Monday. Cooler air will filter into the area next week
behind these systems.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 62 49 65 50 / 0 0 40 30
Hobart OK 60 50 68 45 / 0 10 30 20
Wichita Falls TX 60 51 70 53 / 10 0 30 30
Gage OK 65 49 68 38 / 0 0 40 0
Ponca City OK 61 46 65 50 / 0 0 50 30
Durant OK 60 49 67 58 / 10 0 40 70
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
17/12
Area Forecast Discussion...UPDATED
National Weather Service Portland Oregon
628 AM PST Sat Nov 26 2016
Updated Marine Section
.SYNOPSIS...After a brief break for much of NW Oregon and some of SW
Washington, rain is expected to resume today as an elongated area of
low pressure is pushed inland by a strong Gulf of Alaska cold front.
Snow levels are starting off above the Cascade passes this morning,
but will lower dramatically this afternoon and evening as cool west
to northwest flow develops across the region. Strong onshore flow
will bring plenty of showers through Monday night. Snow will pile up
in the Cascades in cool and moist upslope flow; areas above 4000`
elevation may see a foot or more by Monday. High pressure may bring a
brief break Tuesday, with the next system likely to bring more valley
rain and mountain snow showers Wednesday.
&&
.SHORT TERM...Today through Monday...Another busy night here at the
weather office with numerous warnings, watches, and advisories in
place for the next few days. A handful of rivers remain above flood
stage from our heavy Thanksgiving rain. As of 5 AM, the Marys,
Luckiamute, and South Yamhill Rivers were still above flood stage.
However, all are expected to drop below flood stage by tonight.
The greater concern, especially for travelers, is the heavy snow that
is expected in the Cascades. For the time being, conditions are
benign this morning as the 12z Salem sounding reported a freezing
level of 7200 feet and the Cascade passes are generally wet. However
things will be changing quickly this afternoon and evening as an
impressive W-NW`ly jet stream aims toward the Pac NW and advects
increasingly cooler air into the region. Two periods of moderate to
heavy snow are possible in our Cascades; the first being tonight for
primarily the Lane County Cascades, and the second being Sunday night
into Monday for the S WA Cascades down to the Lane County Cascades.
By the time all is said and done Monday, some of the higher ski
resort elevations could have upwards of 2 feet of new snow, while the
passes get 8 to 16 inches.
The weather pattern starts out complex today with an elongated area
of low pressure just off much of the U.S. West Coast. Given that
there are multiple low pressure centers embedded within, it is not a
surprise that even the shorter-range models are struggling with how
this pattern evolves today. The 00z WRF-GFS 4km run was a bit
alarming in bringing a low - presently just offshore the OR/CA border
- NE through the forecast area as a sub-1000 mb low. This solution
was suggesting advisory-level winds (40-50 mph gusts) possible in the
Willamette Valley south of Salem...with some semblance of the 2002
"Surprise" Eugene windstorm. However, infrared satellite has shown no
indication of the low turning NE yet, and the last couple runs of the
HRRR (10z and 11z) have the low drifting east along the OR/CA border
as a rather uneventful open wave. So, while we will have to watch
this low closely, we opted against mentioning much wind associated
with the low.
Despite the low opening up and weakening while moving onshore, even
the less aggressive models still bring plenty of precipitation to
Lane County today/tonight associated with this system. Combination of
strengthening frontogenesis and good jet dynamics, along with
lowering snow levels due to wet-bulb effect, and simply cold air
advecting in from the Gulf of Alaska on a 130-150 kt jet, should
result in enough QPF and cold air to warrant a Winter Wx Advisory for
4-9 inches of snow in the Lane County Cascades tonight. The heavier
snow may extend further north than Lane County, but confidence was
not high enough to issue an advisory as far north as Santiam
Pass...but future shifts will need to monitor this.
As the mean upper ridge position continues to retrograde west into
the Pacific, strong W-NW flow will take aim at the Pac NW. This will
guide a series of disturbances across the Cascades beginning Sunday
afternoon, while strong westerly/upslope flow at 850 mb (35-45 kt at
times) will be extremely efficient at enhancing precip in the
Cascades. For most of the forecast area, this pattern will just be a
cool and showery pattern through Monday. However, in the Cascades,
the strong orographics will set up a classic Pac NW snowbuilding
pattern. Models often underdo QPF in this type of pattern, especially
the lower resolution models...as they cannot fully resolve the
Cascades. However, some of the higher resolution models like the 4km
WRF-GFS easily show 1-2 feet of snow in the Cascades above 4000-4500
feet...which seems entirely believable considering the very strong
upslope flow. Decided enough confidence is there for a Winter Storm
Watch for our Cascades Sunday night and Monday - despite lower
resolution models holding back some on QPF.
Travelers planning to head across the Cascades should probably have a
backup plan this weekend. The period of most concern is Sunday night,
when snowfall rates will probably be up to 2 inches per hour at
times. Winds will be very strong at the ski resort elevations - with
gusts possibly as high as 100 mph on some of our higher elevation
wind sensors. At pass level, gusts 30-50 mph will be possible, which
would create whiteout or occasional blizzard conditions Sunday night
into early Monday. This is the type of setup that has been somewhat
absent the last couple years, so travelers may not be used to how
quickly conditions can turn for the worse in the Cascades.
Significantly better conditions are expected through the Columbia
Gorge, where temperatures will be well warm enough for rain instead
of snow...so travelers may want to consider alternate options other
than the Cascade passes this weekend. Weagle
.LONG TERM...No Changes. Previous discussion follows...
(Monday night through Friday)...Models remain in pretty good
agreement overall through the end of the week, with mainly minor
timing issues. Mon night and Tue a ridge moving across will bring an
end to the showers associated with the departing trough. Another
fairly strong shortwave and cold front arrives from the west Tue
night bringing another round of rain. With origins in the north
Pacific, snow levels will again drop down to pass levels or a little
lower. Showers follow late Tue night and slowly decrease Wed night
and Thu as ridging builds in from the west. After a brief break under
the ridge Thu night, another chance for rain moves in from the nw Fri
as the tail end of a warm front approaches off the Pacific.
&&
.AVIATION...Primarily VFR early this morning, but there are areas
of IFR or worse in the South Willamette Valley. Warm-frontal type
rain has spread to the South Washington and North Oregon coast as
of 0930Z, but conditions were still VFR. KHIO could lower into IFR
in the 10Z-12Z time frame.
Overall, coastal TAF sites to remain VFR through 13Z or so, with
KONP holding on to VFR a little longer. Conditions eventually
lower to MVFR by mid to late morning, followed by a mix of VFR
and MVFR through Sat evening. Inland TAF sites will be a little
more complicated, especially in the central and south interior
valleys. Areas of IFR or worse will persist in those areas through
at least 16Z, then expect predominant MVFR. Areas near the
west end of the Columbia Gorge to stay VFR through at least 19Z
due to offshore low-level flow. MVFR likely to form in the
afternoon as the offshore gradient weakens.
