Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/27/16
Area Forecast Discussion
National Weather Service La Crosse WI
515 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 sheltered
areas 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 00Z TAFS through 00Z Sunday evening)
Issued at 515 PM CST Sat Nov 26 2016
VFR/SKC conditions expected through Sunday morning. Low clouds and
rain will move in by late afternoon (21-00z), and continue into the
overnight hours of Sunday. Expecting IFR/MVFR cigs and accompanying
low vsbys.
Of note - some models want to bring low clouds/low cigs into KRST
tonight - but they erroneously have a snow cover. Without that, the
threat of nocturnal br/cigs looks minimal.
Winds will stay light mostly southeast tonight...increasing later on
Sunday as the pressure gradient tightens ahead of the storm system.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DTJ/Boyne LONG TERM...DTJ AVIATION...Rieck
Area Forecast Discussion
National Weather Service Caribou ME
950 PM EST Sat Nov 26 2016
.SYNOPSIS...
Low pressure will track south of Nova Scotia tonight then up
through the Maritimes on Monday. High pressure will build over
the area Monday night then low pressure will begin to approach on
Tuesday.
&&
.NEAR TERM /THROUGH SUNDAY/...
915 PM Update: Latest sim radar imagery from the 01z HRRR and 00z
high resolution NAM takes the current new, Norlun like, precip
band moving nw from SE ME and Srn NB toward Cntrl ptns of the FA.
Both models indicate that unlike the last band of mdt to hvy sn
that affected NE Aroostook county this aftn, the impacts of this
new band may be more directed to areas further S and W, likely a
result of inverted sfc troffing becoming more defined alg the mid
ME coast and Penobscot vly. This should be the last stage of a
very tricky fcstg event, with the band xpctd to weaken ovr far NW
ME and just W of the Penobscot vly durg the morn hrs Sun. Precip
type will be all sn from Cntrl areas nwrd, with rn chgng to sn
late ovr interior Downeast areas as colder air at the sfc and alf
works swrd. Lctns receiving msly all sn with this new band could
receive an additional 1 to 2 inches, with stronger ptns of the
band producing lcly up to 3 inches.
Otherwise, fcst hrly temps and dwpts thru the late ngt and into
erly Sun morn were updated based on trends seen from mid eve obs.
No chgs were made to fcst ovrngt lows this update.
Orgnl Disc: An inverted trough extends from roughly Bar Harbor to
Clayton Lake. A band of moderate to occasionally heavy
precipitation has been lifting northward on the east side of this
trough. This band will remain nearly stationary into this evening
and then it will gradually shift westward as the trough
retrogrades toward western Maine. Temperatures will remain
somewhat steady early this evening, but cold air will begin to
spread into the state later tonight as winds turn to the north. As
such, northern Maine will continue to see snow through this
evening. Southern locations will gradually mix with and eventually
change over to snow, even as far as the coast. The snow may be
heavy at times, particularly through midnight. We are still
anticipating a swath of 4 to 8 inches over the north, with the
highest totals occurring over north central portions of Aroostook
County. Further south, the Central Highlands out to Houlton should
see 2 to 4 inches, while Bangor and Downeast will get less than an
inch. Locally higher totals are likely over higher terrain in the
North Woods and northern Aroostook County.
The aforementioned inverted trough will weaken early Sunday morning
as deepening low pressure lifting north into the Canadian Maritimes
takes over. This will allow the band to wane through the morning
hours; snowfall amounts daybreak through noon should be an inch or
less in most locations. Precipitation will continue to decrease in
coverage and intensity through the afternoon, ending from east to
west. Temperatures will peak into the mid 30s in the north to around
40 Downeast, but north winds and cloudy skies will make it feel
colder.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Low pressure will be exiting through the Maritimes Sunday night into
Monday as drier air pushes in from the west. Skies will remain
mostly cloudy Sunday night, but should then clear from southwest to
northeast on Monday as a thin ridge of high pressure builds in. The
high will crest over the region Monday night allowing skies to be
mostly clear and the air to cool into the teens north and 20s
Downeast. Our focus then turns to a large storm system approaching
from the west on Tuesday. The main low will be over the northern
plains, but a large occlusion out ahead of the low will bring
increasing clouds late Tuesday followed by a chance of snow north
and rain Downeast late Tuesday. The rain snow line may depend on the
location of a secondary triple point low which may begin to form in
the western Gulf of Maine late Tuesday or Tuesday night.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The extended models are in good general agreement at the start of
the period. A cold frontal system will be pushing into western
Maine at the start of the period. A Surface low over the northern
Great lakes region with a broad upper level low over Wisconsin and
Lake Superior. The frontal system wraps around the low into
southern Canada, then extends south across western Maine, then
south along the Atlantic coast. Wednesday morning the frontal
system will move through Maine, and higher pressure will briefly
build across Maine. A trough extending east from the low over the
northern Great Lakes into southern Maine will inter act with a
secondary low moving up the coast. By Wednesday evening the trough
will move to central Maine. The low moving up the coast will move
into Southwestern Gulf of Maine. Thursday evening the low in the
Gulf of Maine will deepen just south of Bar Harbor, an occluded
front will wrap around the low extending north into central Maine.
This system will bring rain to the coast and interior Downeast,
mixed precip to central Maine, and snow across the crown. Friday
morning the low will move east to the eastern coast of New
Brunswick. Wrap around pcpn will continue for northern and central
Maine. Friday evening the low will move east to Prince Edward
Island, Maine will remain in the wrap around pcpn. Saturday
morning the upper low will move into the region and a trough will
remain across the area. By the end of the period the trough will
finally clear the area and higher pressure will build in.
Loaded a blend to smooth out the minor differences in the models.
Loaded NAWAVE4 for seas in the coastal waters. Loaded windgust by
factor tool.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
NEAR TERM: LIFR will continue at all sites this evening and
overnight. Snow will fall, heavy at times, at FVE/CAR/PQI through
12z Sunday. The other sites will gradually transition from rain to
snow from north to south overnight. Northern terminals will remain
IFR through Sunday, but BGR and BHB will improve to MVFR 12z-16z
and remain so through the day.
SHORT TERM: MVFR conditions Sunday night should improve to VFR
conditions Downeast by Monday morning, then VFR across the entire
area by midday Monday. VFR conditions are expected Monday night
into Tuesday in high pressure, but could lower back to MVFR very
late on Tuesday as clouds increase.
&&
.MARINE...
NEAR TERM: The Small Craft Advisory has been extended until 4pm Sunday
for zone 50 (Eastport to Schoodic Pt) only as marginal SCA
conditions are expected to continue overnight. For zone 51, winds
have remained below 20 kt today as an trough remains in place there.
However, winds are expected to intensify late tonight into Sunday as
the trough shifts westward and north winds bring cold air advection.
Therefore, will a SCA is in effect for this area for 4 am Sunday to
4 pm Sunday. The inner waters will see gusts to around 20 kt late
tonight and Sunday but overall conditions will remain below SCA
levels.
SHORT TERM: Northwesterly winds may approach SCA in gusts to 25
kt over the offshore waters late Sunday night into Monday. Winds
should then diminish Monday night into Tuesday as high pressure
builds over.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 7 AM EST Sunday for MEZ001-002-
004>006.
MARINE...Small Craft Advisory until 4 PM EST Sunday for ANZ050.
Small Craft Advisory from 4 AM to 4 PM EST Sunday for ANZ051.
&&
$$
Near Term...VJN
Short Term...Bloomer
Long Term...Norton
Aviation...VJN/Bloomer
Marine...VJN/Bloomer
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
626 PM EST Sat Nov 26 2016
.AVIATION...
An uncertain, but low impact, aviation forecast is in store for
tonight particularly for the future of the VFR stratus. There are a
number of conflicting signals that needs to be sorted out. However,
a sharp trailing PV maximum is set to dig down the western flank of
longwave upper level low pressure this evening. Theta e ridging in
advance of this shortwave in addition to lingering cold midlevel
temperatures within the lower height anomaly should support
continuation of cloud throughout much of the night. Once this wave
ejects through and trailing subsidence backfills, particularly after
09Z...could see a concerted dissipation of the clouds. However, that
isn`t a clean call either as warm air advection ramping up late will
begin the process in developing a warm front over the region and an
increase in 900mb moisture. The one thing to watch for will be if
clouds clear out rapidly, as higher ambient near surface moisture
may contribute to fog formation. Will be watching 00Z guidance, but
may need to swing the forecast more in favor of reduced visibilities
and potential IFR cig heights through a good chunk of Sunday
morning. 4km NAM and HRRR are both bullish on this solution.
//DTW Threshold Probabilities...
* High for ceiling 5000 ft this evening...medium to high for late
tonight through Sunday morning.
&&
.PREV DISCUSSION...
Issued at 305 PM EST Sat Nov 26 2016
DISCUSSION...
Fairly quiet stretch of weather expected for the second half of the
weekend as the upper ridge now over the central CONUS slides into
the Great Lakes. Most challenging aspect of the forecast will be
cloud cover. Expect to see a reduction in clouds this evening as the
surface ridge axis passes over the area. This will weaken and back
flow across the lake and lower inversion heights, allowing clouds to
release from Lake Michigan. Trend can already been seen on satellite
imagery to our west. Latest high-res model data from the
HRRR/RAP/NAM then suggests that the lowering inversion heights will
serve to trap moisture arriving overnight behind a weak warm front.
This moisture is already apparent over Illinois and Missouri, with
surface observations reflecting the presence of low clouds and some
fog. There should be enough of a southerly gradient over Southeast
Michigan overnight to favor stratus over fog, as the ridge center
remains to our south. Cannot rule out a few patches of drizzle, but
will leave out of forecast for now as overall potential and any
impacts (non-freezing) look low. The clouds will keep temperatures
from falling too far from current readings overnight, with mins
expected to settle in the low or mid 30s. Moisture will linger into
tomorrow, with a slow lifting and thinning of cloud bases expected
through the day as mixing improves with the diurnal cycle. Will
stick with some of the cooler numbers in the mid 40s offered by
guidance for max temps.
Longwave trough will become established over much of U.S. Monday, as
energy now along the West Coast and the Gulf of Alaska consolidates.
A strong shortwave embedded within this trough will lift northeast
across Michigan Monday night and Tuesday, while we also become
positioned under strong upper diffluence in advance of strong
subtropical jet streak. Strong low-level jet will pull a good deal
of warm air and Gulf moisture (PW near 1 inch) into the Great Lakes
Monday into Monday night, working with large-scale forcing to
provide steady rain to the area. Drier air will rush into the area
as the low lifts into the northern Great Lakes on Tuesday, ending
chances for precipitation from south to north, but keeping a very
mild airmass in place.
The upper level large low centered over the Northern Plains will
continue to meander over the area for the remainder of the week. In
the meantime, the surface low will be in the process of lifting away
from the area. This will bring a chance for some showers along with
periods of drier weather through the week even as the region remains
in upper level troughing. Temperatures on both Tuesday and Wednesday
will be above normal as highs reach into the 50s before highs drop
back into the lower 40s for the beginning of December.
MARINE...
Marine conditions will remain favorable as high pressure drifts
across the Great Lakes tonight and then to the east Sunday.
Meanwhile, a large low pressure system will organize over the
central Plains states and then strengthen considerably over the
northern Plains and Midwest Monday through Tuesday. This system will
support a fresh southeast breeze from Lake Huron through western
Lake Erie Monday and likely reaching gales Monday night. The latest
model solutions indicate a deeper layer of instability over Lake
Huron ahead of the warm front/occlusion which could allow gales to
reach 40 knots before the occlusion moves north of the lake Tuesday.
Small craft advisories will likely be needed Monday, mainly for
waves on southern Lake Huron, ramping up to Gale watches now in
effect for all marine areas Monday night into Tuesday. Wind
conditions are projected to improve Tuesday night into Wednesday as
milder air and more stable conditions move over the region.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from Monday evening through Tuesday afternoon FOR
LHZ361>363-421-422-441>443-462>464.
Lake St Clair...Gale Watch from Monday evening through Tuesday morning FOR LCZ460.
Michigan waters of Lake Erie...Gale Watch from Monday evening through Tuesday morning FOR LEZ444.
&&
$$
AVIATION.....CB
DISCUSSION...HLO/SS
MARINE.......BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Sioux Falls SD
548 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 00Z TAFS through 00Z Sunday evening)
Issued at 540 PM CST Sat Nov 26 2016
With winds becoming light this evening, low clouds and areas of
fog will develop through the next few hours. Most favorable areas
will be east of the James River, with the lowest visibilities
possible in southwest Minnesota, northwest Iowa and the I-29
corridor. Expect only very minor improvements in visibility, while
low clouds will linger into Sunday. Showers will become likely
around midday throughout the region and will further reduce
visibility and lower ceilings.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...BT
LONG TERM...08
AVIATION...
Area Forecast Discussion
National Weather Service Gray ME
906 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/...
---905pm Update---
Precipitation over southern Maine is now primarily stationary. It
should remain that way over the next few hours and then just
diminish in place. Precipitation over the midcoast area is
expected to expand in areal coverage a bit and persist through
most of the night. Will update forecast package to handle these
features.
---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 /02Z SUNDAY 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
858 PM CST Sat Nov 26 2016
.UPDATE...
Issued at 858 PM CST Sat Nov 26 2016
Main concern overnight is the potential for an expanding area of
stratus/fog advancing northward through central Illinois after
midnight tonight. The HRRR and RAP guidance continue to agree on
advancing the low clouds and fog currently in southeastern
Missouri, northeast across central Illinois into northeastern IL.
The GFS is less pessimistic with clouds and fog, but have
significantly increased clouds and added fog across our entire
forecast area for tonight into tomorrow morning. The clouds could
work to keep lows slightly warmer, and we already were slightly
above guidance numbers so will hold the lows as previously
forecast, ranging from 33F in the east to 37F in the west. The
remainder of the forecast looks on track, with rain chances
increasing Sunday afternoon in our far western counties. Updated
forecast info is already available.
&&
.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 00Z TAFS through 00Z Sunday evening)
Issued at 616 PM CST Sat Nov 26 2016
Main concern tonight will be the increasing potential for IFR/LIFR
fog and/or stratus advancing north through central IL after 06z.
There is decent agreement in the RAP, HRRR and NAMNest of those
conditions between 06z (arriving at SPI) and 15z (dissipating/shifting
N of I-74 terminals). To trend in that direction, TEMPOs were
included from 10z-14z for IFR vis/cigs for now. Will monitor high
res updates and forecast soundings to see if prevailing LIFR
conditions need to be added later tonight.
Southerly winds will start out around 10-12kt early this evening,
then they should diminish to 6-8kt overnight. The steady
advection of the stratus/fog indicates we should maintain some
steady winds the entire night, and possibly as high as 10kt at
times.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Auten
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
612 PM CST Sat Nov 26 2016
.Updated for 00Z Aviation discussion...
Issued at 547 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 00Z TAFS through 00Z Sunday evening)
Issued at 547 PM CST Sat Nov 26 2016
IFR/LIFR conditions across central and western Minnesota with the
dense fog. Conditions will increase in coverage overnight. Areas
to the east should remain VFR/MVFR with some patchy fog. Looking
ahead, low clouds will lift northward Sunday afternoon, with rain
following for Sunday evening. Expect cloudy conditions to persist
for much of the upcoming week.
KMSP...
Cold see some patchy MVFR fog develop overnight. Otherwise expect
VFR conditions for the morning and early afternoon until stratus
moves up from the south around 21 to 22Z. Rain will follow a few
hours later, with IFR visbys/Cigs expected after sunset. Winds
will be southeast.
/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>044-047>050-
055>058-065.
&&
$$
SHORT TERM...MPG
LONG TERM...
AVIATION...JRB
Area Forecast Discussion
National Weather Service Phoenix AZ
846 PM MST Sat Nov 26 2016
.SYNOPSIS...
A cold Pacific storm system will move into the region Sunday and
Monday bringing wind, rain, and higher elevation snows throughout
much of southeast California and Arizona. While precipitation will
quickly clear the region by Tuesday, chilly weather will linger for
the remainder of next week. Another period of unsettled weather will
be possible by the end of next week as well.
&&
.DISCUSSION...
A thick canopy of mid and high clouds persists this evening across
much of Arizona ahead of a well-defined PVD moving eastward through
the Mojave Desert. Latest radar imagery indicates some weak returns
across portions of Pinal and southern Gila Counties. A sprinkle or
light shower is possible in these areas overnight, but the moisture
will generally help prime the lower levels of the atmosphere.
Meanwhile, breezy conditions have developed across portions of
southeastern California ahead of a frontal boundary. Gusts have
reached 30 to 35 in these areas, however latest runs of the HRRR
indicate that the winds will not pack as much of a punch further east
across the lower deserts of Arizona. The short-term forecast has been
updated to reflect these trends. Minor adjustments were also made to
the QPF and snow amounts for tomorrow night. Latest guidance suggests
around 0.4 inches of QPF across the highest elevations including Four
Peaks and Pinal Peak. A 12:1 snow ratio yields snow amounts up to 4
inches for these areas. Snow accumulations will remain confined to
elevations above 5500 feet.
&&
.PREVIOUS DISCUSSION...
Operational models as well as ensemble guidance has been very
consistent in their handling of the incoming pair of Pacific
shortwaves, both in timing/track of the systems and in their handling
of moisture/qpf. MOS POPs as well as ensemble POPS (such as SREF and
NAEFS) have been consistent as well and every thing continues to
point to the main precip event being a fast moving front bringing a
burst of showers/rainfall to mainly south central Arizona on Sunday
evening. Due to the high consistency of guidance and high forecaster
confidence, only very minor changes/tweaks have been made to the
forecast package on this shift.
Little precip is expected through Sunday afternoon however. We will
see high temperatures fall sharply Sunday, falling into the low to
mid 60s over much of the lower desert as the front rapidly sweeps
east across western and central AZ.
