Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/12/17
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
808 PM MST Sat Mar 11 2017
.UPDATE...
Peak east winds ongoing below gaps in the central mt chain with gusts
up to 50 mph in a few areas. Speeds expected to drop off in the next
hour or two below advisory levels. Updated for lower temps across a
good chunk of eastern NM where readings already in the 30s. Added
more low cloud cover and patchy fog to the mix with drizzle over the
east central and southeast plains as well.
Guyer
&&
.PREV DISCUSSION...507 PM MST Sat Mar 11 2017...
.AVIATION...
00Z TAF CYCLE
Aviation impacts to focus around KABQ with a burst of strong gap
winds this evening. Airport weather warning in effect for east wind
gusts near 40kt thru 05Z. The other area will be around KROW with
MVFR/IFR cigs & vsbys from low clouds and fog overnight. An area of
low cigs between 010 and 015 may impact KTCC and KLVS with lower
confidence. Will include in next issuance is model trends continue.
Conditions to clear Sunday and winds will turn back around to the
south/southwest by late morning.
Guyer
&&
.PREV DISCUSSION...336 PM MST Sat Mar 11 2017...
.SYNOPSIS...
Cooler air from the back door front will continue across the eastern
plains before seeping into the Rio Grande Valley tonight. Anticipate
gusty east canyon winds around sunset as the front squeezes through
the gaps of the central mountains. The front will also help develop
isolated thunderstorm chances across the extreme SE Plains
tonight...but greater chances south of coverage area. Temperatures
across the eastern plains will take on a yo-yo affect the next
couple of days because of a series of back door cold fronts
through midweek...but the dry and unseasonably warm pattern will
prevail for the next several days.
&&
.DISCUSSION...
Some isolated showers and thunderstorms have already begun
developing across portions of the extreme SE Plains ahead of the
incoming back door front that`s currently pushing across the eastern
plains. Current LAPS models is showing -5 and -6 lifted indices with
sfc based CAPE ranging from 1000-1400 J/Kg over central Chaves and
Roosevelt counties. However, the latest HRRR models showed most of
the anticipated activity south of our CWA with minimal
precipitation chances over Chaves or Roosevelt counties. Isolated
activity is still imminent to develop as the back door cold front
reaches moist prone areas but any severe possibilities will be
south of our CWA. Also lowered PoPs across the Sangre de Cristos
because of recent models trending drier across the area.
Meanwhile, gusty winds will follow the front as it travels south and
west tonight. East canyon winds will impact the RGV around sunset
before tapering off Sunday morning. As the front pushes west of
the central mountain chain, some moisture will follow but looks to
quickly dry out Sunday afternoon as front washes out and drier NE
flow aloft filters in. Temperatures will rebound several degrees
across the east Sunday with cooler temperatures elsewhere but
another shallow back door cold front will impact areas east of the
central mountain chain late Sunday night into Monday
morning...again lowering temperatures across the NE Plains. The
front will wash out Monday afternoon allowing values to slowly
rebound...also following an upper level ridge building over the
Desert SW into Tuesday.
Wednesday through the following weekend looks to be warm and fairly
dry as the center of the upper level ridge inches closer to the
state. Above normal temperatures will also prevail the rest of the
forecast week with possible record/near record highs in the
eastern plains toward the end of the week.
32
&&
.FIRE WEATHER...
another backdoor cold front is pushing down the Eastern Plains and
will progress west overnight through the Central Mountain and out to
near the Arizona border. Humidity recovery behind the front will be
excellent east and generally fair to good west.
Look for some drying Sunday as the airmass mixes-out for the most
part. Elevated fire weather conditions are forecast Sunday afternoon
across the Northeast Plains thanks in part to warming from downslope
winds. Another backdoor front will push down the Eastern Plains
Sunday night into Monday providing come cooling/moistening, but
highs are still forecast to reach above normal most areas behind the
front. Across western New Mexico, above normal temperatures and dry
conditions will persist.
A warming/drying trend is forecast Tuesday through Thursday as a
ridge pumps up and shifts east over the area. Temperatures will
generally be well above normal and Haines Indices will be on the
uptrend. Elevated fire weather conditions are likely Thursday across
the northeast quarter of the state as the ridge crashes and
afternoon breezes materialize.
After a brief pause in the warming trend thanks to a backdoor front
Thursday night into Friday, warming will continue into the weekend
as a large ridge of high pressure builds over northern Mexico and
southern New Mexico with good agreement between the 12z ECMWF and
GFS operational solutions.
11
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Wichita KS
533 PM CST Sat Mar 11 2017
.SHORT TERM...(This evening through Tuesday night)
Issued at 312 PM CST Sat Mar 11 2017
A narrow, west to east oriented band of snow extending from central
Kansas to central Missouri this afternoon, will continue to slide
slowly southward across southern Kansas through early evening before
exiting to the south. This band of snow appears tied to 650-600 mb
layer frontogenesis, associated with a shortwave trough. Latest runs
of the Rap and especially Nam-wrf maintain this frontogenetic
forcing longer than prior runs, therefore think it should maintain
itself before exiting our southern-most counties by around 02 UTC
this evening. The snow band may become mixed with rain further south
with temperatures more marginal. If the snow band maintains itself,
a dusting up to a 1/2 inch of accumulation can be expected.
Strong subsidence is progged in the wake of this departing wave
overnight, although considerable low cloud cover could linger across
much of the area with the subsidence occurring above a low-level
temperature inversion.