KPDX AND APPROACHES...VFR at the terminal and vicinity as of 10Z.
KTTD-KDLS gradient -4.2 mb at 09Z. Gradient should remain around
-4.0 mb through the morning, which will maintain east wind near
the west end of the Columbia Gorge. KPDX-KTTD gradient was 0.2 mb
and would expect it to hover near 0 mb through the morning for
southeast wind 5-10 kt. Thus, VFR to hold through at least the
morning. There may be some pockets of IFR or worse in the fog-
prone valleys west of the terminal. MVFR to develop late in the
morning and be the predominant category through the afternoon and
evening. Weishaar
&&
.MARINE...UPDATED...Significant changes to the forecast at 6 am.
Satellite imagery and 13Z HRRR MSLP plot clearly shows the primary
surface low about 75-100 nm west of Pt. St. George at 14Z.
Satellite imagery suggests the low center is slipping SE and not
heading north. The 13Z HRRR shows this low center drifting toward
the coast over the next few hours. HRRR surface wind gusts max out
around 25 kt this morning. Based on 14Z buoy obs, satellite trends
and HRRR guidance, have opted to cancel the gale warning and go
with small craft advisories for wind and seas. The wind portion
extends through 22Z. However, it looks like another advisory will
be needed for the south outer waters and possibly the far south
part of the north outer waters beginning early this evening.
Winds veer to the northwest behind the low pressure center as it
moves toward shore overnight this morning through the afternoon,
likely holding at small craft advisory speeds through late
afternoon. The lull will be brief as wind speeds are forecast to
strengthen from south to north this evening and tonight. Far south
waters could see gusts up to 35 kt. A stronger system moves
through the waters late Sun through Mon morning with possible gale
gusts Sun night through early Mon morning.
High pressure finally settles over the waters Mon night and Tue.
Models show another frontal system late Tue or Tue night, with the
ECMWF moving it through much faster than the GFS. In fact, the GFS
has a much tighter surface low and holds it over the waters late
Tue night through Wed night. Would tend to side with the ECMWF.
High pressure returns mid to late next week and is expected to
hold into next weekend.
Seas currently around 12 ft, but briefly fall just below 10 ft
across the majority of the waters by late this afternoon. Seas
hover around 10 ft through Sunday, but then large swell will push
seas into the middle to upper teens late Sunday night into Monday.
This larger swell train stems from a decaying low originating near
the Aleutian Islands. Seas remain in the middle to upper teens
through at least the first half of next week. Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Watch from Sunday afternoon through Monday
afternoon for Northern Oregon Cascades.
Winter Weather Advisory from 2 PM this afternoon to 10 AM PST
Sunday for Cascades in Lane County.
Winter Storm Watch from Sunday evening through Monday afternoon
for Cascades in Lane County.
WA...Winter Storm Watch from Sunday afternoon through Monday
afternoon for South Washington Cascades.
PZ...Small Craft Advisory for winds until 2 PM PST this afternoon
for Coastal Waters from Cape Shoalwater WA to Florence OR
out 60 nm.
Small Craft Advisory for hazardous seas until 4 PM PST Sunday
for Coastal Waters from Cape Shoalwater WA to Florence OR
out 60 nm.
Small Craft Advisory for Rough Columbia River Bar from 1 PM to
5 PM PST this afternoon.
Small Craft Advisory for Rough Columbia River Bar from 1 AM to
5 AM PST Sunday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.
Area Forecast Discussion
National Weather Service Reno NV
337 AM PST Sat Nov 26 2016
.SYNOPSIS...
The next system will bring gusty winds today for eastern CA and
portions of western NV, with Sierra snowfall beginning late this
afternoon and evening. A colder system will bring heavier snow
for the Sierra late tonight and Sunday morning with light to
moderate snow also developing for western NV valleys. Another
round of light snow is possible late Sunday night.
&&
.SHORT TERM...
Additional winter weather advisories were hoisted for west
central NV tonight and Sunday and precipitation chances were
raised for late tonight. The forecast remains generally on track
for a weak, elongated trough for this afternoon and evening
followed by a more potent hybrid slider-type system for late
tonight and Sunday morning.
Wind-wise today, the wind advisories for portions of northeast CA
and far northwest NV, as well as Mono County, have been cancelled.
It will still be breezy by late morning and for the afternoon but
widespread wind gusts over 45 mph are not expected in the above
areas.
Areas which still have wind advisories today are the Lake Tahoe
Basin and Reno-Carson City-Minden areas. With the southerly flow
aloft through much of the day, the South Lake Tahoe area and
southern part of Lake Tahoe should mix down a good percentage of
the 50-60 mph gusts currently blowing over the northern Sierra
ridges, especially as the thermal gradient intensifies ahead of
the incoming precipitation band this afternoon. For far western
NV, most areas will likely see wind gusts in the 35-40 mph range
today but some areas should see gusts closer to 50 mph...with the
HRRR simulations showing the higher gusts in the Carson Valley, in
the foothills southwest of Reno, and along highway 395 in the
North Valleys.
After the weak trough axis swings through late this afternoon and
evening and brings some light snow mainly to the Sierra, attention
turns fully to the incoming hybrid slider system (currently west
of British Columbia per IR/WV satellite) for late tonight and
Sunday morning. As it will briefly reside off the Pac NW coast,
it still looks to pick up a little extra moisture, and is more of
a hybrid slider than a straight inside slider-type disturbance.
With the extra moisture, the Sierra is expected to get a bit more
snow than most of western NV rather than getting the same or less
snowfall as western NV as happens with inside sliders.
As far as snowfall amounts, a solid 1 to 3 inches is a good bet
for western and west-central NV with higher amounts possible in
local areas. The entire west-central NV Basin and Range has been
added to the snow advisories as no one area looks more favorable
for a light snowfall than another...which is typical for sliders.
Note that GFS/NAM simulations are showing a distinct gap in
precipitation for far western NV. However, it is believed that
this is just the usual dry bias in the lee of the Sierra when
models show strong westerly flow at around 700 mb. Sounding
profiles, instability, and forcing are quite sufficient to bring
easy spillover despite the flow aloft.
By around midday Sunday, models show the slider shoving quickly
off into central and southern NV for an abrupt end to snow.
However, quick on the heels of the slider is another wave moving
down from the Pac NW in swift northwest flow aloft. This should
bring a period of light snow to much of eastern CA and western NV
due to warm air advection later Sunday night and Monday morning.
Behind the wave on Monday, a reinforcement of colder air is
expected to keep highs below average with mid 30s to mid 40s for
Monday afternoon. Snyder
&&
.LONG TERM...Tuesday through Friday...
Shortwave ridge will be moving into the area Tuesday. After a cold
start, temperatures in the valleys will struggle to rise as warmer
air aloft/inversions develop. Mixing and ventilation will be
limited for prescribed burning operations as winds will be
lighter.