Biggest weather impact will come on Sunday evening as strong QG
forcing comes together along with the effects of the frontal
passage. We expect a band of showers to race east across south
central AZ Sunday evening bringing numerous showers of rain and high
elevation snow to the area. Rain totals will be limited due to the
fast moving nature of the front, with desert totals expected to be
below one quarter of an inch, and higher terrain values between one
quarter and one inch. Snow levels should fall to around 5000 feet by
Monday morning and snow amounts should be below 3 inches and
confined mainly to elevations above 5000 feet with just light
amounts or a dusting down to 4500 ft. Another impact will be strong
gusty west winds across the western deserts Sunday afternoon and
early evening; for the most part winds will remain a bit below wind
advisory levels but gusts of 30-40kt are possible for an hour or two
especially in favored areas of Imperial County as well as in Joshua
Tree NP and along the Lower Colorado River valley. Blowing dust is
certainly possible as well and continues to be advertised in our
grids.
Most of the precipitation should be over shortly after midnight on
Sunday night; the trof will be moving off quickly towards the east
and strong mid level Q-divergence bullseye overspreads the central
deserts in its wake leading to strong subsidence and clearing.
For Monday into Tuesday, behind the exiting second upper trof, we
fall under a cool, slightly cyclonic, northwest flow regime.
Embedded in this flow are a series of weak disturbances bringing
mostly channeled vorticity and weak UVV. Cool air aloft will also
aid in the formation of instability showers and overall we will
remain a bit unsettled over the higher terrain to the east of
Phoenix. Thus Monday into Monday night we will keep a slight chance
of rain and higher elevation snow showers north and east of Phoenix.
The snow level will range from 4500 to 5000 feet but any snow down
to those elevations will be very light, well below one inch. High
temperatures both days will stay well below seasonal normals with
the central deserts staying mostly in the lower 60s with cooler
outlying areas north/northeast of Phoenix in the upper 50s.
Primarily northwest flow aloft (though becoming zonal later in the
week), strong sfc high pressure over the Great Basin, and lingering
cold advection will keep temperatures hovering in a below normal
category through most of next week. Model evidence strongly
continues to point towards the first widespread killing freeze for
the Globe/Miami area Wednesday morning (essentially all trusted
model sources show below freezing temperatures). There is also
growing evidence that subfreezing temperatures will affect
sheltered, low elevation areas of northern Pinal County, and morning
lows easily supporting frost in the outer Phoenix suburbs.
Otherwise, forecast confidence is very good that afternoon highs
will only reach the middle to upper 60s at low elevation population
center during the midweek time frame.
Operational and ensemble members are coming into better agreement
regarding a positively tilted wave/cutoff feature descending into
the SW Conus/western Mexico during end of the week/next weekend.
Historically, model solutions that incorporate these type of
Southwest cutoff systems that stall or retrograde carry low
confidence; and would not be surprised to see numerous variations on
this theme in future model iterations. Ensemble member naturally
show quite a spread ranging from an open progressive wave rapidly
ejecting into the plains to a deep negative height anomaly
retrograding well SW of the Baja peninsula. However, it should be
noted the ensemble mean generally matches operational members who in
turn look fairly similar. All told, have highlighted some increased
precipitation chances beginning Friday understanding the
traditionally these type of situations generally produce some light
showers only to have the area overtaken by stronger high pressure
building southward from the Great Basin.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Thick high clouds overhead will continue through this evening with
some lowering of cloud bases down to 15-20K feet. Easterly winds
early this afternoon will shift briefly out of the south creating a
period of southerly cross-runway winds in a 10-15kt range before
veering to a W/SW component around 00Z. After midnight, a cold front
will race through the Phoenix metro with stronger westerly gusts
25-30kt occurring during an atypical time frame (though during a
period of low traffic volume). Winds to decrease but remain out of
through Sunday morning.
Another weather system will move in for later Sunday bringing
much lower CIGS, potentially down to 3-4K feet briefly Sunday
evening along with a good chance of a couple hour period of rain.
Southeast California/Southwest Arizona including KIPL and KBLH:
Strong westerly wind gusts late this afternoon and evening will be
the greatest aviation impact for SE California. Thick high clouds
will scatter out this evening leaving mostly clear skies through
Sunday morning. Wind gusts this evening will approach 30kts and
diminish somewhat after midnight but remain gusty at times.
Another weather system will move through later Sunday with
increasing winds and gusts again approaching 30kts for Sunday
afternoon. There is a chance of some isolated showers, but definitely
not enough to include in area TAFs.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Monday through Friday:
A strong but fast moving Pacific storm system will be exiting the
districts Monday leaving light valley rains and higher elevation
snows in its wake, along with much cooler temperatures. In fact,
many higher foothill locations and all high terrain areas should
receive a killing freeze Wednesday morning. With air temperatures
hovering slightly below normal, minimum afternoon humidity values
will generally fall into a 15 to 30 percent range following good
overnight recovery. Wind speeds will be somewhat strong and gusty
down the Colorado River valley Tuesday afternoon, but otherwise
fairly light for the remainder of the week. A period of more
unsettled wet weather may begin to encroach on the region late next
week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports of wind and dust may be needed in SE California
Sunday, while snow reports may be needed in Gila County Monday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...CB/Hernandez/MO
AVIATION...Kuhlman
FIRE WEATHER...MO
Area Forecast Discussion
National Weather Service Sacramento CA
425 PM PST Sat Nov 26 2016
.SYNOPSIS...
An incoming storm will bring rain to the valley and snow to the
Sierra tonight through Sunday afternoon. A second system moves
into NorCal late Sunday night into Monday with drier conditions on
Tuesday.
&&
.Discussion...
Model analysis and water vapor imagery indicated a high amplitude
trough of low pressure moving across California during the early
afternoon hours. Radar imagery indicated a north to southward
oriented area of rain and snow along the foothills of the Sierra.
Elsewhere across the forecast area, overcast conditions were
present with temperatures ranging from the upper 40s to lower 50s
in the Valley.
The NAM and HRRR model forecasts seem to be handling the current
radar trends the best with a band of rain against the Sierra with
a dry area over the valley for an hour or two, and then another
area of precipitation moving into northern California from the
coast. If the precipitation stays on track as expected, widespread
areas of 5 to 10 inches of snow in the Sierra will result by late
Sunday morning. A winter weather advisory is still in effect
through Sunday morning with slippery roadways and low visibility
in falling snow. Traveling could become difficult and chain
controls could become likely for the mountain passes, so traveling
is discouraged unless necessary.
Snow and rain will briefly end on Sunday before the next round of
precipitation moves into northern California Sunday night through
Monday morning. Additional snowfall between 1 and 2 inches is
expected for elevations higher than 3500 feet.
Once precipitation tapers off Monday morning, a period of dry
weather will last through Tuesday night. Temperatures across the
forecast area will remain near normal in the 50s for the
Valley/foothills and 30s/40s for higher elevations.
&&
.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
A shortwave trough is expected to move into the Pacific Northwest
by mid-week. Model guidance is coming into better agreement
regarding the details of this system, but the ECMWF is still
the fastest solution. This system might bring a chance of showers
for the northern portions of our CWA on Wednesday, but dynamics
do not look that impressive. GFS and ECMWF dig this low into the
Great Basin Thursday, with possible lingering Sierra showers under
cyclonic flow. Ridge aloft builds across the region late next
week. This should result in dry conditions and daytime highs
around 3-7 degrees above normal.
&&
.AVIATION...
MVFR/IFR conditions expected across TAF sites as a storm system moves
into interior Norcal. IFR ceilings/visibilities over Sierra
overnight as heavy snow showers move through the area.
Precipitation should persist across TAF sites generally through
12z-15z Sunday timeframe. Southerly winds to 15 knots in the
valley with gusts to 30 knots over higher Sierra locations.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 4 AM PST
SUNDAY FOR SHASTA LAKE AREA / NORTHERN SHASTA COUNTY...
Winter Weather Advisory until 10 AM PST Sunday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
Winter Weather Advisory until 10 AM PST Sunday for Burney Basin/
Eastern Shasta County-
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
303 AM CST Sun Nov 27 2016
.UPDATE...
Issued at 303 AM CST Sun Nov 27 2016
Increased coverage of showers and measurable rain in the forecast
through this morning. Increased the pops, given the consistency of
the HRRR and after coordinating with WFOs GLD/AMA. Starting to
look like a fast-moving band of showers will race across the CWA
this morning. Stratus will spread quickly NW through sunrise, as
seen with the falling ceilings at Pratt, along with areas of
drizzle.
&&
.SHORT TERM...(Tonight through Sunday Night)
Issued at 1230 AM CST Sun Nov 27 2016
Active weather expected across SW KS today, with the primary
concern being strong to damaging winds, both with and outside of
any convection.
Moisture advection is underway this morning, both in the lower and
upper levels, as subtropical moisture is tapped and what limited
gulf moisture there is streams north with the low level jet.
Stratus ceilings will overspread SW KS through sunrise, with areas
of drizzle likely. Elevated south winds should keep the boundary
layer mixed and prevent fog formation.
HRRR solutions generate showers and convection over NE New Mexico
by 6 AM, and then spreads this activity NE into SW KS this
morning. ECMWF also generates QPF signals during the 6am-noon
time frame as intense jet dynamics begin to interact with
moist/warm advection. For these reasons, began scattered pop
coverage for showers/isolated thunder/drizzle starting immediately
at 6 AM and continued them through noon.
Strong shortwave currently near Las Vegas and the Grand Canyon
early this morning will be near the Four Corners near sunrise.
This shortwave will race NE, with a pronounced negative tilt,
arriving at the CO/KS border around noon, and central Nebraska
around sunset this evening. Strong surface cyclogenesis will
result north of SW KS, accompanied by very strong SW winds this
afternoon. Sharp dryline will advance west to east quickly
after noon, in response to strong cyclogenesis to the north.
Dryline is expected to reach Dodge City roughly around 1 pm.
West of the dryline this afternoon, intense SW winds will develop,
with frequent gusts of 45-55 mph. Included areas of blowing dust
in the grids. GFS soundings for 3 pm in the dry sector show the
boundary layer mixing dry adiabatically to near 650 mb/9k ft,
where flow is forecasted to be about 60 mph. As such, wind gusts as
strong as 60 mph are certainly possible. Forecast soundings still
show 45 mph at about 500 feet this afternoon, so gusts that strong
are a certainty. Do not have enough confidence to hoist a high wind
warning, but it will be close. Strongest winds are expected 1-5 pm,
with winds quickly diminishing through sunset.
That said, SW/W winds will continue to gust over 30 mph well into
the evening hours.
East of the dryline this afternoon, scattered showers and
thunderstorms are expected, with coverage favoring the eastern and
NE zones. HRRR output and other CAMs show cellular convection
(perhaps low-topped supercells) over the NE CWA 2-4 pm, SE of the
deepening surface low. Clearly, moisture and instability will be
highly limited. That said, any convective element will enhance
momentum transfer to the surface and will increase the risk of
damaging winds (even if the thunderstorm itself is meager). Any
rain showers or virga shafts will possess the potential for wind
gusts over 60 mph. Per coordination with SPC, the 5% marginal wind
risk continues for the northern zones this afternoon.
Tonight...Clear with slowly diminishing W/SW winds as cyclone`s
dryslot invades SW KS. Much drier air would argue for stronger
radiational cooling tonight, but mixing winds and a downslope
component should low temperatures Monday morning generally in the
30s.
.LONG TERM...(Monday through Saturday)
Issued at 200 AM CST Sun Nov 27 2016
Another extended period of quiet and (unfortunately) dry weather
is coming to SW KS. Powerful 522dm closed low in the Dakotas on
Monday will only slowly meander eastward through the Great Lakes
through Thursday, keeping us in dry and cool, subsident NW flow.
No hope of any precipitation in this pattern, and the forecast is
dry. Temperatures will certainly feel like the season, restricted
mainly to the 40s in the afternoons, and well below freezing at
night. NW winds will increase each afternoon Tuesday and
Wednesday, adding to the chill.
A closed low diving south through Nevada on Thursday will sink all
the way to Baja California on Friday. 00z ECMWF buries this closed
low well into Mexico through next weekend, keeping any rain/snow
well SW of SW KS. Operational GFS/superblend is very similar, but
is a bit more optimistic, with some light snow entering SW KS
early Saturday, as the closed low`s deformation clips the region.
Even the GFS storm track would keep the vast majority of
meaningful (and needed) precipitation south of us in Texas next
weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1100 PM CST Sat Nov 26 2016
Several impacts to aviation during this TAF cycle. LLWS will
continue for the next several hours, as LLJ and SW 850 mb winds
increase to near 50 kts. Moisture advection will push widespread
IFR/MVFR cigs in stratus across the terminals after about 09z Sun.
The lowest cigs are expected at DDC/P28/PTT where IFR is most
likely. Low stratus will also impact GCK/LBL for several hours
Sunday morning before dryline arrival by 18z Sun. MVFR stratus may
persist as long as 19-20z Sun at HYS. Areas of -DZ were included
in the TAFs, but strong south winds should keep BR/FG and any vis
restrictions limited.
Primary impact to aviation Sunday afternoon will be intense SW
winds, in response to strong cyclogenesis north of SW KS. After
18z Sun and behind the dryline, SW wind gusts of 40-45 kts will be
common, affecting GCK/LBL/DDC. Areas of BD behind the dryline may
reduce vis at times. Slightly less SW wind (25-35 kts) from HYS to
P28. An isolated SHRA/TSRA is possible near HYS after 20z Sun. Any
convection near HYS may produce damaging winds, but confidence on
direct impacts to the HYS terminal is low. After 00z Mon, SW winds
will diminish somewhat but remain quite elevated gusting near
30 kts. VFR/SKC expected Sunday evening.
&&
.FIRE WEATHER...
Issued at 200 AM CST Sun Nov 27 2016
Will maintain red flag warning as inherited for this afternoon.
After a period of low clouds, drizzle and a few rain showers this
morning, rapid drying and very strong SW winds are expected behind
a dryline this afternoon. Relative humidity will fall to 10-20%
from 1-5 pm, as SW winds gust near 50 mph. With moderate drought
and widespread cured/dry fuels, the risk of wildfire spread,
should an ignition occur, warrants the red flag warning. The most
critical time period of strong winds and low RH behind the dryline
will be from 1-5 pm, before W/SW winds begin relaxing around
sunset, and relative humidities slowly recover. Fire managers and
crews in the fields should monitor for any ignitions this
afternoon; extreme fire behavior is possible.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 70 35 59 29 / 50 0 0 0
GCK 66 32 57 27 / 50 0 0 0
EHA 63 33 55 28 / 60 0 0 0
LBL 68 32 58 27 / 60 0 0 0
HYS 65 36 57 30 / 40 10 0 0
P28 63 40 62 33 / 40 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM CST /noon MST/ this afternoon to 7 PM
CST /6 PM MST/ this evening for KSZ043>045-061>064-074>078-
084>088.
&&
$$
UPDATE...Turner
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Turner
FIRE WEATHER...Turner
Area Forecast Discussion
National Weather Service Wilmington NC
357 AM EST Sun Nov 27 2016
.SYNOPSIS...
High pressure will move in from the west during today with it`s
center moving overhead tonight and off the Carolina coasts and
offshore on Monday. A warm front will push across the area
early Tue followed by an influx of warm temperatures with highs
both Tue and Wed well into the 70s. Showers and isolated
thunderstorms will occur along and ahead of a cold front by
late Wednesday thru early Thursday. After it`s passage, look
for clearing skies late Thursday thru the upcoming weekend as
high pressure accompanied with near normal temperatures affects
the area.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Sunday...A crisp start early this morning will
undergo 25- 30 degree temperature rises today as continental
high pressure moves into the area, offering near cloudless skies
and low humidity levels. The air-mass remains resident into
Monday so another chilly overnight period tonight can be counted
on. High clouds from an upstream wave will stretch into the
region late tonight, which may impede ideal longwave heat escape
into the pre-dawn hours. Minimums daybreak Monday 33-37 inland,
around 40 by the coast.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Primary headliner this period `increasing
rain chances` into Tuesday as short-wave energy ahead of a cold
front picks up a moisture tap. Monday expect mainly clouds as the
dry continental air mass holds on, but erodes into late Monday. A
1/4 inch or less of rainfall expected Tuesday. The strong warm
air advection will bring soaring temperatures well above normal
Tuesday into the upper 70s mixed with the showers, and balmy,
gusty wind of 20 to 30 mph in the afternoon Tuesday.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 330 AM Sunday...Wednesday will be the warmest day of this
period with widespread 70s for highs, possibly a few 80 degree
marks depending on the extent of the cloudiness and possible
pcpn. Wed starts out with an amplified pattern aloft with
ridging and its axis having moved off the East Coast of the U.S.
while a cutoff low over the north central U.S.takes shape. The
tapping of the Gulf of Mexico and the Atlantic will provide the
necessary moisture for clouds and pcpn. The upper cutoff low is
progged by models to push east to and across the Great Lakes by
midday Thu. A decent vort or midlevel s/w trof will rotate
around the cutoff low will bottom out around Louisiana early
Wed then lift NE to the Mid-atlantic and NE states by late Thu
morning. The direct dynamics from this vort stays west and north
of the ILM CWA, however, 300mb jetstream dynamics indicate the
SE U.S. and the mid-Atlantic area will be on the RR Quadrant of
this upper jet, meaning decent UVVS will occur. And this so
happens to As of 3 AM Sunday...Primary headliner this period
`increasing rain chances` into Tuesday as short-wave energy
ahead of a cold front picks up a moisture tap. Monday expect
mainly clouds as the dry continental air mass holds on, but
erodes into late Monday. A 1/4 inch or less of rainfall expected
Tuesday. The strong warm air advection will bring soaring
temperatures well above normal Tuesday into the upper 70s mixed
with the showers, and balmy, gusty wind of 20 to 30 mph in the
afternoon Tuesday. take place Wed night thru early Thu just
prior to the sfc cold frontal passage. Thus will have frontal
dynamics, jetstream dynamics and a progged SSW to SW 40 to 50 kt
low level jet at less than 1k feet via GFS Bufr soundings. All
of this points to a decent shot of pcpn Wed aftn thru Thu
morning. PCPN type will primarily be showers with isolated
thunderstorms. The convection will depend on the availability of
instability. In other words, the convection threat will come
from high shear and low Cape scenario. Have continued to
illustrate isolated convection during that time frame until the
CFP early Thu. The isolated severe threat still looks too low to
mention in the forecasts at this time.