For Wed-Fri, medium range models are coming into better agreement
with ridge building into the Pacific Northwest. This would result in
a positively tilted longwave trough extending from the desert
southwest into the northern plains by the end of the week/next
weekend. As trough drops through the Great Basin, there will be a
chance of snow showers mainly Wed night into Thursday although
northeast upslope flow on backside of trough may keep some light
snow going along the eastern Sierra through Friday. Right now,
snowfall amounts look pretty light and generally under an inch.
Confidence is much higher on cold temperatures for the end of the
week as north to northeast flow and 700MB temps around -10C to -14C
keep daytime highs from getting out of the 30s to lower 40s Thu-Fri
even with little or no snow cover. Hohmann
&&
.AVIATION...
Gusty winds will continue today and tonight ahead of incoming trough
with mostly unidirectional south to southwest flow through the lower
levels. This should limit LLWS except for a brief period this
morning while surface winds remain light in the lower elevation
terminals. Turbulence will likely be moderate at times as ridge
wind gusts approach 80-90 kts. Surface winds were already blowing
in the Tahoe Basin but should pick up later this morning and
spread to the Hwy 395 corridor this afternoon. Wind gusts will
mostly be 30-35 kts although a few gusts to 40-45 kts will be
possible, mainly in wind prone locations.
As far as snow potential, snow showers will reach the Sierra crest
this afternoon and hold there through this evening as they wait for
incoming trough to arrive. Snow will become moderate in the Sierra
this evening and then spill over into western NV overnight and early
Sunday morning. Snowfall amounts will be heaviest at the Tahoe TAF
sites where up to 8 inches are possible. Amounts for KMMH-KRNO-KCXP
and much of western NV will generally be 1-2 inches although a few
heavier bands of snow could deposit a quick 4 inches of snow. Due to
the cold airmass and time of day, the threat for accumulations on
runways is high. Snow will decrease from north to south late
Sunday morning and early Sunday afternoon with brisk northwest
winds gusting around 30 kts. Hohmann
&&
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 4 PM this afternoon to 10 AM PST
Sunday NVZ005.
Winter Weather Advisory from 4 PM this afternoon to 1 PM PST
Sunday NVZ002.
Wind Advisory until 4 PM PST this afternoon NVZ002.
Winter Weather Advisory from 4 AM to 1 PM PST Sunday NVZ001.
Winter Weather Advisory from 10 PM this evening to 1 PM PST
Sunday NVZ003-004.
Wind Advisory from 9 AM this morning to 4 PM PST this afternoon
NVZ003.
Lake Wind Advisory from 7 AM this morning to 6 PM PST this
evening for Pyramid Lake in NVZ004.
CA...Winter Weather Advisory from 4 PM this afternoon to 10 AM PST
Sunday CAZ070-071.
Winter Weather Advisory from 2 AM to 1 PM PST Sunday CAZ073.
Lake Wind Advisory until 4 AM PST early this morning for Lake
Tahoe in CAZ072.
Winter Weather Advisory from 4 PM this afternoon to 1 PM PST
Sunday CAZ072.
Wind Advisory until 4 PM PST this afternoon CAZ072.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service La Crosse WI
235 PM CST Sat Nov 26 2016
.SHORT TERM...(This evening through Sunday)
Issued at 235 PM CST Sat Nov 26 2016
Latest 20z surface analysis shows ridge over the Ohio River Valley.
Southerly winds on the backside of the surface ridge has ushered
in warmer temperatures into the forecast area today. Temperatures
have climbed into the middle 30s to lower 50s per latest metars.
For tonight, the NAM and RAP soundings continue to show a very
strong inversion will develop overnight. As a result, they are
developing fog and stratus across the area. The NAM is likely doing
this because it is assuming that our area currently has snow on the
ground. Meanwhile, the GFS soundings show that the boundary layer
will remain well mixed; thus, no fog or stratus development. For
the time being, kept the mention of patchy fog in western Wisconsin.
This will cover the possibility of fog developing in the shelteredareas
overnight and Sunday morning.
Another potential concern tonight is the low temperatures. The model
consensus has low temperatures ranging from the mid-20s to lower
30s. These temperatures seem just too cold considering the well-
mixed boundary layer and that the dew points are currently in the
mid-and upper 30s. Due to this, raised the low temperatures up into
the lower 30s. However I am a bit concerned that these low
temperatures may still be too cold.
With upper level trough digging over the western United States and
upper level ridge amplifying over the Great Lakes Region...southerly
winds aloft will continue to advect a warmer airmass into the
forecast area Sunday. The 26.12z GFS/NAM/ECMWF suggest 925mb
temperatures warming to plus 2 to plus 7 degrees celsius by 00z
Monday. Once again...temperatures will be well above
normal...with highs in the 40s and possibly the lower 50s.
.LONG TERM...(late Sunday afternoon through Saturday)
Issued at 235 PM CST Sat Nov 26 2016
The 26.12z GFS/NAM/ECMWF are in agreement in lifting upper level
closed low/shortwave trough into the Northern Plains States Sunday
night into Monday. The deterministic models indicate strong moisture
transport/converge and forcing in association with the upper level
closed low/shortwave trough. Increasing moisture/forcing will
produce a band of precipitation and move northward across the
forecast area late Sunday afternoon(after 21z Sunday) through Monday
morning. Rainfall amounts of a quarter to possibly three quarters
of an inch is expected Sunday night into Monday across the
forecast area. Next concern are thunderstorm chances...the 26.12z
GFS/NAM continue to show minimal elevated CAPE with the system.
However...with a dynamic system...cannot rule out an isolated
thunderstorm across the forecast area. Will continue mention of
isolated thunder.
Upper level low remains nearly stationary across northern Minnesota
Tuesday and main shortwave trough pushes into southern Ontario
Canada. This will move heavier precipitation over Lake Superior and
southern Ontario Canada. Forecast area may see some light
precipitation...as weak shortwave trough wraps around on the
backside of upper level low into western Minnesota. Precipitation
chances will remain small with light amounts.
Main forecast concerns from Tuesday night into Saturday are light
wintry precipitation chances through the period. The 26.12z
GFS/ECMWF/GEM are in good agreement in weakening or slowly moving
upper level closed low/trough over the northeastern United States
during the period. Main difference between the deterministic
26.12z models are timing the weak shortwave troughs rotating
around the upper level low/trough over the Great Lakes Region
through the period. Overall...the 26.12z GFS/ECMWF/GEM are in
decent agreement in wrapping weak shortwave troughs into the
region and will result in on and off small precipitation chances
through the period. Temperatures will be cooler and near
normal...as the 26.12z deterministic models advect a cooler
airmass into the forecast area on the backside of the upper level
low/trough. Highs are expected to be mainly in the 30s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1138 AM CST Sat Nov 26 2016
With diurnal mixing, the stronger winds from aloft will mix to the
surface. The sustained south winds will be in the 10 to 20 knot
range. These winds will decrease to less than 10 knots tonight...
and then once again increase into the 10 to 20 knot range after
27.15z.
While some of the guidance suggests the development of widespread
fog overnight and Sunday morning, thinking that the boundary layer
will remain mixed enough that this will not occur.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DTJ/Boyne
LONG TERM...DTJ
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Sioux Falls SD
254 PM CST Sat Nov 26 2016
.SHORT TERM...(This evening through Sunday)
Issued at 254 PM CST Sat Nov 26 2016
Very light flow across the area will continue through the early
evening hours. Easterly flow will develop and strengthen towards
06Z. Nam, RAP and HRRR all show low level saturation developing, and
the potential of fog along and east of the James. GFS is much drier
in the low levels, and fails to saturate. Cross over temperature is
in the mid and upper 30s across the region, and with forecasted lows
in the upper 20s and lower 30s, the technique would suggest fog
potential, so have discounted GFS. HRRR and RAP to an extent have
delayed the onset of fog through the afternoon, but still are
forecasting widespread dense fog by early Sunday morning. If this
occurs, will be difficult to get rid of the stratus tomorrow morning
as easterly flow strengthens and moisture flux increases ahead of an
approaching wave from the southwest.
As the initial wave of the upper trough lifts northeast through the
area, expect a band of showers to lift from the southwest to the
northeast. A minor amount of CAPE exists along and east of the
James River, so could see a lightning strike or two. High
temperatures in the east could be held down some on Sunday by
lingering fog and stratus and by shower activity in the afternoon.
.LONG TERM...(Sunday night through Saturday)
Issued at 254 PM CST Sat Nov 26 2016
The cold front aloft swings north quickly on Sunday night and still
indications for enough instability that we could here a few rumbles
of thunder. The dry slot races north through the evening which
should shut down precipitation coverage and may introduce a little
drizzle. Lowest levels not saturated enough to introduce but
something that may need to be added. Overall should be pretty much
rain with some small threat for light snow along and west of the
James River Valley.
Monday will be mild as westerly flow develops, and this will
actually be the pattern that develops through mid week. The only
difference will be a very gradually shift to a more northwesterly
flow and slightly cooler low level air building in. But overall
Monday through Wednesday will see breezy west to northwest winds,
temperatures in the 30s, a little warmer Monday, and scattered
showers with the cold pocket aloft. On monday a few of these showers
will likely remain rain showers, but Monday night into Wednesday
evening the most likely precipitation type will be snow as the warm
layer is very shallow.
Thursday through Saturday looks dry with a sustained chilly period.
Northwest winds will diminish through this period but highs will
remain in the 30s with lows in the 20s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1142 AM CST Sat Nov 26 2016
VFR conditions expected this afternoon. As flow goes light tonight,
models suggest low clouds and fog expanding from the north and
east into the forecast area. Areas east of I-29 appear to be a
fairly good bet to see IFR or lower conditions developing. Areas
further to the west are more questionable. Have introduced low
clouds and reduced visibility into the forecast, but visibilities
maybe lower than currently forecast.
Low clouds and fog will struggle to erode on Sunday with easterly
flow developing ahead of the next wave approaching.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...BT
LONG TERM...08
AVIATION...BT
Area Forecast Discussion
National Weather Service Gray ME
516 PM EST Sat Nov 26 2016
.SYNOPSIS...
A trough of low pressure will linger over the region tonight and
Sunday. A narrow ridge of high pressure will build in from the
west Sunday night and Monday. High pressure will shift off to the
east Monday night. A warm front will approach from the southwest
on Tuesday and will stall over southern New England on Wednesday.
Low pressure will develop over the mid Atlantic coast Wednesday
night and will move northeast along the New England coast on
Thursday. Low pressure will continue northeast into the maritimes
Thursday night. A trough of low pressure will remain over the
area on Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
---515pm Update---
Quick update this afternoon to better account for the
precipitation moving through southern New Hampshire and southern
Maine. 20Z HRRR has a very good handle on this feature and have
relied on it to better time the precipitation moving through this
evening. Otherwise...rest of the package remains largely
unchanged.
/.Previous Discussion.../
Showers ahead of trough axis currently lifting northeast through
southern New Hampshire this afternoon and expect this
precipitation to fade as it continues northeast into southwest
maine through the remainder of the afternoon. Trough axis will
shift eastward into central Maine this evening and will be the
focus for a variety of precipitation overnight and Sunday. In far
northeast zones looking for occcasional light snow to develop
after midnight with an inch or two possible by morning in central
Somerset County. As colder air filters southward may see rain in
in east central zones go over to snow with some light
accumulations...generally less than a inch. Remainder of the
forecast area will see a mostly cloudy night with patchy fog. Lows
overnight will range from the upper 20s to mid 30s.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Precipitation will wind down in far eastern zones on Sunday with
little if any additional accumulations of snow or qpf. Remainder
of the forecast area will see a mostly cloudy day with some sunny
breaks in southwest zones and a chance of snow showers in the
mountains. Highs on Sunday will range from the mid 30s north to
the lower 40s south.
High pressure will build in from the west Sunday night bringing
diminishing clouds overnight. Will see a chance of evening snow
showers in the mountains before clouds diminish after midnight.
Lows will be in the lower to mid 20s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High pressure builds across the region Monday but quickly moves
offshore by Tuesday. Models all showing a strong short wave moving
northeast toward New England Tuesday afternoon with an associated
warm air advection pattern spreading overrunning precipitation
Tuesday afternoon and Tuesday night across the forecast area. A
deep upper trough over the Great Lakes midweek will continue a
moist southwest flow Wednesday. On Thursday a strong short wave
rotates around the base of the Great Lakes upper trough and
swings northeast toward the Northeast developing a coastal low
that will bring rain to the area Thursday. The system will exit
into the maritimes Thursday night. The upper trough over the
Great Lakes moves east through the area Friday into Saturday with
colder air and scattered snow showers mainly in the mountains.
Considering the fast moving active pattern used the superblend
model and didn`t deviate from the pops and temps for the outlook
period.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
Short Term...areas of ifr/lifr ceilings and vsby overnight and
early Sunday. Becoming VFR on Sunday with areas of MVFR ceilings
in the north and central Maine zones.
Long Term...VFR Monday into Tuesday morning. Expect widespread
MVFR/IFR conditions late Tuesday through Thursday.
&&
.MARINE...
Short Term...SCA`s late tonight through Sunday.
Long Term...A series of low pressure systems will track near the
Gulf of Maine midweek, and each of them will have the potential to
bring stronger winds to the area.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 4 AM to 7 PM EST Sunday for ANZ150-
152-154.
&&
$$
Pohl
Area Forecast Discussion
National Weather Service Lincoln IL
211 PM CST Sat Nov 26 2016
.SHORT TERM...(This evening through Sunday)
ISSUED AT 211 PM CST Sat Nov 26 2016
Some welcome sunshine is occurring across much of the forecast area
this afternoon. The exception is over the northeast corner, where
diurnal cumulus started forming around midday from Decatur eastward.