After the CFP, look for slowly improving conditions later Thu
thru Fri. The CAA surge and clearing skies will lag well behind
the cold front, likely occurring Thu night and Fri. Thus, Thu
max temps could again reach 70+ degrees with partly to variably
cloudy skies. For Fri and Sat, a return back to normal climo
temperatures with around 60 for highs and upper 30s to around 40
for lows under mainly clear skies.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
As of 06Z...VFR conditions expected thruout the 24 hr TAF
issuance period.
Amplifying mid-level ridging to affect the forecast area this
period. The north to south mid-level ridge axis will remain
just west of the FA this period. The center of high pressure
will migrate eastward and overspread the eastern Carolinas
today through tonight. N to NNE Winds will remain active, less
than 10 kt, this morning thru this afternoon. The sfc based
inversion will develop at or just after sunset late this
afternoon with winds decoupling, becoming calm for this evening.
No clouds other than possible cirrus late this period as the
mid-level ridge axis moves closer.
Extended outlook...VFR expected late Sun night thru Mon night.
Potential for MVFR conditions from scattered showers Tue.
Possible MVFR and IFR conditions from numerous showers with
isolated thunderstorms by late Wed thru Thu morning.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Sunday...ENE waves 3-5 feet every 6-7 seconds
highest offshore and gusty N winds early this morning will
prevail at least through the morning. The gusts will ease this
afternoon as the surface high migrates a bit closer to the
coast. Sea heights accordingly will ease gradually by a foot or
1.5 ft later today, thus an improving marine trend on tap
through the near term period. Winds to lighten and veer onshore
into early Monday as the high center nears the Outer Banks. No
TSTMS or VSBY restrictions expected this period.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Chief concern this period is worsening
marine conditions into Tuesday as southerly winds increase ahead
of an upstream low pressure system. Small Craft Advisory
Conditions appear likely sometime on Tuesday as seas build to
6-8 feet every 8 seconds by Tuesday evening offshore. Marine
showers can be expected Tuesday and gusty S winds of at least 25
KT. A few TSTMS are possible offshore tuesday.
LONG TERM /WEDNESDAY THROUGH THURSDAY/...
As of 330 AM Sunday...Looking at SCA conditions likely for both
days. Wed will be the 2nd day of strong SSE to SSW flow at 15 to
25 kt. Depending on local SSTS, winds of 30-40 kt just off the
deck, could mix down to the ocean sfc as Gale force gusts Wed
aftn thru early Thu morning. The chance for convection will
occur ahead of the cold front from Wed aftn thru Thu morning,
the latter time is when the cold front pushes offshore. The sfc
pg loosens during Thu allowing wind speeds to diminish-some.
Significant seas will become fully risen under the strong SSE-
SSW flow during Wed, with 5 to 8 ft likely, up to 9 ft outer
waters especially off Cape Fear where the onshore flow will help
push in higher SSTs across a portion of the ILM coastal waters
enabling those stronger wind gusts to possibly miduringx down
to the sfc. Periods will run from 7 to 8 seconds, ie. a pseudo
or fresh swell. With an offshore wind direction during Thu, seas
will only slowly subside to 3 to 6 ft by the end of the day,
Thu.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
NEAR TERM...MJC
SHORT TERM...MJC
LONG TERM...DCH
AVIATION...DCH
Area Forecast Discussion
National Weather Service Lincoln IL
335 AM CST Sun Nov 27 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 334 AM CST Sun Nov 27 2016
A storm system, that is progged to become quite strong, is beginning
to develop over the Plains. This system will begin to impact central
and southeast Illinois later today, with its impacts being felt for
the next couple of days.
Southerly low-level winds have developed across the region behind a
departing ridge of high pressure, and ahead of the developing
system. Low-level moisture return ahead of the system has developed
an area of stratus/fog from Arkansas into extreme southwest
Illinois. Forecast guidance is all over the place with respect to
how this stratus will evolve today. Some of the higher resolution
guidance has the stratus quickly covering the entire forecast area
with clouds this morning, while much of the other guidance has
clouds only increasing gradually today as the main storm system
approaches and clouds thicken from the top down. Given the strong
low-inversion that is currently in place, and will only be
strengthened by strong WAA aloft, have leaned sky forecast toward
the more pessimistic high-res guidance. However, have slowed the
onset of the clouds based on satellite loops/trends. Have nudged the
forecast highs a little cooler today, mainly a few degrees either
side of 50, with the earlier expected arrival of the thicker cloud
cover.
Most of the day should end up dry across the forecast area, but it
will quickly trend rainy by tonight. A vigorous short wave over the
southwest U.S. will eject northeast into the Midwest by tonight. A
period of enhanced isentropic ascent will spread from west to east
across the forecast area tonight with the passage of this wave. This
forcing will result in widespread showers across the region. A mild
night is on tap given the strengthening southerly winds with the
approaching storm system. Expect overnight lows in the 40s to only
be around 5 degrees below the daytime highs.
&&
.LONG TERM...(Monday through Saturday)
ISSUED AT 334 AM CST Sun Nov 27 2016
A vigorous upper level trof over the Pacific States, will move east
into the Great Plains Monday with a cutoff low over the eastern
Dakotas border by sunset Monday. Surface low pressure ejects ne from
CO into this area too, and IL to have strong warm air advection and
moisture advection ahead of this storm system through Monday. Still
appears to be a lull in the rain showers over nw CWA Monday morning
while showers likely continue over southeast IL. Along with the low
clouds and scattered showers, may see some fog and drizzle by Monday
morning over areas from I-74 northeast. But will also see fairly
strong southerly winds on Monday with gusts of 25-35 mph.
Will see showers expand during Monday afternoon/evening from
southeast IL back up into central and east central IL with
thunderstorms possible Monday afternoon and Monday evening. Showers
will quickly end from west to east behind a prefrontal trof
overnight Monday night. Rainfall amounts by overnight Monday night
will range from 0.75 inches by Galesburg, to about 1 inch along I-55
and 1.50 inches over southeast IL from I-70 southeast. These heavier
rainfall amounts aided by 45-60 kt 850 mb ssw jet and precipitable
water values of 0.75-1.25 inches especially east of the IL river.
Highs Monday in the low to mid 50s. Lows Monday night in the low to
mid 40s, mildest in eastern IL. SPC keeps marginal risk of severe
storms Monday afternoon/evening south of IL over far southern MO
into AR with a slight risk of severe storms over the southern MS
river valley, with an enhanced risk of severe storms over nw half
of LA.
Tuesday looks like the mildest day of the week with highs in the
upper 50s/lower 60s with return of mostly sunny skies and breezy ssw
winds. Large low pressure system moves into west central MN by
sunset Tue while a weakening cold front moves east over IL Tue night
and appears to pass through dry.
Latest forecast model ensembles continue to show a large upper level
low slowly weakening from central MN Wed and into the northern
GreatLakes Wed night. Meanwhile another surface wave develops and
lifts northeast along a frontal boundary southeast of the Ohio river
near mid TN on Wed. Most of the forecast models continue to keep qpf
southeast of our CWA on Wed with just the ECMWF model showing light
qpf in far southeast IL at 12Z/Wed. Will continue a dry forecast Wed
as low clouds increase especially Wed afternoon, along with cooler
high temperatures Wed in the mid to upper 40s over central IL and
lower 50s in southeast IL.
Large low pressure system moves into the eastern Canadian/St
Lawrence valley late this week while another cutoff upper level low
emerges over the desert sw by Friday. IL is in between these two
features and in a dry confluent upper level flow. Some light snow
showers will impact the great lakes and latest forecast models
keeps these north of CWA, though have increased cloud cover during
2nd half of week especially north of I-70. Temps cool closer to
normal for early December with highs of 39-45F from Thu thru
Sunday and lows in the upper 20s/lower 30s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1146 PM CST Sat Nov 26 2016
Main concern tonight will be the potential for IFR/LIFR fog
and/or stratus advancing north through central IL after 09z. The
HRRR, RAP and NAMNest have been slowing down the arrival of the
clouds/fog with each run this evening. Satellite images are even
slower than the high resolution models, so there may be even more
delay of those conditions. Have enough confidence that we should
see some fog and low clouds, have continued with TEMPOs from 11z-
14z for LIFR vis/IFR cigs. Will be monitoring satellite trends, high
res model updates and forecast soundings to see if prevailing LIFR
conditions need to be adjusted later tonight. Models indicate fog
may linger until 16z-17z for the northern terminals, before
conditions improve to VFR.
Rain chances increase later Sunday afternoon for PIA/SPI, as the
next system approaches from the Plains. Forcing for precip
maximizes west of I-55 Sunday evening, so have prevailing rain and
MVFR conditions developing from west to east Sunday eve.
South-southwest winds look to remain steady at 9-13kt the rest of
the night. Winds will increase more dramatically Sunday evening
with the onset of rains, with S-SE winds at 13-15G26kt.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Bak
LONG TERM...07
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
257 AM CST Sun Nov 27 2016
.SHORT TERM...
257 AM CST
Through tonight...
The million dollar question on which today`s entire forecast
hinges is what will the stratus do. GOES rapid scan requested this
morning is showing the band of IFR stratus over eastern MO/western
IL making steady progress northeastward, with recent imagery also
showing some expansion in the areal coverage. MOS really not very
bullish with CIGS today, but the HRRR has been depicting this area
developing and advecting northeast into and across our CWA this
morning. Have trended the grids/forecast in that direction today,
shaving a few degrees off high temps and expanding the overcast
skies northeast to encompass most of the area by early afternoon.
This is far from a sure thing and anywhere that doesn`t get socked
in with stratus will likely see temps several degrees warmer than
current forecast. Probably not going to be much time this
afternoon for stratus to erode before extensive mid-high level
cloudiness overspreads the area in advance of first wave of rain
with huge deep low over the northern/central plains.
Band of rain, some of it probably falling at a good clip, will
spread across the area this evening. Still looks like 1/3" to
locally 3/4" of rain will fall tonight with this band, the back
edge of which should clear our eastern CWA before sunrise Monday
morning.
Izzi
&&
.LONG TERM...
257 AM CST
Monday through Saturday...
Monday looks to be dreary, breezy, and damp. Pronounced mid-level
drying in the wake of the first wave should result in little if
any meaningful precipitation through much of the day. Saturated
low levels, modest ascent, and collision and coalescence within
the stratus deck should support drizzle and fog. Fog could
actually grow potentially dense in the afternoon as dewpoints
creep up and temps remain locked close to 50.
Dense fog chances will be lesser across about the SE half to
third of the CWA Monday afternoon where another wave pivoting
around the big cut off low will result in an another period of
steady, healthy rainfall late Monday afternoon through Monday
evening. Showers should increase in coverage area wide Monday
evening as yet another spoke of vortcity pinwheels around the
low.
Both of these waves should clear the area prior to dawn Tuesday
and guidance is in good agreement in really substantial drying of
the entire column with forecast soundings strongly suggesting
skies becoming mostly sunny. The sunny skies within the windy,
warm sector of this cyclone should allow temperatures to respond
quite nicely. Local 925mb temp climatology suggests that we could
threaten 60F for highs Tuesday, with at least mid-upper 50s
looking like a lock if lingering cloud cover isn`t an issue.
Colder air mass will begin filtering into the area in the wake of
a cold front Tuesday night. Still looks like little fan fare with
the front, but a gradually cooler air mass will spill into the
area Wednesday. At some point Wednesday, would anticipate CAA
stratus to rotate into the area and begin what looks to be a
potentially long period of cloudy skies.
Deep cyclonic flow with moisture trapped beneath frontal inversion
should lead to day of day of cloudy skies and small diurnal temp
swings starting Wed night and continuing into next weekend. Will
need to watch for any subtle shortwave that could pivot around
this cut off low, as any one of them could produce some light snow
showers, though temps at this point look like they`d be too warm
for any accumulation. Kept the forecast dry for now, but something
to keep an eye on in coming days.
Izzi
&&
.AVIATION...
For the 06Z TAFs...
Changes are expected over the next 30 hours. First, have low
confidence in fog development tonight. Will feature MVFR vsby on
at RFD and DPA overnight.
An area of stratus currently over Missouri will continue to
spread north. Have medium confidence in the stratus reaching the
terminals this morning, but low confidence in the cig heights. IFR
stratus is psbl, but cigs may lift to MVFR by the time the stratus
arrives. Many guidance members suggest vsby will drop this morning
as the stratus moves in. Have very low confidence in those
solutions, so did not put lower vsbys in the TAFs at this time.
South winds are once again expected today with cigs bcmg VFR this
aftn.
South winds increase in speed and begin gusting to arnd 25 kt
tonight ahead of the next system. Rain showers shift west to east
across the terminals this evening. Cigs drop back to IFR by early
Monday morning, and rain will likely drop vsbys. Put MVFR vsby in
the TAF, but only have medium-low confidence.
JEE
&&
.MARINE...
209 AM CST
Headlines...Upgraded the gale watch to a warning for the open waters
and IL nearshore waters. Timing remains the same, this evening into
Monday night. Confidence is lower in gales occurring over the IN
nearshore waters, so left those under a Gale watch. A few gales may
occur, but not sure if they will be frequent enough to warrant a
gale headline. Also pushed back the start time of the gale watch for
the IN NSH waters to early Monday morning.
High pressure over the Ohio valley continues east, and the next low
develops over the plains this evening. The low deepens rapidly as
it reaches the Dakotas Monday. As such, south to southeast winds
increase to gales tonight. The low weakens slightly as it shifts
over Minnesota Tuesday morning, and its cold front swings over the
lake early Tuesday morning. Winds become southwest at 30 kt behind
the front, and there could be a couple gale force gusts to 35 kt
over the northern half of the lake. The low continues to weaken and
slowly shift east across the Great Lakes through late this week.
Winds will be southwest to west, and then become northwest Friday
behind the low.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ777-LMZ779...9 PM Sunday
TO 3 AM Tuesday.
Gale Watch...LMZ743-LMZ744-LMZ745...3 AM Monday TO 3 AM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Miami FL
423 AM EST Sun Nov 27 2016
.DISCUSSION...
At 400 am, doppler radar continued to show scattered showers,
with isolated thunderstorms, slowly dropping southward along
portions the Atlantic coastal waters. The latest HRRR and WRF
model runs prog this activity to skim the coastline, so a slight
chance of showers for the east coast metro region appears
warranted. The surface analysis this morning indicated a weak
front draped from east to west across the CWA. As this front
pushes south today, the overall flow pattern will begin to shift
to the northeast, ushering in slightly drier and cooler air.
Maximum temperatures may only top out in the upper 70s along the
east coast, to around 80 degrees inland.
On Monday, as high pressure builds to the north of region, winds
will continue to shift to the east/southeast and become breezy at
times. Maximum temperatures will remain similar to todays with
upper 70s along the east coast and near 80 degrees inland.
Lingering isolated light showers will be possible over the
Atlantic waters Monday night, but generally dry over the land. By
mid week, a warming trend will develop, as pressure heights aloft
increase. Maximum temperatures Wednesday and Thursday will range
from the low to mid 80s across the entire region, around 5 degrees
warmer than normal for this time of year.
Thursday into Friday morning, both the GFS and ECMWF push yet
another weak cold front southwards towards southern Florida. Ahead
of this feature, moisture and instability appear sufficient enough
to include a slight chance of scattered showers over our region.
&&
.MARINE...
A weak front dropping southward over the Atlantic waters this
morning will continue the threat of scattered showers, with a
slight chance of thunderstorms. Winds will be shifting to the
northeast later today, then easterly and breezy by Monday. Small
craft advisories are in effect from this evening through Monday
evening for gusty east winds 15-25 kt and seas 5-8 feet
developing along the the Gulf Stream.
&&
.AVIATION...
A cold front is currently over the lake region, slowly progressing
southward. This boundary is helping to cause showers and a few
thunderstorms over the Atlantic waters. The current forecast keeps
this activity mainly offshore, possibly affecting the coastal
areas through the night and into tomorrow. Even so, the forecast
is for VFR conditions at all TAF sites through the TAF period.
Even though there is no weather in the TAFs, some of the Atlantic
coastal area sites may experience an isolated shower through
Sunday night.
&&
.BEACH FORECAST...
There will be a moderate rip current risk today along the east
coast beaches. This will likely transition to a high risk
beginning Monday, due to increasing onshore flow.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 79 71 81 73 / 20 10 10 20
Fort Lauderdale 80 71 80 73 / 20 10 10 20
Miami 80 69 81 72 / 20 10 10 10
Naples 81 64 84 67 / 10 10 10 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 1 AM to 1 PM EST Monday for AMZ651-671.
Small Craft Advisory from 7 PM this evening to 7 PM EST Monday
for AMZ650-670.
GM...None.
&&
DISCUSSION...27/JT
MARINE...27/JT
AVIATION...13
BEACH FORECAST...27/JT
Area Forecast Discussion
National Weather Service Phoenix AZ
943 PM MST Sat Nov 26 2016
.UPDATE...Updated Aviation discussion.
&&
.SYNOPSIS...
A cold Pacific storm system will move into the region Sunday and
Monday bringing wind, rain, and higher elevation snows throughout
much of southeast California and Arizona. While precipitation will
quickly clear the region by Tuesday, chilly weather will linger for
the remainder of next week. Another period of unsettled weather will
be possible by the end of next week as well.
&&
.DISCUSSION...
A thick canopy of mid and high clouds persists this evening across
much of Arizona ahead of a well-defined PVD moving eastward through
the Mojave Desert. Latest radar imagery indicates some weak returns
across portions of Pinal and southern Gila Counties. A sprinkle or
light shower is possible in these areas overnight, but the moisture
will generally help prime the lower levels of the atmosphere.