While the western fringes have quickly faded, the clouds have been
tougher to exit areas around Champaign and Danville. Temperatures
over most areas had reached the 50 degree vicinity by 1 pm.
Surface ridge will continue to slowly shift eastward across the Ohio
Valley tonight, and southerly winds will keep temperatures up as a
result, mainly in the mid 30s over the CWA. Main question will be
for any fog development. Both the NAM and RAP soundings are showing
very moist profiles below 970 mb with dry air above it, with its
visibilities (and the associated HRRR) tanking overnight. Meanwhile,
the the GFS soundings are indicative of more mixing of the boundary
layer during the day, and only reduce visibility to around 3-4
miles. Leaning more toward the GFS scenario at the moment, but will
include mention of patchy fog after midnight over the area.
The storm system over the Plains will start cranking up quickly on
Sunday as the deep upper trough currently coming onto the California
coast ejects northeast overnight. While clouds will steadily
increase, it still looks like most of the daylight hours will be dry
in central Illinois. Have limited most of the PoP`s to the far west,
with slight chances as far east as Springfield and Peoria.
Temperatures expected to reach the lower 50s again despite the
clouds, as the southerly winds ramp up.
&&
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 211 PM CST Sat Nov 26 2016
Precip will be spreading across most of the CWA Sunday night as the
low pressure area in the northern plains continues to deepen and
move further north. This period of precip Sunday night will be the
first of two waves of precip to move across the area. Probabilities
of moderate showers with this first wave will be quite high and qpf
during the 12hr period will be near one half inch, with the highest
amounts being north of I-72. There will be a lull after this wave as
the main cold front will still be lagging back to the west during
the day Monday morning. The highest pops during the morning will be
in the south and southeast as this will be where any lingering
precip associated with the first wave should be. Pops will increase
again during the afternoon as the second wave moves northeast into
the eastern half of the CWA, mainly east of I-55. There should be a
good amount of instability in the area, given the amount of warm and
moist air that should be advecting into the area ahead of the
system. So, this wave will bring showers and isolated thunderstorms
to the area Monday afternoon through Monday evening, with the best
chance of thunder being associated with the best instability, Monday
evening. QPF will be higher with the second wave and all models now
agree that the axis of heaviest qpf should be across the
southeastern portions of the CWA, where qpf values should exceed one
inch. The main front of this system will move through the CWA Monday
evening, but showers will still be possible during the overnight
hours as a mid level trough rotates through the area. Winds will be
southeast ahead of the system and will be breezy/gusty due to the
tight surface pressure gradient and strong low level winds...even
during the Sunday night time frame. Speeds will begin to taper off
once the precip moves through the area later Monday night. Beginning
Wednesday, and through the remainder of the forecast period, surface
winds will be westerly with winds not very strong.
By Tuesday morning, the front and associated weather will be well
northeast and east of the area, so dry weather can be expected into
the middle of the week. The mid level low pressure area associated
with the surface system will remain in the western Great Lakes
region, keeping the CWA under some cyclonic flow aloft. As the upper
level system finally moves east during the middle of the week,
partly to mostly cloudy skies will be possible, but no precip is
expected at this time. Surface high pressure will finally build into
the region for the end of the week and into next weekend, while the
mid levels transition into a two stream setup, with one upper level
low in the southwestern US and the other over the Great Lakes.
Temperatures will be quite warm through Monday night, due to the
strong warm air advection forecasted ahead of the weather system.
The cold air looks to lag quite a bit behind the precip, so Tuesday
should be above normal as well. The cooler, below normal, air looks
to hold off until the latter part of the week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1137 AM CST Sat Nov 26 2016
Earlier dense fog/low clouds at KPIA has lifted and most of the
lower clouds in eastern Illinois have moved out as well, but some
recent MVFR conditions have developed near KCMI. Not expecting
this to last long, but will include a couple hour TEMPO period for
it. Later on, main question becomes with redevelopment of fog
overnight. NAM-based guidance is hitting it pretty hard, but has a
much deeper low-level moisture profile on forecast soundings. Have
some concerns this is overdoing it given the available sunshine
today, but will go with widespread visibilities around 4SM late
tonight and early Sunday morning. Any fog should lift by mid
morning as the gradient increases ahead of the next storm system.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Geelhart
LONG TERM...Auten
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
250 PM CST Sat Nov 26 2016
.SHORT TERM...
248 PM CST
Through Sunday...
Lower clouds are slowly exiting the area from west to east,
bringing the welcome return of at least partial sunshine. Breezy
southwest winds behind departing high pressure and approaching low
pressure across the plains have allowed temps to reach the mid to
upper 40s in most locations.
Conditions remain fairly quiet tonight into Sunday as the pressure
pattern does not change much. Our surface high pressure will move
from the Ohio Valley to the Appalachians and near the Atlantic
seaboard, while our existing low across the plains washes out and
we await the arrival of stronger low pressure that will result
from the deep upper trough in the west. The main question will be
the extent of any lower cloud cover or fog that several high
resolution short term guidance sources suggest later tonight into
early Sunday. Suspect some of this guidance is overdone and that
this would be a patchy fog and more a low stratus situation
suggested by the LAMP/NAM MOS. Dense fog would not be favored with
the winds staying up.
Otherwise expect increasingly breezy south winds turning
southeasterly through the afternoon. A lead shortwave ahead of the
trough attempts to create a shower or some sprinkles in our far
western areas, but most areas remain dry with increasing clouds
and highs in the mid to upper 40s, with some 50s expected
especially south as the thermal ridge axis approaches in spite
of clouds that will thicken through the day. Any stratus that
forms would delay the warming/inhibit reaching the higher numbers
if it sticks around.
KMD
&&
.LONG TERM...
242 PM CST
Sunday night through Saturday...
The main concern for the longer term forecast period will focus on
the development and impacts of a negatively tilted upper trough,
and associated sfc reflection lifting out of the central
Rockies.
The models are converging on a rather consistent solution with this
system, so forecast confidence in the impacts and timing of this
system is relatively high. By Sunday night, the main upper low
will lift into the nrn plains as the associated sfc low follows
suit, keeping the system vertically stacked. A the same time...sfc
high pressure will build off the mid Atlantic coast, setting up a
wide- open GLFMEX. With an extended period of warm, moist
advection, with pwats climbing to slightly above 1 inch, which is
very close to the 99th percentile, or more than 2 standard
deviations above seasonal normal levels. While storm total pcpn
should reach or exceed 1 inch areal average across the region, do
not expect a flooding threat with this system as pcpn is expected
to to fall over an extended period of time, with the moisture axis
steadily shifting east through the period as a secondary sfc
wave developing along the associated sfc cold front forces the
boundary to steadily shift east even when the vertically stacked
upper low remains parked over the nrn plains. With the extended
period or warm, moist advection, expect temps well into the 50s
for Monday and Tuesday while sfc dewpoints range from the middle
40s to arnd 50 F. The period with the greatest thunder threat will
be monday afternoon/evening as the secondary sfc wave along the
cold front tracks through the local area. Pcpn should shut off
relatively abruptly Tuesday morning as much drier air is wrapped
around the main upper low. A series of southern stream shortwaves
rotating arnd the srn/sern periphery of the upper low will keep
relatively mild conditions over the local area through Tuesday and
deep layer cold advection will not set until Wednesday as the
upper low finally begins to progress to the east. Wednesday should
be a transitional day, with temps still around the middle 40s, and
temperatures transition to below normal levels for Thursday and
into next weekend, with highs in the upper 30s to arnd 40 and lows
in the upper 20s. Another concern with this system will be strong
south winds developing in advance of the cold front with wind
gusts of 25-30 mph.
&&
.AVIATION...
For the 18Z TAFs...1147 AM CST...
A forecast frought with peril with regards to cigs/vis overnight
tonight, though based on some guidance and the current set of TAFs
things could be somewhat benign. Winds will not be a huge concern
with southwest winds of 10 kt or so holding through at least mid
morning Sunday. With low pressure approaching from the west,
expect winds to shift to southeasterly later morning and afternoon
and likely exceed 10 kt.
Current MVFR clouds are clearing slowly despite a modest southwest
wind in place. They should still clear but may take a bit longer
farther east. The concern shifts to overnight into Sunday.
GFS/GFSLamp point to benign conditions with passing high clouds
and maybe some patchy lower clouds, the NAM hits us with some MVFR
clouds, the RAP and HRRR show decent lower level saturation for at
least some lower MVFR/IFR clouds. The GLAMPMeld (blend of the
GLAMP/HRRR) takes a middle road of the two extremes and hits us
with some MVFR stratus, in line with the SREF and the conceptual
model of southwest flow warm advective lower cloud maintaining a
lower level inversion across the area. Tough to say how it will
play out at this point, but will introduce a scattered MVFR deck
for now. The low level inversion sits around 1000 ft initially so
it could come in IFR than lift a bit in the morning. Uncertainty
at this distance is rather high, but feel evening shift/early mid
shift will be able to get a better sense as to how the lower cloud
will materialize. The low level gradient and higher clouds keep
winds up so this is not a radiational fog setup though patchy fog
is possible in areas that decouple a bit more.
KMD
&&
.MARINE...
242 PM CST
Headlines...Will maintain the Gale Watch timing as currently
advertised, but will expand spatially to include the nearshore
waters from Northerly Island to Michigan City. No changes will be
made to the Gale Watch for the open waters. While a short period
of Small Craft Advisory criteria winds is likely before the
onset of gales, will likely transition to a Gale Warning as exact
timing becomes a bit more certain.
In the mean time, a ridge of high pressure is moving across
Lake Michigan this afternoon, bringing a period of relatively
light winds. The center of high pressure will reach the
Carolina coast by Sunday evening as deepening low pressure
lifts from the west-central plains to the eastern Dakotas. The
main sfc low will meander around the ern Dakotas/nwrn MN Sunday
night into Monday while a secondary sfc low develops along the sfc
cold front as it moves through the srn plains. The sfc pressure
gradient will strengthen rapidly as the secondary sfc low tracks
newd through the middle MS valley Sunday evening, with Gales
likely beginning early Sunday evening. Sely-sly gales should
persist through Monday evening, with the chance for gales to
persist into Tuesday morning as wind direction veers to swly. The
main question at this time is the end time of the Gale Warning,
with the possibility of swly gales persisting into late Tuesday
morning or even early Tuesday afternoon. Conditions should quiet
down over the lake Tuesday night and Wednesday as the main sfc
weakens and drifts across the upper Great Lakes.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Watch...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779...9 PM Sunday TO 3 AM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
214 PM CST Sat Nov 26 2016
.SHORT TERM...(This evening through Sunday)
Issued at 211 PM CST Sat Nov 26 2016
Subsidence from an upper ridge moving in from the Dakotas has
resulted in a gorgeous late November day...for most. This
subsidence has trapped some low level moisture and with weak surface
flow to help mix this moisture out, we have seen dense fog remain
across central MN, with another batch of mainly stratus over NW WI.
This central MN fog also coincides with where the greatest snow
cover remains from the blizzard back on the 18th. Even if we see
visibilities at places like Alexandria and Long Prairie improve to
the 2-4 mile range this afternoon, the continued light winds and
moist boundary layer will result in the rapid expansion of dense fog
in the area once again. As a result, have decided to issue a dense
fog advisory in central MN through the rest of tonight. We will
start with where the fog has remained overnight and will expand it
later if need be. Light winds will be in place pretty much area wide
with continued high low level moisture, so this fog will likely
expand overnight, though how far south and east it will build is in
question, which is why for now we have gone with a conservative
dense fog advisory area. Think the HRRR is likely overdoing its fog
depiction (as it did last night), but the SREF has probabilities for
visibilities less than 1 mile greater than 80% along and north of a
Redwood Falls/Twin Cities/Eau Claire line, which would be a good
boundary for the potential southern extent of any fog we see tonight.
Sunday, the deep trough currently coming onshore in California will
be working out into the Plains states. This will eventually lead to
cyclogenesis over Nebraska during the afternoon. Ahead of this
developing low, a significant surge of moisture will be rapidly
pushing north toward MN, with a band of isentropically forced
showers quickly approaching from the south. We will see the first
shots of rain moving into southwest MN around 21z, with the period
ending at 00z (6 pm Sunday evening) with a band of rain from west
central into south central MN that will quickly spread northeast
across the area Sunday evening. 850-500mb differential theta-e is
negative coming up Sunday afternoon on the NAM, indicating the
presence of some weak convective instability, so have a small
thunder mention coming up with the rain as well.