Meanwhile, breezy conditions have developed across portions of
southeastern California ahead of a frontal boundary. Gusts have
reached 30 to 35 in these areas, however latest runs of the HRRR
indicate that the winds will not pack as much of a punch further east
across the lower deserts of Arizona. The short-term forecast has been
updated to reflect these trends. Minor adjustments were also made to
the QPF and snow amounts for tomorrow night. Latest guidance suggests
around 0.4 inches of QPF across the highest elevations including Four
Peaks and Pinal Peak. A 12:1 snow ratio yields snow amounts up to 4
inches for these areas. Snow accumulations will remain confined to
elevations above 5500 feet.
&&
.PREVIOUS DISCUSSION...
Operational models as well as ensemble guidance has been very
consistent in their handling of the incoming pair of Pacific
shortwaves, both in timing/track of the systems and in their handling
of moisture/qpf. MOS POPs as well as ensemble POPS (such as SREF and
NAEFS) have been consistent as well and every thing continues to
point to the main precip event being a fast moving front bringing a
burst of showers/rainfall to mainly south central Arizona on Sunday
evening. Due to the high consistency of guidance and high forecaster
confidence, only very minor changes/tweaks have been made to the
forecast package on this shift.
Little precip is expected through Sunday afternoon however. We will
see high temperatures fall sharply Sunday, falling into the low to
mid 60s over much of the lower desert as the front rapidly sweeps
east across western and central AZ.
Biggest weather impact will come on Sunday evening as strong QG
forcing comes together along with the effects of the frontal
passage. We expect a band of showers to race east across south
central AZ Sunday evening bringing numerous showers of rain and high
elevation snow to the area. Rain totals will be limited due to the
fast moving nature of the front, with desert totals expected to be
below one quarter of an inch, and higher terrain values between one
quarter and one inch. Snow levels should fall to around 5000 feet by
Monday morning and snow amounts should be below 3 inches and
confined mainly to elevations above 5000 feet with just light
amounts or a dusting down to 4500 ft. Another impact will be strong
gusty west winds across the western deserts Sunday afternoon and
early evening; for the most part winds will remain a bit below wind
advisory levels but gusts of 30-40kt are possible for an hour or two
especially in favored areas of Imperial County as well as in Joshua
Tree NP and along the Lower Colorado River valley. Blowing dust is
certainly possible as well and continues to be advertised in our
grids.
Most of the precipitation should be over shortly after midnight on
Sunday night; the trof will be moving off quickly towards the east
and strong mid level Q-divergence bullseye overspreads the central
deserts in its wake leading to strong subsidence and clearing.
For Monday into Tuesday, behind the exiting second upper trof, we
fall under a cool, slightly cyclonic, northwest flow regime.
Embedded in this flow are a series of weak disturbances bringing
mostly channeled vorticity and weak UVV. Cool air aloft will also
aid in the formation of instability showers and overall we will
remain a bit unsettled over the higher terrain to the east of
Phoenix. Thus Monday into Monday night we will keep a slight chance
of rain and higher elevation snow showers north and east of Phoenix.
The snow level will range from 4500 to 5000 feet but any snow down
to those elevations will be very light, well below one inch. High
temperatures both days will stay well below seasonal normals with
the central deserts staying mostly in the lower 60s with cooler
outlying areas north/northeast of Phoenix in the upper 50s.
Primarily northwest flow aloft (though becoming zonal later in the
week), strong sfc high pressure over the Great Basin, and lingering
cold advection will keep temperatures hovering in a below normal
category through most of next week. Model evidence strongly
continues to point towards the first widespread killing freeze for
the Globe/Miami area Wednesday morning (essentially all trusted
model sources show below freezing temperatures). There is also
growing evidence that subfreezing temperatures will affect
sheltered, low elevation areas of northern Pinal County, and morning
lows easily supporting frost in the outer Phoenix suburbs.
Otherwise, forecast confidence is very good that afternoon highs
will only reach the middle to upper 60s at low elevation population
center during the midweek time frame.
Operational and ensemble members are coming into better agreement
regarding a positively tilted wave/cutoff feature descending into
the SW Conus/western Mexico during end of the week/next weekend.
Historically, model solutions that incorporate these type of
Southwest cutoff systems that stall or retrograde carry low
confidence; and would not be surprised to see numerous variations on
this theme in future model iterations. Ensemble member naturally
show quite a spread ranging from an open progressive wave rapidly
ejecting into the plains to a deep negative height anomaly
retrograding well SW of the Baja peninsula. However, it should be
noted the ensemble mean generally matches operational members who in
turn look fairly similar. All told, have highlighted some increased
precipitation chances beginning Friday understanding the
traditionally these type of situations generally produce some light
showers only to have the area overtaken by stronger high pressure
building southward from the Great Basin.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Latest guidance suggests westerly winds will develop around 06z with
gusts around 20 kt. Winds will then subside somewhat during the
morning before breezy conditions return during the afternoon ahead
of the next low pressure system. Ceilings are also expected to
develop with bases around 5k ft during the late afternoon. However,
there is the potential for even lower ceilings, particularly between
01z and 05z Monday when a line of showers moves through the Phoenix
area.
Southeast California/Southwest Arizona including KIPL and KBLH:
Wind gusts will be the main aviation weather concern. Westerly and
southwesterly gusts to 25 kt are expected early this evening before
abating somewhat between and 10z and 13z. Windy conditions will then
redevelop Sunday afternoon with gusts to 30 kt likely at KIPL/KBLH.
Conditions will improve Sunday evening as the gusts again subside
but remain sustained at 12 kt around 03z Monday.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Monday through Friday:
A strong but fast moving Pacific storm system will be exiting the
districts Monday leaving light valley rains and higher elevation
snows in its wake, along with much cooler temperatures. In fact,
many higher foothill locations and all high terrain areas should
receive a killing freeze Wednesday morning. With air temperatures
hovering slightly below normal, minimum afternoon humidity values
will generally fall into a 15 to 30 percent range following good
overnight recovery. Wind speeds will be somewhat strong and gusty
down the Colorado River valley Tuesday afternoon, but otherwise
fairly light for the remainder of the week. A period of more
unsettled wet weather may begin to encroach on the region late next
week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports of wind and dust may be needed in SE California
Sunday, while snow reports may be needed in Gila County Monday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...CB/Hernandez/MO
AVIATION...Hirsch
FIRE WEATHER...MO
Area Forecast Discussion
National Weather Service Sacramento CA
945 PM PST Sat Nov 26 2016
.SYNOPSIS...
An incoming storm will bring rain to the valley and snow to the
Sierra tonight through Sunday afternoon. A second system moves
into NorCal late Sunday night into Monday with drier conditions on
Tuesday.
&&
.Discussion...
Short wave energy near the SWrn ORE and NWrn CA coast is beginning
to re-enhance precip over interior Norcal this evening. This short
wave is forecast to drop SEwd over the CWA tonight...continuing
widespread precip over the area. With snow levels down to around 3k
ft over the Sierra, more accumulating snow will occur over the
roadways with an additional 8-12 inches over the Sierra mostly from
the 06z-12z Sun time period possible. This would put BLU over a foot
of snow during the 18z hr period. With expected snowfall rates from
1 to 3 inches per hour over the I-80/US-50 corridor overnight with
the incoming short wave energy we upgraded the advsry to a warning
for zone 69.
Radar shows some rain shadowing in the Shasta Co area but this could
be a matter of beam overshooting. MesoWest shows mostly several
hundredths of an inch occuring per hour with snow levels down to
around 2500 ft.
Higher resolution QPF progs suggest the precip will be winding down
in our CWA by 16z-18z Sun. By Sun afternoon, travel conditions
should improve rapidly during the return home from the long holiday
weekend. JHM
.Previous Discussion...
Model analysis and water vapor imagery indicated a high amplitude
trough of low pressure moving across California during the early
afternoon hours. Radar imagery indicated a north to southward
oriented area of rain and snow along the foothills of the Sierra.
Elsewhere across the forecast area, overcast conditions were
present with temperatures ranging from the upper 40s to lower 50s
in the Valley.
The NAM and HRRR model forecasts seem to be handling the current
radar trends the best with a band of rain against the Sierra with
a dry area over the valley for an hour or two, and then another
area of precipitation moving into northern California from the
coast. If the precipitation stays on track as expected, widespread
areas of 5 to 10 inches of snow in the Sierra will result by late
Sunday morning. A winter weather advisory is still in effect
through Sunday morning with slippery roadways and low visibility
in falling snow. Traveling could become difficult and chain
controls could become likely for the mountain passes, so traveling
is discouraged unless necessary.
Snow and rain will briefly end on Sunday before the next round of
precipitation moves into northern California Sunday night through
Monday morning. Additional snowfall between 1 and 2 inches is
expected for elevations higher than 3500 feet.
Once precipitation tapers off Monday morning, a period of dry
weather will last through Tuesday night. Temperatures across the
forecast area will remain near normal in the 50s for the
Valley/foothills and 30s/40s for higher elevations.
&&
.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
A shortwave trough is expected to move into the Pacific Northwest
by mid-week. Model guidance is coming into better agreement
regarding the details of this system, but the ECMWF is still
the fastest solution. This system might bring a chance of showers
for the northern portions of our CWA on Wednesday, but dynamics
do not look that impressive. GFS and ECMWF dig this low into the
Great Basin Thursday, with possible lingering Sierra showers under
cyclonic flow. Ridge aloft builds across the region late next
week. This should result in dry conditions and daytime highs
around 3-7 degrees above normal.
&&
.AVIATION...
MVFR/IFR conditions expected across TAF sites as a storm system moves
into interior Norcal. IFR ceilings/visibilities over Sierra
overnight as heavy snow showers move through the area.
Precipitation should persist across TAF sites generally through
12z-15z Sunday timeframe. Southerly winds to 15 knots in the
valley with gusts to 30 knots over higher Sierra locations.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 4 AM PST
SUNDAY FOR SHASTA LAKE AREA / NORTHERN SHASTA COUNTY...
Winter Weather Advisory until 10 AM PST Sunday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
Winter Storm Warning until 10 AM PST Sunday for West Slope Northern
Sierra Nevada.
Winter Weather Advisory until 10 AM PST Sunday for Burney Basin/
Eastern Shasta County.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
301 AM CST Sun Nov 27 2016
.SHORT TERM...(Today and tonight)
Issued at 259 AM CST Sun Nov 27 2016
Early this morning an intense upper trough was located across
western AZ and will lift northeast into the central plains Today and
this evening. A secondary upper trough will follow behind the main
upper trough and move into far west TX by 12Z MON.
A 40 to 50 KTS LLJ early this morning extended from west central TX,
northeast across KS and was transporting deeper gulf moisture
northward. Forecast soundings show a deep dry air layer above 800mb,
thus at this time the increasing isentropic lift on the 295 theta
level should not cause any thunderstorms due to the dry layer of air
and EML. I cannot rule out some light showers or drizzle developing
through the morning hours. By afternoon the stronger ascent ahead of
the upper trough will cool and moisten the mid levels of the
atmosphere. The elevated showers and thunderstorms should remain
elevated through most of the afternoon hours across the CWA. Several
of the higher resolution models show a break in the showers and
scattered thunderstorms during the mid and late afternoon hours.
Farther northwest of the CWA across northwest and west central KS a
dry line will push east from western KS and a surface cold front
will begin to push southeast into northwest KS. The NAM and WRF
solutions show the better instability developing in the afternoon
hours across west central KS. The most robust MLCAPE values of
around 400 j/kg will be centered from the Hill City, KS area
northward to the NE border. The vertical windshear will be strong
across west central KS with 0-6KM effective windshear of around 50
KTS. The low-level 0-1KM SRH will be between 200 and 300 j/kg. If
surface based storms can develop along the dryline and front
intersection across west central and northwest KS during the
afternoon hours they may evolve into low-top supercells. However the
instability is rather weak and the vertical windshear may inhibit
any deep moist convective updrafts from developing. Gradually the
instability axis of 200 to 300 J/KG will shift east into the western
counties of the CWA. If there are any isolated storm ongoing they
may move into the western counties during the early evening hours.
Though the tendency after sunset will be for these scattered surface
based storms to become elevated. I suppose with any low top
supercell there may be small hail, a possible severe wind gust and
perhaps a isolated weak tornado if any low top supercell can remain
surface based while entering into the western counties of the CWA
this evening. IMO, I think the storms will become elevated and will
only provide a chance for small hail and gusty winds while moving
into the western counties of the CWA after 00Z. The better chance
for any severe low top supercells will be west of the TOP CWA during
the afternoon hours. The WRF solutions show only a line of surface
based storms developing southwest of Hill City northeast into south
central NE, and these storms remaining northwest of the CWA during
the late afternoon and early evening hours. There may be some
elevated thunderstorms across most of the CWA but unless they become
surface based they will not be severe. Farther east across the CWA
the MLCAPE values drop off to less then 50 J/KG even though the low-
level shear remains strong with 400-500 J/KG of 0-1KM SRH.
As the H5 trough lifts northeast into the central high plains, a
lee surface low will deepen across eastern CO and western KS.
The tightest surface pressure gradient will develop across west
central KS during the early afternoon hours, and shift northeast into
south central NE. Sustained surface winds across north central KS
will increase to 25 to 30 MPH with gust to 40 MPH and continue into
the afternoon hours. The south central counties will see similar
winds developing through the afternoon hours. It looks as if the
cloud cover will hold through the afternoon, so I do not expect
dry adiabatic mixing to be much above 900mb. Therefore I don`t think
a wind advisory will be needed for the CWA Today. It will be windy,
especially southwest of a Emporia to Concordia line where wind
speeds may come close to having 30 MPH sustained winds with some
gusts of 40 to 45 MPH. Northeast and east central KS will see
southerly surface winds increase through the morning hours to 15 to
25 MPH with gusts of 35 MPH possible through the afternoon hours.
Overall, it will be a windy day across the CWA.
Cloud cover should keep highs in the mid and upper 50s. There may be
some lower 60 degree readings across the southwest counties of the
CWA.
Tonight, if a line of elevated storms develop they will move through
the CWA during the evening hours and should be southeast of the CWA
after midnight. Once again the best chance for a few strong storms
will be in the early evening hours across the western counties of
the CWA. Though the higher resolution models such as the WRF and RAP
keep the stronger surface based storms northwest of the CWA during
the afternoon and early evening hours. Once the lead H5 trough lifts
northeast of the CWA the 850mb winds will veer more to the southwest
and the western edge of deeper gulf moisture will translate east
into MO.
.LONG TERM...(Monday through Saturday)
Issued at 259 AM CST Sun Nov 27 2016
Another quiet weather period for the work week into next weekend
with no precipitation expected. The upper low system continues to
track north on Monday bringing slight WAA in the morning, and
neutral advection towards the afternoon. This leaves northeast
Kansas with warmer than normal temperatures once again Monday, with
highs in the upper 50s and low 60s. The system shifts east Tuesday
bringing northwest flow back to the area and moderating temperatures
back to near seasonal values. Wednesday onward, conditions remain
relatively similar with high temperatures in the mid 40s and lows in
the 20s. The next upper level system moves into the northwest US
Thursday morning; however, this system is progged to move south and
cut off from the mean flow leaving northeast Kansas in relatively
zonal flow beginning Friday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1127 PM CST Sat Nov 26 2016
VFR conditions are expected through 11Z with a transition from
mvfr to ifr as low level moisture increases northward. Winds will
increase to around 16kts with gusts to 25 kts by 15Z then
increase to around 21kts with gusts to 32kts around 18Z. MVFR
vsbys with showers are possible after 18Z along with vcts.
Precipitation potential should end in the 02Z-04Z Monday time
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...Heller
AVIATION...53
Area Forecast Discussion
National Weather Service Albany NY
1011 AM EST Sun Nov 27 2016
.SYNOPSIS...
For today, an upper level trough will bring clouds and some lake
effect rain and snow showers to our area. On Monday, high pressure
will bring sunny and cold conditions. Milder temperatures and wet
weather are forecast through the middle of the week, before winter
returns next weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 1011 AM...most of the forecast area is overcast and
cold. Temperatures are generally in the 30s with some 20s in the
higher terrain. Winds are from the northwest at 5 to 10 MPH and
gusting at times to around 20 MPH making it feel colder. Radar
shows a rather wide plume of light lake effect showers extending
from lake Ontario southeast to the western Mohawk Valley, eastern
Catskills and mid Hudson Valley. Web cameras show some snow
showers in the hills while valley locations have reported some
light rain showers. Latest HRRR shows this plume continuing today
before gradually drifting southwest of our area. Model moisture
fields show high RH through the daylight hours so our clouds will
probably break up after sunset this evening.
Near seasonal temperatures will highs in the lower 30s across the
western Adirondacks to the mid/upper 40s in the mid Hudson
Valley. Northwesterly winds will add a chill.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
The ridge builds in at all levels of the atmosphere tonight. The
surface high will begin to shift offshore Monday while the ridge
axis aloft crests across the region. Cloud cover decreases tonight
and winds diminish which will allow temperatures to drop into the
upper teens to upper 20s. Abundant sunshine Monday after days of
cloudy skies along with light/variable winds will make for a
rather pleasant day for many. Looking at high temperatures in
the mid 30s to upper 40s.
The forecast turns unsettled as we head toward the middle of the
week. The upper ridge will shift offshore Monday night into Tuesday
morning as large low pressure system which developed over the Plains
begins to impact region. A series of short waves moving onshore
along the west coast will have resulted in the development of broad
deep trough over the central portion of the CONUS by Tuesday with
a large stacked low pressure system over the northern Plains. The
storm will gradually move eastward into the western Great Lakes
Tuesday night.
Clouds increases Monday night with precipitation expected to
overspread the local area Tuesday morning as the system`s warm
front approaches. However, with a cold airmass in place at the
surface and warm air advection occurring aloft the stage will be
set for a period of mixed precipitation including freezing rain
and sleet Tuesday morning before a changeover to plain rain occurs.