.LONG TERM...(Sunday night through Saturday)
Issued at 211 PM CST Sat Nov 26 2016
Precipitation will continue to overspread the area Sunday evening as
low pressure lifts north from the Nebraska/South Dakota border to
near the border of Minnesota and the Dakotas by 12Z Monday. The
model guidance is actually in good agreement on the track of the
surface low and upper level features through that time frame. As
that occurs, we`ll see rain overspread the area Sunday night, with
the dry slot working in by Monday morning. Still looks to be enough
elevated instability, per layer differential theta-e values of near
or below zero, for a mention of some thunder over most of the area
into Monday morning. Colder air will start to filter in from the
west Monday night, with lingering precipitation transitioning to
some light snow overnight into Tuesday morning. By that point, the
surface low will be slowly filling and should be located somewhere
over Minnesota. It will then move ever so slowly east over the next
couple days, eventually making it to the upper Great Lakes by
Thursday as a secondary low takes shape near New England. This will
result in a prolonged period of chance PoPs from Tuesday into
Thursday, with mainly light snow potential at night, and mainly
light rain or mixed potential during the daytime as temperatures get
back into the middle 30s each day. By Friday and Saturday we should
see sufficient dry air work into the region for things to dry out,
although enough low level moisture looks to linger for things to
remain mostly cloudy. Overall, will be a fairly gloomy week with
temperatures running a bit above normal, mainly due to lows that
will be well above normal.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1213 PM CST Sat Nov 26 2016
Fog is again the primary forecast concern. Where snowpack is
greatest in central MN, fog has been slow to budge and do not
think this is going anywhere today or tonight. AXN may see the
visibility increase to between 1 and 4 miles this afternoon, but
they will quickly fog back in. Also expect fog to develop again
tonight in western WI where winds will be lightest. There is
potential that fog could develop at RWF/MSP as well given moist
boundary layer and light winds, but will keep the fog mention to
near the snow and lightest winds. Sunday morning will see
increasing southeast winds as the next storm system approaches,
with rain moving into the terminals for the 00z TAF window.
KMSP...Only potential problem will be the treat for fog tonight.
Fog stayed out of MSP last night and expect the same tonight,
with the vis dropping down to 4 or 5 miles. Rain looks to arrive
shortly after 00z Mon, or just beyond the 30 hour window.
/OUTLOOK FOR KMSP/
Mon...MVFR early with -SHRA. Wind S 10-15 kts.
Tue...MVFR/IFR. Chc -RA. Wind SW 5-10 kts.
Wed...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Dense Fog Advisory until 9 AM CST Sunday for MNZ041>044-048>050.
&&
$$
SHORT TERM...MPG
LONG TERM...
AVIATION...MPG
Area Forecast Discussion
National Weather Service Morristown TN
326 PM EST Sat Nov 26 2016
.SHORT TERM (This Afternoon through Sunday)...
Skies have cleared out quickly over the last couple of hours with
mostly sunny skies now into NE TN and SW VA. However, temperatures
this afternoon are generally in the 40s/50s with northerly winds.
Current water vapor imagery and RAP upper air analysis indicates an
upper level trough along the Eastern Seaboard with a ridge across
the Great Plains. At the surface, high pressure is centered just
to the west and forecast to move through the area tonight.
PW values tonight are forecast to be in the 0.1-0.2 inch range.
These values are near the minimum observed for late November. The
combination of the dry airmass and surface high pressure overhead
will set the stage for ideal radiational cooling conditions tonight.
Lows tonight across the area will generally be in the mid to upper
20s but expect low 20s in the cooler locations.
Temperatures will warm quickly tomorrow with the dry airmass
remaining in place. Unfortunately, this will lead to elevated fire
danger across the area with RH values dropping down to 20-25
percent tomorrow afternoon. The good news is that winds will be
light from the southwest at around 5-10 mph at the most. With upper
level heights rising and mostly sunny skies on Sunday, high
temperatures will range from mid 50s to low 60s for most valley
locations.
.LONG TERM (Sunday night through Saturday)...
The main focus will continue to be on the big rain-maker during
the first half of the long term as well as high winds during the
initial trough approach.
On Sunday night...ridging still in place but slowly pushing east due
to incoming system. Southerly flow will allow for low temps to be a
few degrees above normal, mid to upper 30s north and lower 40s
south. Amplifying trough to the west pushes in through the day on
Monday. Strengthening southerly flow will allow highs to climb into
the upper 50s to low 60s, 3 to 5 degrees above normal. Start
bringing in precip chances by Monday afternoon but the bulk of the
precip will hold off until Monday night. The main focus for Monday
will be increasing winds due to strengthening 850mb jet.
By late afternoon, sustained winds across the lower elevations will
range from 10 to 15 mph with gusts from 15 to 20 mph. Winds in the
higher elevations will be sustained from 15 to 20 mph with gusts up
to 35 mph. Our highest peaks along the TN/NC line could gust up to
45 mph by late afternoon.
Monday night: Lows will be around 15 degrees above normal due to
strong southerly flow and cloud cover. Best chances for precip look
to occur between midnight and 7 am Tuesday. QPF amounts will
generally range from half an inch to one inch. Only expecting half
an inch up across NETN where downsloping winds will initially limit
precip. PW values are near max values for this date during the
overnight hours. The NAM and GFS both show a 60 to 70kt 850mb jet
moving across Monday night. It still looks like a high wind warning
will eventually be needed for our higher terrain along with an
advisory across the foothills for Monday night into Tuesday morning.
Across the high terrain, winds could gust over 60 mph which could
bring down quite a few trees. Will continue to watch this situation
closely. Still not sold on a mountain wave event. Wind direction is
not ideal and the inversion is lacking.
Tuesday: High winds diminish in the morning as the jet moves east.
There are big differences between the NAM and GFS regarding precip.
The nam wants to hang the front up across the mountains and allow it
to rain for most of the day, generally east of I-40. The GFS and
ECMWF are more aggressive with the front and push it east of us by
late Tuesday morning. Will split the difference with pops until
there is better model agreement. If the NAM verifies, precip through
the day Tuesday should generally be light to moderate. Highs will be
in the mid to upper 60s, around 10 degrees above normal.
At some point, we will see a break in the precip before the next
wave moves in. General consensus is that the next wave will move in
late Tuesday night into Wednesday morning. Another 1 to 3 inches of
rainfall is possible with this wave as it moves through as PW values
are again maxed out for this time of year. 850 mb jet isn`t nearly as
strong but the high terrain could still see gusts up to 30 mph.
Enough instability remains present to allow for thunder in grids
Tuesday night. Lows will remain mild and be in the low to mid 50s.
Precip pushes east by Wednesday afternoon before a third and final
wave moves in for Wednesday night into Thursday, where another inch
of rain is possible.
Precip ends on Thursday as a more zonal flow returns. Event total
precip from Monday night through Thursday will range from 2 to 4
inches for most areas, with locally higher amounts possible. Extreme
NETN and SWVA will see slightly lower amounts due to downsloping
early in the event. Quiet weather and more seasonable temps return
for the rest of the long term.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 30 63 43 62 / 0 0 0 20
Knoxville McGhee Tyson Airport, TN 28 60 38 62 / 0 0 0 20
Oak Ridge, TN 28 60 38 62 / 0 0 0 20
Tri Cities Airport, TN 25 58 31 58 / 0 0 0 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
MA/SR
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PST Sat Nov 26 2016
.SYNOPSIS...
Two quick moving weather systems will bring cooler weather,
showers and gusty winds this weekend. The best precipitation chances
will be late this afternoon into this evening and again Sunday
afternoon. Winds will be rather strong this weekend, especially
Sunday, with wind local gusts over 65 mph possible along the deserts
slopes of the mountains. There is a small chance of a few more
showers Monday evening in San Diego County. Cool weather will prevail
next week, with the potential for moderate to strong offshore flow
late in the week, though also with a small chance of precipitation
again Friday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
The trough is headed our way with precipitation moving into Orange
County already. The band of moderate to heavy precipitation will
move into the Inland Empire 2-3 PM and 3-4 PM in San Diego County.