Expecting early lows Monday night with temperatures stabilizing
then beginning to rise late at night/early in the morning. Based
on the expected surface temperatures as the precipitation arrives
a period of freezing rain and sleet may occur across the southern
Adirondacks into the Mohawk Valley, across the Lake George Saratoga
region and southern Vermont into the northern Berkshires. The
threat will last the longest across the southern Adirondacks and
southern Vermont. Temperatures during the day Tuesday are forecast
to rise into the lower 40s to lower 50s. The rain is expected to
tapering off in the evening.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Strong upper impulses rotating around the eastern periphery of
strong upper energy in the central U.S. will increase warm
advection, low level jet forcing and isentropic lift over our region
Wednesday and Wednesday night. There is an increasing consensus
that coverage of rain will be spotty Wednesday morning but increase
in coverage through Wednesday afternoon. Highs Wednesday in the
lower to mid 50s but upper 40s northern areas.
Tight boundary layer thermal gradient, strong low level jet forcing
and primary upper energy track through the region Wednesday night
and Thursday with the cold frontal passage during the day Thursday.
The mean upper trough axis also shifts over and just east of our
region, helping cold advection to spread across our region through
the weekend.
Rain likely through much of Thursday and when the front tracks
through coverage of rain will decrease to scattered showers. Highs
Thursday just a degree or two cooler than Wednesday, with possibly
more rapid cooling Thursday afternoon depending on the timing of the
frontal passage.
Total rainfall through Thursday still looks to be enough where
any snow melt in higher elevations could contribute enough to run
off that we will just have to watch how rivers respond. It has
been quite dry in past months but vegetation is not soaking up
water this time of year. MMEFS suggests no problems but some areas
just west of our area are showing the potential to perhaps get
solidly into action stage.
Cold advection deepens Thursday night through the weekend. Strong
low level winds off the Great Lakes should support lake effect snows
in the western Mohawk Valley and southern Adirondacks. Isolated to
scattered snow showers are expected through areas along and north of
the Mohawk Valley due to the west northwest winds, with some
possible slight enhancement in the Taconics, southern Green
mountains and northern Berkshires. Some lingering trailing upper
energy could also support slightly better coverage of rain and snow
shower activity.
During the day Friday and Saturday, temperatures could get warm
enough for rain to mix in with the snow showers. Highs Friday in
the 40s but 30s in the southern Adirondacks and southern Green
mountains. Highs Saturday in the lower to mid 40s but lower to mid
30s southern Adirondacks and southern Green mountains.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Weak high pressure is building in and low level moisture is being
scoured out of the region. Ceilings and visibilities have increased
to VFR everywhere and scattered clouds below 3000 feet should mix
out through the morning. There will still be a ceiling above 3000
feet most if not all of the day and visibilities will stay VFR as
well.
By late this afternoon or evening indicating broken cloud layer but
there could be periods of scattered late this afternoon through
tonight. More drying is expected through the night to minimize any
fog potential.
Nearly calm winds through about 14Z will become northwest at near 10
Kt and could become gusty to just over 15 Kt at KPSF, KALB and KPOU.
Winds become light this evening and tonight.
Outlook...
Monday Night: Moderate Operational Impact. Chance of RA.
Tuesday: High Operational Impact. Definite RA. Chance FZRA early am.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...RA.
Wednesday: Moderate Operational Impact. Chance of RA.
Wednesday Night: High Operational Impact. Likely RA.
Thursday: High Operational Impact. Likely RA.
&&
.FIRE WEATHER...
High pressure will gradually begin to build in from the
west today diminishing the lake effect showers. Abundant sunshine
for Monday as the high moves over the region. Milder temperatures
through the middle of the week, however the weather will be
unsettled and wet as a low pressure system approaches and moves
across the region.
&&
.HYDROLOGY...
Diurnal snow melt will continue through into Monday night, however
a widespread rainfall along with mild temperatures are expected
Tuesday into Thursday as a large complex low pressure system
impacts the region. The precipitation is expected in two rounds
one Tuesday then another Wednesday night/Thursday.
Total rainfall through Thursday still looks to be enough where
any snow melt in higher elevations could contribute enough to run
off that we will just have to watch how rivers respond. It has
been quite dry in past months but vegetation is not soaking up
water this time of year. MMEFS suggests no problems but some areas
just west of our area are showing the potential to perhaps get
solidly into action stage.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...IAA
NEAR TERM...IAA/SND
SHORT TERM...IAA
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...IAA
HYDROLOGY...IAA/NAS
Area Forecast Discussion
National Weather Service Dodge City KS
630 AM CST Sun Nov 27 2016
...UPDATED AVIATION SECTION...
.UPDATE...
Issued at 303 AM CST Sun Nov 27 2016
Increased coverage of showers and measurable rain in the forecast
through this morning. Increased the pops, given the consistency of
the HRRR and after coordinating with WFOs GLD/AMA. Starting to
look like a fast-moving band of showers will race across the CWA
this morning. Stratus will spread quickly NW through sunrise, as
seen with the falling ceilings at Pratt, along with areas of
drizzle.
&&
.SHORT TERM...(Tonight through Sunday Night)
Issued at 1230 AM CST Sun Nov 27 2016
Active weather expected across SW KS today, with the primary
concern being strong to damaging winds, both with and outside of
any convection.
Moisture advection is underway this morning, both in the lower and
upper levels, as subtropical moisture is tapped and what limited
gulf moisture there is streams north with the low level jet.
Stratus ceilings will overspread SW KS through sunrise, with areas
of drizzle likely. Elevated south winds should keep the boundary
layer mixed and prevent fog formation.
HRRR solutions generate showers and convection over NE New Mexico
by 6 AM, and then spreads this activity NE into SW KS this
morning. ECMWF also generates QPF signals during the 6am-noon
time frame as intense jet dynamics begin to interact with
moist/warm advection. For these reasons, began scattered pop
coverage for showers/isolated thunder/drizzle starting immediately
at 6 AM and continued them through noon.
Strong shortwave currently near Las Vegas and the Grand Canyon
early this morning will be near the Four Corners near sunrise.
This shortwave will race NE, with a pronounced negative tilt,
arriving at the CO/KS border around noon, and central Nebraska
around sunset this evening. Strong surface cyclogenesis will
result north of SW KS, accompanied by very strong SW winds this
afternoon. Sharp dryline will advance west to east quickly
after noon, in response to strong cyclogenesis to the north.
Dryline is expected to reach Dodge City roughly around 1 pm.
West of the dryline this afternoon, intense SW winds will develop,
with frequent gusts of 45-55 mph. Included areas of blowing dust
in the grids. GFS soundings for 3 pm in the dry sector show the
boundary layer mixing dry adiabatically to near 650 mb/9k ft,
where flow is forecasted to be about 60 mph. As such, wind gusts as
strong as 60 mph are certainly possible. Forecast soundings still
show 45 mph at about 500 feet this afternoon, so gusts that strong
are a certainty. Do not have enough confidence to hoist a high wind
warning, but it will be close. Strongest winds are expected 1-5 pm,
with winds quickly diminishing through sunset.
That said, SW/W winds will continue to gust over 30 mph well into
the evening hours.
East of the dryline this afternoon, scattered showers and
thunderstorms are expected, with coverage favoring the eastern and
NE zones. HRRR output and other CAMs show cellular convection
(perhaps low-topped supercells) over the NE CWA 2-4 pm, SE of the
deepening surface low. Clearly, moisture and instability will be
highly limited. That said, any convective element will enhance
momentum transfer to the surface and will increase the risk of
damaging winds (even if the thunderstorm itself is meager). Any
rain showers or virga shafts will possess the potential for wind
gusts over 60 mph. Per coordination with SPC, the 5% marginal wind
risk continues for the northern zones this afternoon.
Tonight...Clear with slowly diminishing W/SW winds as cyclone`s
dryslot invades SW KS. Much drier air would argue for stronger
radiational cooling tonight, but mixing winds and a downslope
component should low temperatures Monday morning generally in the
30s.
.LONG TERM...(Monday through Saturday)
Issued at 200 AM CST Sun Nov 27 2016
Another extended period of quiet and (unfortunately) dry weather
is coming to SW KS. Powerful 522dm closed low in the Dakotas on
Monday will only slowly meander eastward through the Great Lakes
through Thursday, keeping us in dry and cool, subsident NW flow.
No hope of any precipitation in this pattern, and the forecast is
dry. Temperatures will certainly feel like the season, restricted
mainly to the 40s in the afternoons, and well below freezing at
night. NW winds will increase each afternoon Tuesday and
Wednesday, adding to the chill.
A closed low diving south through Nevada on Thursday will sink all
the way to Baja California on Friday. 00z ECMWF buries this closed
low well into Mexico through next weekend, keeping any rain/snow
well SW of SW KS. Operational GFS/superblend is very similar, but
is a bit more optimistic, with some light snow entering SW KS
early Saturday, as the closed low`s deformation clips the region.
Even the GFS storm track would keep the vast majority of
meaningful (and needed) precipitation south of us in Texas next
weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 621 AM CST Sun Nov 27 2016
Ceilings have begun to develop as stratus moves north along an
impressive low level moisture transport axis into southcentral
Kansas. These ceilings will remain in the area until the afternoon
when westerly downslop flow develops and rapidly warms the area.
In the meantime, scattered showers will increase in coverage
through the morning hours, with potential for thundertorms as
well as the day progresses. Strong southerly flow will only
increase into the late morning with wind speeds maxing out in the
early to mid aftenoon with gusts to near 40 knots.
&&
.FIRE WEATHER...
Issued at 200 AM CST Sun Nov 27 2016
Will maintain red flag warning as inherited for this afternoon.
After a period of low clouds, drizzle and a few rain showers this
morning, rapid drying and very strong SW winds are expected behind
a dryline this afternoon. Relative humidity will fall to 10-20%
from 1-5 pm, as SW winds gust near 50 mph. With moderate drought
and widespread cured/dry fuels, the risk of wildfire spread,
should an ignition occur, warrants the red flag warning. The most
critical time period of strong winds and low RH behind the dryline
will be from 1-5 pm, before W/SW winds begin relaxing around
sunset, and relative humidities slowly recover. Fire managers and
crews in the fields should monitor for any ignitions this
afternoon; extreme fire behavior is possible.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 70 35 59 29 / 50 0 0 0
GCK 66 32 57 27 / 50 0 0 0
EHA 63 33 55 28 / 60 0 0 0
LBL 68 32 58 27 / 60 0 0 0
HYS 65 36 57 30 / 40 10 0 0
P28 63 40 62 33 / 40 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM CST /noon MST/ this afternoon to 7 PM
CST /6 PM MST/ this evening for KSZ043>045-061>064-074>078-
084>088.
&&
$$
UPDATE...Turner
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Russell
FIRE WEATHER...Turner
Area Forecast Discussion
National Weather Service Wilmington NC
938 AM EST Sun Nov 27 2016
.SYNOPSIS...
Dry high pressure building in will move offshore on Monday. A
warm front will cross the area early Tuesday followed by warm
temperatures, breezy south winds, and scattered showers through
mid-week. A cold front passage will bring clearing skies late
Thursday into the upcoming weekend, with seasonably cool
temperatures.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 935 AM Sunday...Temperatures rapidly rising this morning
through the 40s and with plenty of sun and weakening CAA expect
we will be well in the 50s shortly. Forecast in good shape with
no changes needed. Previous discussion follows:
A crisp start early this morning will undergo 25-30 degree
temperature rises today as continental high pressure moves into
the area, offering near cloudless skies and low humidity levels.
The air-mass remains resident into Monday so another chilly
overnight period tonight can be counted on. High clouds from an
upstream wave will stretch into the region late tonight, which
may impede ideal longwave heat escape into the pre-dawn hours.
Minimums daybreak Monday 33-37 inland, around 40 by the coast.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Primary headliner this period `increasing
rain chances` into Tuesday as short-wave energy ahead of a cold
front picks up a moisture tap. Monday expect mainly clouds as the
dry continental air mass holds on, but erodes into late Monday. A
1/4 inch or less of rainfall expected Tuesday. The strong warm
air advection will bring soaring temperatures well above normal
Tuesday into the upper 70s mixed with the showers, and balmy,
gusty wind of 20 to 30 mph in the afternoon Tuesday.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 330 AM Sunday...Wednesday will be the warmest day of this
period with widespread 70s for highs, possibly a few 80 degree
marks depending on the extent of the cloudiness and possible
pcpn. Wed starts out with an amplified pattern aloft with
ridging and its axis having moved off the East Coast of the U.S.
while a cutoff low over the north central U.S.takes shape. The
tapping of the Gulf of Mexico and the Atlantic will provide the
necessary moisture for clouds and pcpn. The upper cutoff low is
progged by models to push east to and across the Great Lakes by
midday Thu. A decent vort or midlevel s/w trof will rotate
around the cutoff low will bottom out around Louisiana early
Wed then lift NE to the Mid-atlantic and NE states by late Thu
morning. The direct dynamics from this vort stays west and north
of the ILM CWA, however, 300mb jetstream dynamics indicate the
SE U.S. and the mid-Atlantic area will be on the RR Quadrant of
this upper jet, meaning decent UVVS will occur. And this so
happens to As of 3 AM Sunday...Primary headliner this period
`increasing rain chances` into Tuesday as short-wave energy
ahead of a cold front picks up a moisture tap. Monday expect
mainly clouds as the dry continental air mass holds on, but
erodes into late Monday. A 1/4 inch or less of rainfall expected
Tuesday. The strong warm air advection will bring soaring
temperatures well above normal Tuesday into the upper 70s mixed
with the showers, and balmy, gusty wind of 20 to 30 mph in the
afternoon Tuesday. take place Wed night thru early Thu just
prior to the sfc cold frontal passage. Thus will have frontal
dynamics, jetstream dynamics and a progged SSW to SW 40 to 50 kt
low level jet at less than 1k feet via GFS Bufr soundings. All
of this points to a decent shot of pcpn Wed aftn thru Thu
morning. PCPN type will primarily be showers with isolated
thunderstorms. The convection will depend on the availability of
instability. In other words, the convection threat will come
from high shear and low Cape scenario. Have continued to
illustrate isolated convection during that time frame until the
CFP early Thu. The isolated severe threat still looks too low to
mention in the forecasts at this time.
After the CFP, look for slowly improving conditions later Thu
thru Fri. The CAA surge and clearing skies will lag well behind
the cold front, likely occurring Thu night and Fri. Thus, Thu
max temps could again reach 70+ degrees with partly to variably
cloudy skies. For Fri and Sat, a return back to normal climo
temperatures with around 60 for highs and upper 30s to around 40
for lows under mainly clear skies.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
As of 12Z...VFR/no sig weather expected this 24 hr TAF period.
Nearly clear skies today. Calm winds early this morning will become
NW-NE 5-8 kts. This afternoon at KCRE/KMYR winds will become E-SE,
and will likely become light and variable aob 5 kt at KFLO/KLBT as
the center of high pressure moves in.
By late afternoon winds will become light and variable at all
terminals. overnight high clouds will increase ahead of the next
approaching system.
Extended outlook...Tempo MVFR from scattered showers Tue. Chance IFR
early Wed. Tempo MVFR/IFR from numerous showers/isolated
thunderstorms late Wed thru Thu morning. Otherwise VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 935 AM Sunday...Latest obs show seas of 3 to 4 ft and
light northerly winds. Winds easing off earlier than anticipated
so may be revising sea heights for the near term forecast
downwards with the next update. Previous discussion follows:
ENE waves 3-5 feet every 6-7 seconds highest offshore and gusty
N winds early this morning will prevail at least through the
morning. The gusts will ease this afternoon as the surface high
migrates a bit closer to the coast. Sea heights accordingly will
ease gradually by a foot or 1.5 ft later today, thus an
improving marine trend on tap through the near term period.
Winds to lighten and veer onshore into early Monday as the high
center nears the Outer Banks. No TSTMS or VSBY restrictions
expected this period.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Chief concern this period is worsening
marine conditions into Tuesday as southerly winds increase ahead
of an upstream low pressure system. Small Craft Advisory
Conditions appear likely sometime on Tuesday as seas build to
6-8 feet every 8 seconds by Tuesday evening offshore. Marine
showers can be expected Tuesday and gusty S winds of at least 25
KT. A few TSTMS are possible offshore tuesday.
LONG TERM /WEDNESDAY THROUGH THURSDAY/...
As of 330 AM Sunday...Looking at SCA conditions likely for both
days. Wed will be the 2nd day of strong SSE to SSW flow at 15 to
25 kt. Depending on local SSTS, winds of 30-40 kt just off the
deck, could mix down to the ocean sfc as Gale force gusts Wed
aftn thru early Thu morning. The chance for convection will
occur ahead of the cold front from Wed aftn thru Thu morning,
the latter time is when the cold front pushes offshore. The sfc
pg loosens during Thu allowing wind speeds to diminish-some.
Significant seas will become fully risen under the strong SSE-
SSW flow during Wed, with 5 to 8 ft likely, up to 9 ft outer
waters especially off Cape Fear where the onshore flow will help
push in higher SSTs across a portion of the ILM coastal waters
enabling those stronger wind gusts to possibly mixing down to
the sfc. Periods will run from 7 to 8 seconds, ie. a pseudo or
fresh swell. With an offshore wind direction during Thu, seas
will only slowly subside to 3 to 6 ft by the end of the day,
Thu.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
NEAR TERM...MJC/REK
SHORT TERM...MJC
LONG TERM...DCH
AVIATION...MRR
MARINE...DCH/MJC/REK
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
524 AM CST Sun Nov 27 2016
.UPDATE...
523 AM CST
Meteorologically, it is an absolutely fascinating evolution of
the stratus this morning. Area of LIFR stratus and fog has
developed over NC IL and what`s so interesting is that this
appears to be developing as a result of the ever so slight
orographic ascent. Hi-res topography imagery shows that this
stratus is developing on the plateau, clinging to the plateau and
being advected north off the highest terrain. In 10+ years of
forecasting here, this is the first time I can recall orographic
lift resulting in stratus and fog!
In addition to that area, which is likely to persist and perhaps
expand a bit east and west as it spreads north, also expecting
stratus over central IL to continue developing and advecting north
early this morning. A bit more confident than earlier than most of
the CWA will be stratus covered by midday. Will likely also see
some fog beneath the stratus and with some guidance hinting at
fog becoming more prominent and dense after sunrise, have added
some fog to the grids through late morning now as well. Finally,
with some increase in confidence in the cloudiness conditions
today, opted to shave a couple more degrees off high temps.
Grids have been updated, text products will follow shortly.
Izzi
&&
.SHORT TERM...
257 AM CST
Through tonight...
The million dollar question on which today`s entire forecast
hinges is what will the stratus do. GOES rapid scan requested this
morning is showing the band of IFR stratus over eastern MO/western
IL making steady progress northeastward, with recent imagery also
showing some expansion in the areal coverage. MOS really not very
bullish with CIGS today, but the HRRR has been depicting this area
developing and advecting northeast into and across our CWA this
morning. Have trended the grids/forecast in that direction today,
shaving a few degrees off high temps and expanding the overcast
skies northeast to encompass most of the area by early afternoon.
This is far from a sure thing and anywhere that doesn`t get socked
in with stratus will likely see temps several degrees warmer than
current forecast. Probably not going to be much time this
afternoon for stratus to erode before extensive mid-high level
cloudiness overspreads the area in advance of first wave of rain
with huge deep low over the northern/central plains.
Band of rain, some of it probably falling at a good clip, will
spread across the area this evening. Still looks like 1/3" to
locally 3/4" of rain will fall tonight with this band, the back
edge of which should clear our eastern CWA before sunrise Monday
morning.
Izzi
&&
.LONG TERM...
257 AM CST
Monday through Saturday...
Monday looks to be dreary, breezy, and damp. Pronounced mid-level
drying in the wake of the first wave should result in little if
any meaningful precipitation through much of the day. Saturated
low levels, modest ascent, and collision and coalescence within
the stratus deck should support drizzle and fog. Fog could
actually grow potentially dense in the afternoon as dewpoints
creep up and temps remain locked close to 50.
Dense fog chances will be lesser across about the SE half to
third of the CWA Monday afternoon where another wave pivoting
around the big cut off low will result in an another period of
steady, healthy rainfall late Monday afternoon through Monday
evening. Showers should increase in coverage area wide Monday
evening as yet another spoke of vortcity pinwheels around the
low.
Both of these waves should clear the area prior to dawn Tuesday
and guidance is in good agreement in really substantial drying of
the entire column with forecast soundings strongly suggesting
skies becoming mostly sunny. The sunny skies within the windy,
warm sector of this cyclone should allow temperatures to respond
quite nicely. Local 925mb temp climatology suggests that we could
threaten 60F for highs Tuesday, with at least mid-upper 50s
looking like a lock if lingering cloud cover isn`t an issue.
Colder air mass will begin filtering into the area in the wake of
a cold front Tuesday night. Still looks like little fan fare with
the front, but a gradually cooler air mass will spill into the
area Wednesday. At some point Wednesday, would anticipate CAA
stratus to rotate into the area and begin what looks to be a
potentially long period of cloudy skies.
Deep cyclonic flow with moisture trapped beneath frontal inversion
should lead to day of day of cloudy skies and small diurnal temp
swings starting Wed night and continuing into next weekend. Will
need to watch for any subtle shortwave that could pivot around
this cut off low, as any one of them could produce some light snow
showers, though temps at this point look like they`d be too warm
for any accumulation. Kept the forecast dry for now, but something
to keep an eye on in coming days.
Izzi
&&
.AVIATION...
For the 12Z TAFs...
Watching two areas of stratus. The first is in between ORD and RFD.
Based on satellite, it looks like the stratus will only impact DPA.
The second area is spreading north across central IL.
Timing has the stratus reaching the terminals late this morning to
around noon. Kept 1000 ft cigs, but confidence is low in the exact
cig height. Thinking IFR cigs will rise to MVFR and scatter out to
VFR this aftn as south winds increase. South gusts to 25 kt are
expected this evening through Monday morning.
Rain spreads from west to east this evening. Steadier rain will
bring vsby down to arnd 3SM and cigs to IFR. Rain becomes drizzle
early Monday morning and cigs rise back to MVFR. Have low
confidence in how long vsby will remain MVFR and cigs remain IFR
Monday morning.
JEE
&&
.MARINE...
209 AM CST
Headlines...Upgraded the gale watch to a warning for the open waters
and IL nearshore waters. Timing remains the same, this evening into
Monday night. Confidence is lower in gales occurring over the IN
nearshore waters, so left those under a Gale watch. A few gales may
occur, but not sure if they will be frequent enough to warrant a
gale headline. Also pushed back the start time of the gale watch for
the IN NSH waters to early Monday morning.
High pressure over the Ohio valley continues east, and the next low
develops over the plains this evening. The low deepens rapidly as
it reaches the Dakotas Monday. As such, south to southeast winds
increase to gales tonight. The low weakens slightly as it shifts
over Minnesota Tuesday morning, and its cold front swings over the
lake early Tuesday morning. Winds become southwest at 30 kt behind
the front, and there could be a couple gale force gusts to 35 kt
over the northern half of the lake. The low continues to weaken and
slowly shift east across the Great Lakes through late this week.
Winds will be southwest to west, and then become northwest Friday
behind the low.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ777-LMZ779...9 PM Sunday
TO 3 AM Tuesday.
Gale Watch...LMZ743-LMZ744-LMZ745...3 AM Monday TO 3 AM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Miami FL
1004 AM EST Sun Nov 27 2016
.UPDATE...
The Atlantic coastal waters have been busy in terms of showers
and thunderstorm activity during the morning hours with radar data
showing additional showers developing over Key Biscayne and South
Miami Beach. However, conditions in general remain dry over land
across much of South Florida as a weak cold front boundary keeps
moving southward across the area. Winds are expected to begin
veering to northeast during the afternoon and evening hours,
along with a slightly drier and cooler air mass descending upon
the region in the wake of the FROPA.
High pressure and generally benign weather will prevail through
midweek.
&&
.PREV DISCUSSION... /issued 717 AM EST Sun Nov 27 2016/
AVIATION...
A cold front moving south across the area is generating showers
and a few thunderstorms over the nearshore Atlantic coastal
waters and along some coastal locations. The current forecast
continues to keeps this activity mainly offshore, with VFR
conditions prevailing at all TAF sites through the TAF period.
Even though there is no weather in the TAFs, some of the Atlantic
coastal area sites may experience an isolated shower through
tonight.
PREV DISCUSSION... /issued 423 AM EST Sun Nov 27 2016/
DISCUSSION...
At 400 am, doppler radar continued to show scattered showers,
with isolated thunderstorms, slowly dropping southward along
portions the Atlantic coastal waters. The latest HRRR and WRF
model runs prog this activity to skim the coastline, so a slight
chance of showers for the east coast metro region appears
warranted. The surface analysis this morning indicated a weak
front draped from east to west across the CWA. As this front
pushes south today, the overall flow pattern will begin to shift
to the northeast, ushering in slightly drier and cooler air.
Maximum temperatures may only top out in the upper 70s along the
east coast, to around 80 degrees inland.
On Monday, as high pressure builds to the north of region, winds
will continue to shift to the east/southeast and become breezy at
times. Maximum temperatures will remain similar to todays with
upper 70s along the east coast and near 80 degrees inland.
Lingering isolated light showers will be possible over the
Atlantic waters Monday night, but generally dry over the land. By
mid week, a warming trend will develop, as pressure heights aloft
increase. Maximum temperatures Wednesday and Thursday will range
from the low to mid 80s across the entire region, around 5 degrees
warmer than normal for this time of year.
Thursday into Friday morning, both the GFS and ECMWF push yet
another weak cold front southwards towards southern Florida. Ahead
of this feature, moisture and instability appear sufficient enough
to include a slight chance of scattered showers over our region.
MARINE...
A weak front dropping southward over the Atlantic waters this
morning will continue the threat of scattered showers, with a
slight chance of thunderstorms. Winds will be shifting to the
northeast later today, then easterly and breezy by Monday. Small
craft advisories are in effect from this evening through Monday
evening for gusty east winds 15-25 kt and seas 5-8 feet
developing along the the Gulf Stream.
BEACH FORECAST... There will be a moderate rip current risk today
along the east coast beaches. This will likely transition to a
high risk beginning Monday, due to increasing onshore flow. &&
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 79 71 81 73 / 20 10 10 20
Fort Lauderdale 80 71 80 73 / 20 10 10 20
Miami 80 69 81 72 / 20 10 10 10
Naples 81 64 84 67 / 10 10 10 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 1 AM to 1 PM EST Monday for AMZ651-671.
Small Craft Advisory from 7 PM this evening to 7 PM EST Monday
for AMZ650-670.
GM...None.
&&
UPDATE...17/AR
Area Forecast Discussion
National Weather Service Norman OK
1004 AM CST Sun Nov 27 2016
.UPDATE...
Shifted rain chances westward this evening and tonight based on
trends in the observations and short term model guidance.
&&
.DISCUSSION...
It appears that the lead shortwave will be ineffective at
shifting moisture very far eastward this evening. Latest RAP and
HRRR show low level theta-e axis slowly moving eastward across
central Oklahoma late this evening and early tonight. As the next
shortwave trough (now evident in water vapor channel imagery over
Nevada) approaches later, cooling mid levels and a moist boundary
layer will contribute to up to around 1,000 J/kg MUCAPE late this
evening and early tonight. Although low level winds are expected
to veer, strong mid level flow will contribute to deep layer shear
of 60 knots or greater. Boundary layer should be weakly stable
which should limit wind/tornado threat, but given the amount of
momentum aloft the wind threat cannot be ruled out with the most
intense storms. A marginal wind/hail threat should increase across
central and southern Oklahoma by late evening and continue through
the night.
BRB
&&
.PREV DISCUSSION... /issued 557 AM CST Sun Nov 27 2016/
DISCUSSION...
The November 27-28, 2016 12 UTC TAF discussion follows:
AVIATION...
Overall, a low confidence aviation forecast through the TAF
period. Generally expect low ceilings with MVFR to IFR flight
conditions to continue at most terminals. Some drizzle and/or mist
is also possible. Gusty winds should prevent the development of
any low visibilities. Scattered showers, perhaps isolated
thunderstorms, are expected to develop across western Oklahoma
later this morning. These showers should progress eastward through
the day. Ceilings should improve across western terminals late
this afternoon; however, MVFR ceilings may persist across central
Oklahoma terminals through the period.
Windy conditions are also expected today, especially across
northern and western Oklahoma/adjacent north Texas. Expect
sustained south to southwesterly winds at 20 to 25 knots, with
gusts over 35 knots possible. Surface winds are expected to veer
and weaken tonight. The highest chance of showers/storms are
expected to stay southeast of any TAF sites tonight.
Mahale
PREV DISCUSSION... /issued 413 AM CST Sun Nov 27 2016/
DISCUSSION...
Primary forecast concerns are strong winds/rain chances today,
severe weather potential tonight, and the potential for
precipitation toward the end of the week.
A tight surface pressure gradient (~13 mb change in pressure from
Buffalo to Atoka at 21Z) indicates sustained wind speeds of 25 to
30 mph with higher gusts will be possible today, especially
across northern and western Oklahoma/adjacent north Texas. As a
result, went above blended guidance for wind speeds and opted to
issue a wind advisory. One mitigating factor, especially across
the east, will be cloud cover/precipitation. That should reduce
the potential for mixing. There will also be the potential for
elevated to near-critical fire weather conditions late this
afternoon. The overall threat will be modulated by how far
eastward the drier air shifts; however, parts of Harper and Ellis
Counties could experience these conditions this afternoon.
A fast-moving vort max is expected provide sufficient
ascent for showers and perhaps isolated thunder starting later
this morning across western Oklahoma and into northern/central
Oklahoma as it lifts northeastward this afternoon. Though the
forecast QPF is expected to be low (<= 0.10"), the probability of
receiving measurable precipitation is relatively high (>50%).
Therefore, opted to increase the probability of rain across
western Oklahoma late this morning and central/northern Oklahoma
this afternoon.
There might be a lull in precipitation late this afternoon into
the evening behind the initial wave. However, a second vort
max/short wave trough is expected to provide additional ascent
tonight--primarily across southeast Oklahoma. Environmental
conditions will be favorable for isolated strong to severe
thunderstorms as elevated instability increases after midnight.
Effective bulk shear and 0-1 km shear is expected to be more than
sufficient for strong to severe storms (both ~45 knots). The
limiting factor will be the instability. Nevertheless, MUCAPE
~750-1000 J/kg will be sufficient for elevated storms that could
produce hail. A stable boundary layer should mitigate the wind
threat, but with a rather intense low-level jet (>50 knots), some
higher momentum air/gusty winds could make it to the surface
within some downdrafts. Any rain chances should end Monday
morning across southeast Oklahoma.
For Tuesday through Thursday, relatively quiet weather is expected.
Embedded short-waves that will rotate around a cut-off mid/upper
level low across the Northern Plains will allow for reinforcing
shots of cold air to affect the Southern Plains.
For late Friday into Saturday, a mid/upper level low is forecast to
cut off across the southwest United States/northern Mexico.
Impacts will be modulated by the eventual location of the cut-
off low as the 27/00Z ECMWF is farther west than the 27/00Z GFS
with the system. Consequently, the GFS places Oklahoma and western
north Texas within a region of isentropic ascent late Friday into
Saturday. In contrast, the ECMWF holds off precip until late
Saturday into Sunday.
Impacts will also be modulated by the eventual temperature
profile. Overall, the GFS is cooler than the ECMWF (owing to the
GFS keeping a mid-level trough across the Northern Plains while
the ECMWF develops a ridge). For Saturday morning, GFS BUFR
soundings across northwest Oklahoma indicate that snow will be
possible if precipitation occurs. In this type of synoptic setup
(i.e., isentropic ascent/warm air advection), would anticipate a
mixture of precipitation types. However, for now, will just
include low chances of rain and rain/snow mixture to simplify the
forecast as the eventual transition zones will evolve as the
(possible) event draws closer. Only low chances were included
because of uncertainty as suggested by the drier/warmer ECMWF
solution.
Mahale
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 62 50 65 37 / 60 30 10 0
Hobart OK 64 43 63 36 / 60 20 10 0
Wichita Falls TX 66 51 67 43 / 30 30 10 0
Gage OK 67 38 62 29 / 60 10 0 0
Ponca City OK 61 49 64 34 / 60 30 10 0
Durant OK 62 57 69 44 / 30 80 50 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Wind Advisory until 6 PM CST this evening for OKZ004>007-009>012-
014>017-021-022-033>036.
TX...Wind Advisory until 6 PM CST this evening for TXZ083>085-087-088.
&&
$$
17/12
Area Forecast Discussion
National Weather Service Sacramento CA
805 AM PST Sun Nov 27 2016
.SYNOPSIS...
This weekend`s storm continues to bring snow to the Sierra
this morning but should move out of our region this afternoon. A
second system moves into NorCal late tonight into Monday with
drier conditions on Tuesday.
&&
.MORNING UPDATE...
Light snowfall was still occurring for some mountain locations
south of Highway 50, but short term HIRES guidance has indicated
the threat for additional large accumulations of snow has ended.
As a result, the Winter Weather Advisory and Winter Storm Warning
has been cancelled. However, slippery mountain pass roads and
chain controls may still be affecting travel today.
&&
.Discussion...
At 4 am, radar imagery showed that the remaining showers of the
current storm are near and south of the Interstate 80 corridor
from the Bay Area over to the Sierra. Chain controls and traffic
delays continue to impact Sierra travel down to around 3500 feet,
especially on I-80 and Highway 50. Any holiday travelers today
should check with CalTrans before going over the Sierra as the
Winter Storm Warning remains in effect through 10 am.
The HRRR and NAM models still indicate that the bulk of showers
should push southeastward this morning with precipitation
dissipating by late morning/early afternoon. Conditions should
improve between 10 am to noon.
Interior NorCal will see a break this afternoon and evening before
the next wave of precipitation moves inland late tonight into
Monday morning. This second wave won`t have as much moisture and
any additional snow accumulation should be light, up to 1 or 2
inches above 3500 feet. Rain amounts in the valley will also be
light at about a tenth of an inch or less. After showers end on
Monday, our region will see a period of dry weather through
Tuesday night. Temperatures across the forecast area will remain
near normal in the 50s for the Valley/foothills and 30s/40s for
higher elevations.
Models indicate that another weak wave could bring light
precipitation to NorCal on Wednesday. Once again, this should be a
light system and showers are expected to stay mainly at the higher
elevations with a slight chance in the northern Sacramento valley.
JBB
&&
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)
GFS and ECMWF dig upper low from Pacific Northwest into the Great
Basin on Thursday. Cyclonic flow over Sierra may allow for a few
showers over the crest through Thursday evening while rest of CWA
remains dry. Daytime highs Thursday will remain a little below
normal before a warming trend begins Friday as high pressure
pushes over the state. Warming continues on Saturday with daytime
max temperatures climbing to a little above normal at the end of
the week. Remainder of next weekend remains dry as upper ridge
flattens.
&&
.AVIATION...
MVFR/IFR conditions across TAF sites through about 15z as a storm
system moves through Norcal. IFR ceilings/visibilities over
Sierra through about 19z. Generally VFR conditions mid day today
through Monday morning. Variable winds generally below 15 know TAF
sites next 24 hours.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
...Update to aviation forecast discussion...
.SHORT TERM...(Today and tonight)
Issued at 259 AM CST Sun Nov 27 2016
Early this morning an intense upper trough was located across
western AZ and will lift northeast into the central plains Today and
this evening. A secondary upper trough will follow behind the main
upper trough and move into far west TX by 12Z MON.