With instability aloft due to 500 MB temps projected to be around -26
C and boundary layer CAPEs in the 500-800 J/kg range, there could be
thunder and gusty winds with the band. The 18-hour HRRR
precipitation totals have pretty consistently been 0.25 to 0.6 inches
west of the mountains and locally around one inch on west-facing
slopes in San Diego County, with overall rainfall greater in SD
County than points further north, and this is generally in line with
our previous forecasts. Snow levels will start out 6000-7000 ft
elevation this afternoon but fall to 5000-6000 ft by this evening,
mainly with the main band of precip, with highest snow levels in SD
County. Snowfall will generally be 1-4 inches late this
afternoon/tonight, including in showers, though limited moisture
above 700 MB will prevent snow from being too heavy. Winds will be
increasing behind the band as winds switch from south-southwest to
more of a westerly direction, and some of this will be synoptically
driven by the jet stream containing winds around 170-knots at 200 MB
and winds as high as about 55 knots at 700 MB. Expect peak gusts 60-
65 MPH tonight on the east-facing mountain slopes due to some
mountain wave enhancement of the wind, and even stronger Sunday with
local gusts around 70 MPH. Scattered showers will continue overnight
as quite a bit of moisture will remain below about 750 MB, except
possibly a brief decrease in moisture very early Sunday. The next
wave, with Gulf of Alaska origins, will move mostly by to the
northeast Sunday, but enough moisture will be available for at least
some precipitation, especially on the west facing mountain slopes.
Best over-the-water trajectory is over San Diego County where precip
amounts will likely be greatest. Low elevation precip amounts will be
0.1 to 0.3 inches with local mountains getting 0.5 to 0.8 inches. 1-3
inches of additional snowfall could occur. Despite the Gulf of Alaska
origins of this next wave, the snow levels will not change much.
Best precip will fall between about noon and 7 PM, with precip mostly
just over the San Diego County Mountains after that.
After that, partly cloudy conditions will prevail Monday, though a
weak wave sliding by to the northeast on the back side of the
Western US trough could bring a few showers to San Diego County
Monday night. Under the cool cyclonic flow aloft, it will remain
rather cool Monday, but a Pacific ridge will approach from the west
Tuesday and bring some warming to just below seasonal averages. Some
gusty northeast winds will occur below passes and canyons Tuesday as
a surface high builds into the Great Basin. Overall, the weak will
stay cool as the ridge weakens Wednesday and another trough moves
down from the north. This upper low is likely to cut off somewhere in
the southwest, with GFS solutions a little to our east over SW
Arizona/NW Sonora and ECMWF solutions much closer and with possible
precip. Even the GFS solution had small amounts of precip, so added
this to San Diego County around Friday. With tight gradients aloft
and a surface high forming in the Great Basin, there could be
moderate to strong offshore flow starting around Friday. Temperatures
will continue to be a little below seasonal norms through the end of
the week.
&&
.AVIATION...
262037Z...Through 2200 UTC...BKN-SCT clouds moving into the valleys,
passes and coastal slopes (causing mountain obscuration) while bases
and tops lift to 2000-2500 ft msl and 3500-5000 ft msl respectively.
2200-27/0600 UTC...OVC-BKN clouds in the 2500-16000 ft msl layer
with embedded SHRA and possible TSRA mainly over and W of the
mountains and in the High Deserts (with isol SHRA and locally lower
vis/cigs possible in the Lower Deserts), along with increasing W to
NW surface winds at the TAF sites. Expect areas of vis/cigs 2-5
sm/1500 ft agl due to SHRA with local vis/cigs AOB 1 sm/1000 ft agl
due to +SHRA/TSRA. CB tops to 20000 ft msl. Mountain obscuration of
coastal slopes continuing. Mod-stg uddfs/llws over and E or NE of
mountain ridges due to SW to W winds 15-25 kt with gusts 35-40 kt.
27/0600-1500 UTC...BKN clouds in the 2500-7000 ft msl layer with
embedded isol-sct -SHRA mainly over and west of the mountains, local
vis 3-5 sm, and mountain obscuration of coastal slopes. W winds over
mountain ridges/desert slopes/passes increasing to 20-35 kt with
gusts 40-60 kt, resulting in stg-svr uddfs/llws/rotors over and E of
the mtns. Lowered vis due to blowing dust/sand possible as well.
Otherwise, unrestricted vis and dry conditions expected for the
deserts.
&&
.MARINE...
Two short-wave troughs of low pressure will move through the region
late today through Sunday, bringing periods of showers. The cold
front that moves through this afternoon and evening could also
produce thunderstorms, with possible waterspouts, lightning, gusty
erratic winds, heavy rain and small hail. A Marine Weather Statement
has been posted.
These disturbances will also create strong west to northwest winds
over the coastal waters starting this evening, and strengthening
further Sunday morning. Winds of 15-20 kt with gusts to 30 kt are
likely for both the inner and outer waters. Also, strong
northwesterly winds outside our area will produce a fresh west-
northwest swell from 285 degrees which will combine with locally
generated wind waves to create steep and hazardous sea conditions,
with combined seas peaking around 10-13 feet. A Small Craft Advisory
goes into effect this evening and continues through late Sunday
night.
Winds will still be locally gusty in the outer waters on Monday, and
may be strong enough to warrant an extension of the Small Craft
Advisory.
&&
.BEACHES...
Steep, but short-period swells/wind waves from 290 degrees will
create elevated, sloppy surf with sets to 7 feet, and strong rip
currents along the beaches Sunday through early Monday. Isolated
thunderstorms are also possible along the beaches this afternoon
and early evening as a disturbance moves across the region.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning from 6 PM this evening to 10 PM PST Sunday for
Apple and Lucerne Valleys-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
Winter Weather Advisory from 6 PM this evening to 10 PM PST
Sunday for Riverside County Mountains-San Bernardino County
Mountains.
Wind Advisory from 8 AM to 6 PM PST Sunday for Orange County
Coastal Areas-Orange County Inland Areas-San Bernardino and
Riverside County Valleys-The Inland Empire-San Diego County
Coastal Areas-San Diego County Valleys-Santa Ana Mountains
and Foothills.
Wind Advisory from 6 PM this evening to 10 PM PST Sunday for
Coachella Valley.
PZ...Small Craft Advisory from 4 PM this afternoon to 4 AM PST Monday
for Coastal Waters from San Mateo Point to the Mexican
Border and out to 30 nm-Waters from San Mateo point to the
Mexican Border Extending 30 to 60 nm out including San
Clemente Island.
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PUBLIC...Maxwell
AVIATION/MARINE/BEACHES...Harrison