A 40 to 50 KTS LLJ early this morning extended from west central TX,
northeast across KS and was transporting deeper gulf moisture
northward. Forecast soundings show a deep dry air layer above 800mb,
thus at this time the increasing isentropic lift on the 295 theta
level should not cause any thunderstorms due to the dry layer of air
and EML. I cannot rule out some light showers or drizzle developing
through the morning hours. By afternoon the stronger ascent ahead of
the upper trough will cool and moisten the mid levels of the
atmosphere. The elevated showers and thunderstorms should remain
elevated through most of the afternoon hours across the CWA. Several
of the higher resolution models show a break in the showers and
scattered thunderstorms during the mid and late afternoon hours.
Farther northwest of the CWA across northwest and west central KS a
dry line will push east from western KS and a surface cold front
will begin to push southeast into northwest KS. The NAM and WRF
solutions show the better instability developing in the afternoon
hours across west central KS. The most robust MLCAPE values of
around 400 j/kg will be centered from the Hill City, KS area
northward to the NE border. The vertical windshear will be strong
across west central KS with 0-6KM effective windshear of around 50
KTS. The low-level 0-1KM SRH will be between 200 and 300 j/kg. If
surface based storms can develop along the dryline and front
intersection across west central and northwest KS during the
afternoon hours they may evolve into low-top supercells. However the
instability is rather weak and the vertical windshear may inhibit
any deep moist convective updrafts from developing. Gradually the
instability axis of 200 to 300 J/KG will shift east into the western
counties of the CWA. If there are any isolated storm ongoing they
may move into the western counties during the early evening hours.
Though the tendency after sunset will be for these scattered surface
based storms to become elevated. I suppose with any low top
supercell there may be small hail, a possible severe wind gust and
perhaps a isolated weak tornado if any low top supercell can remain
surface based while entering into the western counties of the CWA
this evening. IMO, I think the storms will become elevated and will
only provide a chance for small hail and gusty winds while moving
into the western counties of the CWA after 00Z. The better chance
for any severe low top supercells will be west of the TOP CWA during
the afternoon hours. The WRF solutions show only a line of surface
based storms developing southwest of Hill City northeast into south
central NE, and these storms remaining northwest of the CWA during
the late afternoon and early evening hours. There may be some
elevated thunderstorms across most of the CWA but unless they become
surface based they will not be severe. Farther east across the CWA
the MLCAPE values drop off to less then 50 J/KG even though the low-
level shear remains strong with 400-500 J/KG of 0-1KM SRH.
As the H5 trough lifts northeast into the central high plains, a
lee surface low will deepen across eastern CO and western KS.
The tightest surface pressure gradient will develop across west
central KS during the early afternoon hours, and shift northeast into
south central NE. Sustained surface winds across north central KS
will increase to 25 to 30 MPH with gust to 40 MPH and continue into
the afternoon hours. The south central counties will see similar
winds developing through the afternoon hours. It looks as if the
cloud cover will hold through the afternoon, so I do not expect
dry adiabatic mixing to be much above 900mb. Therefore I don`t think
a wind advisory will be needed for the CWA Today. It will be windy,
especially southwest of a Emporia to Concordia line where wind
speeds may come close to having 30 MPH sustained winds with some
gusts of 40 to 45 MPH. Northeast and east central KS will see
southerly surface winds increase through the morning hours to 15 to
25 MPH with gusts of 35 MPH possible through the afternoon hours.
Overall, it will be a windy day across the CWA.
Cloud cover should keep highs in the mid and upper 50s. There may be
some lower 60 degree readings across the southwest counties of the
CWA.
Tonight, if a line of elevated storms develop they will move through
the CWA during the evening hours and should be southeast of the CWA
after midnight. Once again the best chance for a few strong storms
will be in the early evening hours across the western counties of
the CWA. Though the higher resolution models such as the WRF and RAP
keep the stronger surface based storms northwest of the CWA during
the afternoon and early evening hours. Once the lead H5 trough lifts
northeast of the CWA the 850mb winds will veer more to the southwest
and the western edge of deeper gulf moisture will translate east
into MO.
.LONG TERM...(Monday through Saturday)
Issued at 259 AM CST Sun Nov 27 2016
Another quiet weather period for the work week into next weekend
with no precipitation expected. The upper low system continues to
track north on Monday bringing slight WAA in the morning, and
neutral advection towards the afternoon. This leaves northeast
Kansas with warmer than normal temperatures once again Monday, with
highs in the upper 50s and low 60s. The system shifts east Tuesday
bringing northwest flow back to the area and moderating temperatures
back to near seasonal values. Wednesday onward, conditions remain
relatively similar with high temperatures in the mid 40s and lows in
the 20s. The next upper level system moves into the northwest US
Thursday morning; however, this system is progged to move south and
cut off from the mean flow leaving northeast Kansas in relatively
zonal flow beginning Friday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 546 AM CST Sun Nov 27 2016
Low level moisture continues to stream northward across the area.
Cigs are expected to continue lowering through the morning with
IFR prevailing by 15Z at all terminals. Southerly winds will
increase by 15Z as well with sustained 15-20 knots and gusts
approaching 30-35 knots. Scattered showers will develop across
portions of central KS later this morning and drift eastward,
therefore have VCSH introduced at MHK by 15Z and 17Z for TOP/FOE.
A secondary round of t-storms are expected to arrive early this
afternoon. All shower/storms will exit the area by 00-01Z
timeframe, improving cigs to MVFR. VFR conditions will return by
02-05Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...Heller
AVIATION...Baerg
Area Forecast Discussion
National Weather Service Duluth MN
404 PM CST Sun Nov 27 2016
.SHORT TERM...(This evening through Monday)
Issued at 403 PM CST Sun Nov 27 2016
Fog and clouds have been the main concern in the very short term
this afternoon and evening. We have warm moist air being advected
into the area over the top of our existing snow, and it is causing
the fog and low clouds over large portions of the forecast area.
Places with less snow have had a greater increase in visibility this
afternoon, so you can see almost exactly where our heavy snow band
was just over a week ago. I expect cooling temperatures to cause
the visibilities to lower once again this evening, but perhaps not
quite as low as they were before with the higher cloud coming to
help dampen the cooling trend. I have cancelled some counties out
of the advisory this afternoon based on latest trends, but I may
have overdone it if the cloud cover isn`t quite thick enough and
advisory may need to be expanded again.
This is all in advance of the storm system that has been
developing out over the plains all day, with a strong upper low
over western Nebraska this afternoon and the surface low is
developing nicely over the CO/NE/KS corner area. The upper low
becomes slowly cut off as it moves northeast into South Dakota by
overnight tonight, with a surface low deepening and moving to
eastern South Dakota. The strong wave of warm moist advection,
isentropic lift and frontogenesis moves across the area overnight
tonight bringing a wave of precipitation across the forecast area.
Have kept pops in this band very high overnight. Monday the entire
system becomes stalled over eastern North Dakota and northwest
Minnesota as the upper low gets even more cut off, and it wraps
some dry air around the southern side and into our southeastern
counties during the daytime. Have kept pops fairly high closer to
the upper low, but with the dry air wrapping in have lowered pops
over my northwest WI counties. This also brings some instability
into my southeast, and have included some potential for thunder
during the day as well. Precipitation on Monday will be pretty
showery in nature with the instability nearby. Dry slotting may
keep the east almost dry tomorrow. Temperatures to be nearly
steady overnight tonight with the warm air advection going on, but
should rise in the warm sector tomorrow for even more melting in
the rain.
.LONG TERM...(Monday night through Sunday)
Issued at 403 PM CST Sun Nov 27 2016
The upper level low pressure system will essentially park itself
over the Minnesota and Wisconsin area from Monday night through
Wednesday, before finally pulling off to the east for the end of
the work week. The presence of the upper low and resultant
associated moisture will result in a prolonged period of
precipitation for nearly all of the work week. While most of the
daytime precipitation looks to be in the form of rain, we could
see a transition to some light snow, especially at night. Overall,
it will be a mild start to the week, but temperatures are
gradually expected to settle into more normal readings for the
middle to end of the work week. The highest POP`s will be during
the first part of the week, with the system maintaining the most
moisture at the onset of the development of the closed low. As the
week wears on, we should see POP`s drop into the chance range, and
then essentially dry out by Friday. High temperatures will range
from the mid 30s to lower 40s early in the week, and then
gradually drop into the upper 20s to middle 30s as the week wears
on.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1151 AM CST Sun Nov 27 2016
Another tough forecast for the Northland TAF sites this afternoon,
with widespread dense fog hanging tough in many areas. A hole in
the clouds had developed across northwest Wisconsin, with clear
skies at KHYR as of 18Z. There was also some modest improvement at
KBRD and KINL, with VLIFR at KDLH and KHIB. The big question is
how much improvement there will be for the remainder of the
afternoon. The HRRR indicates we may not see much, if any
improvement, especially at KDLH, with persistent east flow. KDYT
only has a CIG of 300 feet, and that would indicate we would have
a tough time of seeing much improvement. HRRR maintains 1/4 mile
VSBY at KDLH into the night, before incoming rain starts to
improve VSBY`s across much of the area. To make a long story
short, we will maintain VLIFR at KDLH and try to bring some
improvement elsewhere. With rain moving rapidly in from the south
and west tonight, we will continue to see low clouds, but probably
see some improvement in VSBY. Since there is no airmass change
through the TAF period, once the rain lets up, we will probably go
right back down in fog. East winds will increase markedly through
the night, especially at KDLH. We may also see a few thunderstorms
on Monday, especially by afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 34 44 36 39 / 100 60 60 30
INL 31 42 36 40 / 90 80 60 60
BRD 35 45 33 39 / 100 50 40 40
HYR 36 45 35 40 / 100 50 50 30
ASX 35 47 39 43 / 100 50 50 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Dense Fog Advisory until 9 PM CST this evening for MNZ025-
033>037.
Dense Fog Advisory until midnight CST tonight for MNZ012-018>021-
026.
LS...Small Craft Advisory until 4 AM CST Tuesday for LSZ121-146>148.
Small Craft Advisory until 4 AM CST Tuesday for LSZ142>145.
Small Craft Advisory until 1 AM CST Monday for LSZ140-141.
Small Craft Advisory from 7 AM Monday to noon CST Tuesday for
LSZ140-141.
Gale Warning from 1 AM to 7 AM CST Monday for LSZ140-141.
&&
$$
SHORT TERM...LE
LONG TERM...DAP
AVIATION...DAP
Area Forecast Discussion
National Weather Service Hastings NE
319 PM CST Sun Nov 27 2016
.SHORT TERM...(This evening through Monday)
Issued at 318 PM CST Sun Nov 27 2016
Current radar has showers and maybe an isolated thunderstorm moving
through the central to northeast part of the forecast area.
Satellite shows clearing in or near the southwest portion of the
area this afternoon. Surface analysis still has the low pressure
system near the Nebraska/Kansas/Colorado borders.
The main question for the remainder of the afternoon and into the
evening is if there will be enough instability near the clearing
line to start a few thunderstorms. The HRRR has been consistent with
having some convection that starts in the north central Kansas
counties and moves to the northeast from there. There is also a
small area that starts up in the west before moving to the
northeast. The best timing for the thunderstorms will be from about
3pm to 6pm. There is still a question as to how much instability
there will be. The RAP brings a small area of 500 to 1000 j/kg into
the southwest and pushes it across as it weakens. Once the sun goes
down this evening, that should effectively cut off chances for
thunder.
The precipitation should move off to the northeast of the forecast
area during the evening hours and there should be some clearing
behind the precipitation. As the surface low moves to the
east/northeast into this evening. The winds should turn to the west
and bring in drier air to the area during the evening hours. The
clearing skies and drier air should allow temperatures to fall off
into the mid 30s.
A little wrap around moisture will bring some clouds back to the
area for a time on Monday, but the clouds will move out during the
afternoon. Temperatures will warm back into the lower 50s during the
afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 318 PM CST Sun Nov 27 2016
There will be mostly northwest flow across the area through this
period. There are a few waves that move through the area. Have kept
the forecast dry through the period, but each of the waves brings an
increase in cloud cover and a weak cold front. The first wave moves
through Monday night. Temperatures will be cooler Tuesday and there
will be a few more clouds around. Temperatures will remain cooler
than normal with in and out clouds Wednesday through Friday. A
surface high moves through the area on Friday and when it moves to
the southeast Friday night, winds will turn back to the south and
temperatures will start a slow increase back to near normal for the
weekend.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening)
Issued at 318 PM CST Sun Nov 27 2016
Showers and maybe a few isolated thunderstorms will move through
the terminals this afternoon. Lower clouds should gradually give
way to higher clouds as the surface low moves to the northeast.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...JCB
Area Forecast Discussion...CORRECTED
National Weather Service Jacksonville FL
129 PM EST Sun Nov 27 2016
.NEAR TERM Through Monday...
Surface high pressure north of the area will move eastward
tonight and Monday. Northeast flow over our area today will become
more southeasterly Monday. Anticipating some high clouds from NW
this afternoon and tonight with greater coverage over GA...and
some lower clouds over coastal waters that could move over our
coastal counties. Not anticipating any precip through tonight.
Latest consensus guidance supports current low temp forecast
tonight of upr 40s sctrl GA to mid 50s nctrl FL with upr 50s
coast. Uncertainty on patchy fog tonight...conditions may be more
conducive to dew and patchy shallow groundfog...so leaving fog out
of forecast for tonight. Latest HRRR seems to support this with
just patchy fog shown over nctrl FL GNV-OCF.
Partly cloudy skies expected Monday. Guidance conflicted on
potential for any showers over forecast area with NAM more
aggressive than GFS...even less potential on ECM (only showers
over coastal waters). Will only go very low POPs for eastern
counties and coastal waters for Monday. Warmer temps Monday with
highs generally mid-upr 70s.
.SHORT TERM...Mon night through Wed night...
Mon Night...Low chance of an evening shower across inland areas
as a weak pre-frontal warm front lifts northward up the Fl
peninsula and interacts with weak sea breeze convergence and
diurnal heating. Otherwise mostly dry conditions with warm low
temperatures about 10-15 deg above climo values ranging in the
low/mid 60s. Boundary winds appear too strong for significant fog
formation but could have some low stratus move across the area
from the Gulf towards sunrise as well as areas of fog with some
patchy intermittent dense fog.
Tue through Wed night...Near record warmth both days with strong
warm air advection pattern across the area ahead of long wave
trough and surface cold front. High temperatures will rise into
the low to possibly mid 80s across our southern FL zones under
breezy southerly winds of 15-20 mph with gusts to 30 mph at times.
Mostly dry conditions will prevail through Wed afternoon...but
there will be a low chance (< 20%) of a diurnally enhanced shower
along the sea breezes and/or weak warm front axes rotating
northward ahead of the trough from south Florida. Rain chances
increase Wed night especially after midnight across our inland GA
zones and the Suwannee River Valley with the as the surface cold
front finally begins push farther east. Will continue with mention
of isolated tstorms and showers along the front Wed night and Thu
with pre-frontal precip likely breaking apart as it crosses our
local area as stronger upper level dynamics lift NE of the area
and best low level instability hugs the Gulf Coast region and over
the adjacent Atlantic waters. Main convective concern will be
gusty winds. The 00Z ECMWF trended drier than recent runs with now
storm total amounts generally only a tenth of an inch or less
across much of the area...with the exception across our western
zones where up to a quarter to half inch may occur before stronger
dynamics and moisture fetch off of the Gulf become unphased. The
GFS20 continued to reflect little QPF while the official Weather
Predication Guidance indicated around a tenth of an inch or less
across much of NE FL to up to a quarter to half an inch across
portions of the Suwannee River Valley and parts of inland SE Ga.
.LONG TERM...Thu through Sun...
Surface cold front will push southward across the local area Thu
with precipitation ending and clouds gradually clearing into Thu
afternoon and evening as a dry and cooler NNW flow funnels in the
fronts wake as high pressure builds over the Gulf Coast states.
Temperatures will trend below climo values through next weekend
with dry conditions expected as the low level ridge dominates NNW
of the local area. Upper level flow will become near zonal with
waves of high clouds traversing the area downstream of a
developing low pressure system in the western Gulf of Mexico late
next week. Sun this low will begin to edge farther east which will
lift a warm front up the Fl peninsula with the potential for a
light isentropic rainfall event across some portion of our
forecast area early next week.
High temperatures will range in the 60s for much of this period
trailing the cold front Thu with some moderation into the low 70s
across portions of NE Florida late next week as flow becomes more
NNE ahead of lifting warm front. Low temperatures will range
generally in the 40s inland to 50s coast with the coldest night
still Fri night with lows falling into the upper 30s at some of
normally cooler inland locales.
&&
.AVIATION...
VFR conditions next 24 hrs with occasionally gusty northeast
winds. Lighter winds tonight...uncertain if fog will develop or
just dew and shallow ground fog late tonight...so left fog out of
TAFs for now...though best chance of any late night fog may be at
KVQQ and KGNV.
&&
.MARINE....
As high pressure moves east of mid-atlantic coast...winds over
our coastal waters should shift from northeasterly today to more
southeasterly Monday...and southerly Tue/Wed before shifting to
northwesterly Thursday as a cold front moves across the waters.
Will maintain exercise caution for coastal waters...but could see
periods of advisory winds during the week over the offshore
component...20-60 nm offshore.
RIP CURRENTS...Elevated risk through Monday with moderate onshore
flow.
&&
.FIRE WEATHER...
Elevated dispersions expected across portions of inland NE Fl
Monday afternoon and area wide Tuesday afternoon due to
very warm temperatures and breezy south winds. Humidity
will remain above critical values.
&&
.CLIMATE...
Near record warmth is expected Tue and Wed this week. Climate
data below.
SiteTue (Nov 29)Wed (Nov 30)
Record Max TempsRecord Max Temps
JAX85 in 197884 in 2010
GNV88 in 197886 in 1978
AMG81 in 200684 in 2006
SSI80 in 198581 in 1985
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 47 75 61 82 / 0 10 10 20
SSI 55 72 64 79 / 0 20 20 10
JAX 54 77 63 83 / 10 20 20 10
SGJ 59 76 66 83 / 10 20 20 20
GNV 53 78 61 83 / 10 10 20 20
OCF 55 78 61 83 / 0 10 20 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Wolf/Enyedi/Guillet
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
327 PM CST Sun Nov 27 2016
.SHORT TERM...(This evening through Monday)
Issued at 327 PM CST Sun Nov 27 2016
Water vapor imagery this afternoon shows a powerful shortwave
working across Kansas. Ahead of this pv feature and associated dry
slot, a band of showers and thunderstorms has developed across
eastern Nebraska and western Iowa and this area is moving off to the
northeast toward SW MN at about 40 kts. High res models in really
good agreement on timing this initial band of rain in and through
the area and followed a blend of them to bring in the band of 100
PoPs from south to north across the area. Pretty much everything is
also in agreement on precip amounts with this rain coming in between
0.3" and 0.5" across the area.
Tonight, the dry slot over western KS will move into southern MN.
This will likely cut off the precipitation across the entire area by
the start of the day Monday, with redevelopment of showers/storms
expected along an occluded front late Monday morning into the
afternoon. In all likelihood, we probably have PoPs lingering too
long tonight/tomorrow morning, but differences among the hi-res and
deterministic models in the placement of the dry slot has us
likely bleeding a little too much PoP into Monday morning. For the
Monday afternoon activity, with the surface low nearby, ample
shear exists for a severe threat, but there is virtually no
surface based instability, which pretty much ends any severe
threat right there, but certainly this setup in say May would
probably be quite interesting.
For temperatures, beside rain, very warm temperatures are surging
north out of Nebraska and Iowa we should continue to see our
temperatures rise through the night. For most, highs for the
calendar day will be achieved right at 1159 pm. East of the
occluded boundary it will be very mild Monday, with highs in the 50
to 55 range likely. The record high for MSP Monday is 58. To achieve
this, it would need to be a cloud free dry slot and even then, 58 is
probably a little out of reach. However, those highs in the 50s for
eastern MN into western WI will be in the ballpark of 20 degrees
above normal.
.LONG TERM...(Monday night through Sunday)
Issued at 327 PM CST Sun Nov 27 2016
Much of the week will feature considerable cloudiness and
occasional light rain and/or snow showers as an upper low slowly
moves east across Minnesota and Wisconsin early to mid week. The
best chances for precip will be over western MN closest to the
upper low Monday night into early Wednesday until the wrap around
precip finally reaches Wisconsin Wednesday afternoon and the dry
slot heads east.
Temperatures will be fairly mild ahead and under the upper low
with diurnal spreads of only 2 to 5 degrees. Most of the precip
will be in the form of rain and thus snow accumulations are
expected to be meager and confined to near the SODAK border where
maybe an inch or two will fall through Wednesday.
A ridge will finally move in Friday with dry weather expected into
the weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1159 AM CST Sun Nov 27 2016
One of the more impressive dense fog events you are ever going to
see up here is finally start to improve as increasing SE winds
slowly bring better visibilities up from the southeast. A couple
of numbers that stick out from this fog were minimum RVRs this
morning at MSP of just 600-800 ft, but most staggering of all is
what has happened at AXN. AXN has been at 1/4sm or less since 17z
yesterday and will likely spend over 30 hours in dense fog. For
improvements, the HRRR vis forecast has been pretty good today, so
followed it for timing improvements in vis. For AXN, this
basically means its more 1/4sm vis until the rain arrives this
evening. As for the rain, short term models are in good agreement
on when it gets here and only needed to delay the onset in TAFs by
about an hour. Confidence in the forecast diminishes considerably
behind this band of rain as a dry slot works into the area. The
HRRR has clear skies coming into southern MN late tonight, so
tried to hint at some better conditions being possible at RWF and
MSP as the dry slot comes in. For AXN, there is a good chance
they descend back into dense fog behind the rain shield as they
will be closer to the surface low with deeper moisture and less
mixing.
KMSP...We are finally getting out from under the fog and we are
done with it the rest of the TAF period. We`ll get a brief period
of VFR clouds, but MVFR cigs are already up to Ames, IA.
Confidence is high in rain moving in between 1z and 2z. We`ll see
continuous rain until 6z, but at that point MSP will start getting
into the influence of the dry slot and confidence in the TAF
decreases considerably at this point.
/OUTLOOK FOR KMSP/
Tue...MVFR/IFR. Chc -RA. Wind SW 5-10 kts.
Wed...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.
Thu...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Dense Fog Advisory until 6 PM CST this evening for MNZ041>043-
047>050.
&&
$$
SHORT TERM...MPG
LONG TERM...BORGHOFF
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
406 PM EST Sun Nov 27 2016
.SHORT TERM...(This evening through Monday)
Issued at 356 PM EST SUN NOV 27 2016
WV imagery and RAP analysis indicated a mid/upper level trough over
much of the wrn CONUS, from the Rockies into the wrn plains. A
vigorous lead shortwave was lifting northeast into wrn IA. At the
surface, se winds were increasing between a 989 mb low over sw
Nebraska and a ridge from Quebec into the ern Great Lakes. With
daytime warming, low level moisture trapped below a 1k-2k ft
inversion has lifted to a low stratus deck over most of the cwa
except over portions of the west where downslope se flow was
strongest.
The short range models were in good agreement with the
progression/onset of the rain ahead of the IA shrtwv and surge of
295k-305k isentropic lift. Expect the rain developing from sw to ne
between 06z-12z to taper off during the morning after the initial
band moves through. Although the mid level moisture will depart
during the day, continued low level isentropic lift will maintain
some light rain or drizzle through most of the day, with lower
amounts and coverage near Lake Superior where the strongest
downslope wind prevails. Fog may thicken again tonight with the loss
of sfc heating but with the rain moving in, should not be as dense
into Monday as it was this morning. Temps will remain steady or
slowly rise tonight and then climb just a few degrees to the lower
to mid 40s Monday.
.LONG TERM...(Monday night through Sunday)
Issued at 405 PM EST SUN NOV 27 2016
Positive height anomalies currently dominating much of the east half
of Canada will expand across most of Canada by midweek, then
diminish in magnitude/coverage next weekend. To the s, energy
flowing off the ne Pacific will carve out the long advertised
central CONUS trof over the next few days. This trof will then
evolve to a positive tilt from se Canada/New England to the sw CONUS
by late week. Next weekend, lower amplitude flow looks to develop
briefly across the northern CONUS/southern Canada prior to trof
development in the vcnty of far western N America in the 8-10day
period. This trof development will herald a potential pattern change
across N America heading into mid Dec that will initially lead to
advection/build up of arctic air into western Canada. Ahead of the
developing central CONUS trof in the shorter term, southerly flow
will push temps well above normal across the area over the next
couple of days. While temps will fall back closer to normal later in
the week as the trof axis drifts e, readings should remain a little
above normal as the positive height anomalies across Canada prevent
any arctic air from developing or dropping s thru Canada and into
the CONUS. As for pcpn over the next 7 days, the developing central
CONUS trof will bring a wet period into early Tue with all of the
pcpn in the form of rain. Pcpn will then transition to ocnl lighter
snow mid and late week with troffing over the area, though there
will be potential of lake enhanced snow that may provide some
accumulations. Looking farther ahead beyond this 7 day fcst,
CPC/NAEFS outlooks in the 8-14 day period, out to Dec 11, now show
diminishing probabilities of above normal temps as the start of the
potential pattern change moves into that time period. Farther out,
CFSv2 runs continue to show the pattern change toward colder weather
heading into mid Dec as positive height anomalies that have
dominated Canada for many weeks give way to negative height
anomalies. The changes shown are consistent with GFS/ECMWF trends
for early next week which show western N America trof development
initially which leads to advection/build up of arctic air in western
Canada. Could be an active period of weather as this cold air shifts
farther e and se. However, it is noted that the majority of Canadian
ensembles valid Dec 13 have a mild look for the Upper Lakes.
Beginning Mon night/Tue, the second of 3 significant pieces of
energy moving thru the central CONUS trof will lift into the Great
Lakes. This second wave will have stronger jet dynamics/upper
diffluence and stronger deep layer forcing compared to the first
wave that generates pcpn tonight/Mon. Result will be heavier
rainfall affecting the fcst area Mon night into early Tue morning,
especially across the central and eastern fcst area. Potential is
there for 1+ inch of rainfall over roughly the e half where stronger
forcing better overlaps warm conveyor belt deep moisture ribbon
which has precipitable water around 0.80 inches/250pct of normal.
Passage of occluded front to the n and ne Tue morning will then
bring an end to the steadier/heavier rain. Models have been trending
more toward a dry period following fropa under mid level drying.
Fcst will follow suit, but will retain a schc mention over the far w
Tue aftn, closer to mid level low center over MN. Expect low temps
Mon night in the upper 30s/lwr 40s. High temps on Tue may reach 50F
over the e, especially if clouds break, while low/mid 40s will be
the rule w.
It now appears that the 3rd piece of significant energy moving thru
the central CONUS trof will probably have a track far enough w to
spread deep layer forcing and deep moisture back into Upper MI on
Wed, especially across the e. Given multi-model trends, fcst will
show chc pops spreading across the e and much of the central fcst
area on Wed. Wetbulb zero heights support only rain as ptype. Over
the far w, deep moisture in the vcnty of the decaying mid level low
may support some -shra, perhaps mixed with snow.
Thu into Fri, fcst area will be under the influence of the gradually
weakening mid/upper level trof that will extend from se Canada to
the sw CONUS at the end of the week and the associated sfc trof.
With deep moisture and 850mb temps gradually falling to -5 to
-8C, expect some -shsn/-shra transitioning to mainly -shsn across
the area. There is the potential of lake enhanced snow off Lake
Superior, dependent on location/movement of the sfc trof across the
Upper Lakes. ECMWF is much sharper with this trof, offering
potentially mdt snow accumulations in the Lake Superior snow belts
Wed night/Thu. Not a lot of consistency run-to-run and btwn models
with the details, but this will be a time period to monitor for some
snow accumulations in the Lake Superior snow belts, especially
across the higher terrain of western Upper MI and then e toward
Marquette. Light LES will then continue into Fri.
Model trends are quicker toward a transition to a lower amplitude
more zonally oriented flow over the weekend. There will likely be a
shortwave passing during this transition period, but any pcpn that
might occur should be light.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 108 PM EST SUN NOV 27 2016
abundant low level moisture below a sharp 1k-2k ft has kept the low
cigs and patchy dense fog going into this afternoon at SAW and CMX.
With continued low level se flow, any improvement will be limited
this afternoon before diurnal cooling and additional moisture
advection brings additional support for low cigs and dense fog. The
upslope flow at CMX will also help sustain the dense fog. Although
doownslope flow at IWD has brought VFR conditions, expect cigs to
drop to MVFR this evening. Rain spreading across the area late
tonight into Monday morning may help scour out some of the fog but
will still support low cigs.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 356 PM EST SUN NOV 27 2016
High pressure over the ern Great Lakes will shift to the east
tonight as low pressure deepens across the northern plains into the
upper midwest. This will result in a tight pressure gradient
developing across the northern Great Lakes creating gales overnight.
Gales to 40kt are expected across all of Lake Superior spreading
west to east, but the gradient will slacken earliest across the far
west. Further east the gradient will remain tight, with gales
lingering through Mon night. The low pressure system will linger
over the upper midwest Tuesday into Wednesday. However the pressure
gradient is not expected to be as tight and allow winds to diminish
below 25kt by Tuesday evening. Northerly winds to around 25 knots may
develop Thursday as the slow moving low moves to the east of Lake
Superior into Quebec.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from midnight tonight to 10 AM EST Tuesday for
LSZ249>251-266-267.
Gale Warning from midnight EST /11 PM CST/ tonight to 10 AM EST
/9 AM CST/ Monday for LSZ162.
Gale Warning from midnight tonight to 4 AM EST Tuesday for
LSZ243-244-264.
Gale Warning from midnight EST /11 PM CST/ tonight to midnight
EST /11 PM CST/ Monday night for LSZ240>242-245>248-263-265.
Lake Michigan...
Gale Warning from 4 AM Monday to 4 AM EST Tuesday for LMZ221-248-
250.
&&
$$
SHORT TERM...JLB
LONG TERM...Rolfson
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Morristown TN
334 PM EST Sun Nov 27 2016
.SHORT TERM (This Afternoon through Monday)...
High clouds are already moving in across the forecast area ahead of
the approaching system. Current water vapor imagery and RAP upper
air analysis indicates a couple of shortwave troughs, one located
across the Rocky Mountains and another moving along the Pacific
Coast. Upper level ridging extends from the Gulf of Mexico
northwards into the Great Lakes. At the surface, high pressure is
centered just to the east of the area across the Carolinas with lee
cyclogenesis along the front-range of the Rocky Mountains. Dry
conditions have continued this afternoon with dewpoints in the
upper teen to low 30s has lead to enhanced fire danger across the
area this afternoon and issued a statement earlier this morning.
Cloud cover will continue to increase overnight as the upper level
trough dives quickly into the Southern Plains. The surface high
will shift eastward out over the Atlantic with southerly flow
returning to the area. This southerly flow will advect moisture
into the area ahead of the approaching cold front. Overall, expect
the bulk of the moisture will arrive just beyond the end of the
short-term period. A few shower will be possible along the highest
elevations where a bit of upslope may occur Monday and again
across the Plateau as the system starts to move in late in the
forecast period. The main impact in the short-term period will be
the strong southerly winds that develop ahead of the system. The
GFS is the strongest with the low level winds indicating 925 mb
winds of 50-60 kts late Monday night. The NAM and ECMWF are a bit
more conservative in the 35-45 kt range. Regardless, strong
southerly winds are forecast ahead of the system. With this, a high
wind watch continues for the higher elevations in SW NC and along
the TN/NC line. Wind speeds of up to 60 mph will be possible in
the higher elevations. A wind advisory has been issued for the
remainder of E TN where winds will gust to around 40-45 mph at
times late Monday.
.LONG TERM (Monday night through Sunday)...
Monday night: Period starts with precip knocking on our door with
longwave trough just to the west. Latest guidance continues to
suggest best chance of pops will be around midnight and through
early Tuesday morning. Initially, have pops increasing from the west
but did define an area of much lower pops along the foothills of our
eastern mountains to account for strong downward vertical motions.
Downsloping winds will keep this area the driest the longest, but it
will eventually rain. 60 to 70kt jet moving in overnight has
prompted a high wind watch for the higher elevations of our eastern
mountains and a wind advisory elsewhere, expect for our Southwest
Virginia counties. An advisory for our Virginia counties will likely
come during the next forecast issuance. Winds could gust over 60 mph
across the highest elevations with gusts up to 40 across lower
elevations. Still looking at generally three quarters of an inch to
one and half inches of precip Monday night into Tuesday morning
south of I-40. Half an inch to three quarters of an inch for
Northeast TN and Southwest Virginia. PW values continue to be near
max values for this time of year. Lows Monday night will be mild
with lows 15 to 18 degrees above normal. Lows will only be a few
degrees below our normal highs for this time of year.
Tuesday: NAM in a little better agreement today with GFS and ECMWF,
but still not great. NAM still wanting to hang up the boundary
across the eastern mountains and allow precip to hang in east of I-
40, especially across the foothills and eastward, for much longer
Tuesday than other models. Will continue to split the difference in
pops. Currently have high wind watch and advisory expiring 12z
Tuesday as the stronger jet core move east of the mountains. Tuesday
still looks breezy though as there is still a 30 to 40kt 850mb jet
in place through the day. Highs on Tuesday in the upper 60s to low
70s due to strong southwest flow and partial clearing later in the
day. Last half of Tuesday into first half of Tuesday night looks dry.
Tuesday night and Wednesday: Dry conditions will quickly give way to
another large batch of precip moving in as another wave of moisture
surges in from the southwest. PW values with this wave are at record
levels as soundings are completely saturated from the surface all
the way up through the upper levels of the atmosphere. Highest pops
look like they will occur after midnight and continue through much
of Wednesday. During this time we could pick up 1 to 3 inches of
rain across much of our area, with 1 to 2 inches across Northeast
into Southwest Virginia. It also appears that we could see some
strong storms late Tuesday night and into Wednesday morning across
the Southern TN Valley. Soundings indicate robust shear in place
with low to moderate CAPE values for this time of year. The main
threat with any storms at this time appears to be small hail and
damaging winds. Lows overnight will be near our normal highs. Highs
on Wednesday will be in the low to mid 60s. Event total precip still
looks like a general 2 to 4 inches of rain for most of the area with
1 to 3 inches for Northeast TN into Southwest Virginia. Locally
higher amounts possible across the Central and Southern TN valley.
Wednesday night and beyond: A few light showers could linger
overnight and into Thursday morning but the bulk of the precip will
have moved off to our east. Lows will be cooler behind the boundary
with temps in the upper 30s to low 40s. A more zonal flow returns
Thursday and lasts through the remainder of the long term giving us
quiet weather. Highs and lows during this time will be more
seasonable. Another system looks to move in at the end of the period
that could bring us more rain.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 44 67 55 73 / 0 30 100 60
Knoxville McGhee Tyson Airport, TN 39 65 55 72 / 0 10 100 70
Oak Ridge, TN 40 62 53 71 / 0 20 100 60
Tri Cities Airport, TN 31 60 49 69 / 0 10 90 80
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...High Wind Watch from Monday afternoon through Tuesday morning
for Cherokee-Clay.
TN...High Wind Watch from Monday afternoon through Tuesday morning
for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-
Northwest Carter-Sevier Smoky Mountains-Southeast Carter-
Southeast Greene-Southeast Monroe-Unicoi.
Wind Advisory from 1 PM EST /noon CST/ Monday to 7 AM EST /6 AM
CST/ Tuesday for Anderson-Bledsoe-Bradley-Campbell-
Claiborne-East Polk-Grainger-Hamblen-Hamilton-Hancock-
Hawkins-Jefferson-Knox-Loudon-Marion-McMinn-Meigs-Morgan-NW
Blount-North Sevier-Northwest Cocke-Northwest Greene-
Northwest Monroe-Rhea-Roane-Scott TN-Sequatchie-Sullivan-
Union-Washington TN-West Polk.
VA...None.
&&
$$
MA/SR