A more vigorous shortwave trough along the Pacific Northwest Coast,
(readily apparent via GOES-R water vapor channel), is progged to
dive southeast across the Central Plains Sunday night into Monday
morning. Ahead of this wave, lee troughing will allow for gusty
southerly winds during the day Sunday. Strong dynamics but meager
moisture return will result in scattered light rain showers as the
upper trough and cold front move through Sunday night. Cooler air
will spread into the region behind this system for Monday-Tuesday,
with gusty northerly winds of 15-25 mph Monday morning into early
afternoon.
.LONG TERM...(Wednesday through Saturday)
Issued at 312 PM CST Sat Mar 11 2017
A deep mid-upper level cyclone will encompass the northeastern
states to begin this extended forecast period, with broad upper
ridging over the Intermountain Region, and an upstream upper trough
over the northeastern Pacific. This will keep slightly cooler than
average temperatures from lower elevations of the Central Plains
eastward on Wednesday. The GFS and ECMWF deterministic runs continue
to hint at light precipitation potential in the northwest flow aloft
Wednesday, tied to mid-level forcing, but keep having run to run
oscillations on placement/timing. Thinking any chance for light
rain/snow in our forecast area is slight at best this far out.
The upper cyclone over the northeast is progged to lift gradually
northeastward while weakening toward the end of the week. Meanwhile,
a shortwave trough is progged to eject from the northeast Pacific
upper trough, eastward across the northern/central Plains sometime
Thursday night into Friday, although the 12z GFS was significantly
faster than the ECMWF with this feature and it`s attendant Pacific
cold front. The GEFS ensembles begin to show increased spread in the
500 mb pattern late in the week, mainly with respect to the
departing upper cyclone in the northeast. Although uncertainty
exists with the frontal timing, marginal gulf moisture return and at
least elevated instability, should result in at least low
probabilities for showers/thunderstorms sometime Thursday night
through Friday. Confidence is above average that temperatures will
climb above seasonal averages for late in the week, but lesser on
precipitation chances/timing.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 532 PM CST Sat Mar 11 2017
Challenging aviation forecast with another weak flow, moist
boundary layer and poor model performance scenario. Anticipate
lingering MVFR ceilings will dissipate in the next hour or two,
only to redevelop MVFR ceilings later this tonight as boundary
layer cools. Best chance for IFR appears to be at KRSL/KGBD, with
slightly lower chance at KHUT/KSLN. Chances at KICT are too low
to include as TEMPO group. Conditions will improve as surface
wind increases later tomorrow morning. -Howerton
&&
.FIRE WEATHER...
Issued at 312 PM CST Sat Mar 11 2017
Southerly winds will increase and become gusty on Sunday ahead of an
approaching trough. Gusts of 30-35 mph should lead to very high
grassland fire danger values generally to the northwest of the
Kansas Turnpike. Minimum afternoon relative humidities will be 40-
45% based on latest projections. Scattered showers are possible as
the trough moves through the region Sunday night. Gusty
northwesterly winds 15-25 mph and drier air will lead to high
grassland fire danger Monday afternoon area-wide. Fire danger levels
should decrease to low Tuesday and Wednesday with lighter winds and
cool temperatures in place.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 25 49 34 48 / 20 0 20 0
Hutchinson 24 51 31 47 / 10 10 20 0
Newton 24 48 31 45 / 10 10 20 0
ElDorado 25 49 33 47 / 20 0 30 0
Winfield-KWLD 26 50 36 50 / 50 0 30 0
Russell 22 57 27 46 / 0 10 30 0
Great Bend 24 57 28 48 / 0 10 30 0
Salina 23 51 29 45 / 10 10 30 0
McPherson 23 50 29 45 / 10 10 30 0
Coffeyville 26 52 37 50 / 40 0 50 0
Chanute 23 50 34 47 / 40 0 40 0
Iola 23 49 34 46 / 20 0 40 0
Parsons-KPPF 25 51 36 49 / 60 0 40 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...PJH
FIRE WEATHER...JMC
Area Forecast Discussion
National Weather Service Wilmington NC
1008 PM EST Sat Mar 11 2017
.SYNOPSIS...
A wave of low pressure moving across the southeastern states
will bring light rain and snow to the area late tonight into
Sunday. Small accumulations are possible inland. Another area of
low pressure will develop off the South Carolina coast Monday
and move northward Tuesday. Behind this low, very cold air will
move into the Carolinas, with hard freezes possible both Thursday
and Friday mornings.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1000 PM Saturday...A review of latest model guidance and
current observations show we are still on-track for a Sunday
morning snow event across the northern half of the ILM forecast
area. Current air temperatures are obviously much too warm for
snow, but a check of the 00z MHX sounding confirms that
sufficient low-level dry air is in place to allow plenty of
evaporational cooling to take place once precip starts. Look at
that observed dewpoint 3700 feet up: -1 degree F!
Aside from a few sprinkles after midnight, most places should
remain dry up through at least 4-5 AM Sunday. Precipitation
will then develop from west to east as weak to moderate
isentropic lift develops along the 300K theta surface up above
700 mb. The entire event should take only 4-6 hours in most
locations as dry air advecting in aloft should lead to the back
edge of the precip reaching the coast during the early to mid
afternoon hours.
Freezing levels currently 3500-4000 feet AGL are expected to
plunge to <500 feet along and north of a line from Florence and
Marion to Whiteville and Wilmington due to evaporational cooling
below the cloud base. Rain should mix with snow along this
line, and will probably change over to all snow for a 1-2 hour
period north of this line. This is perhaps best depicted by the
latest HRRR model which shows a burst of moderate snowfall
developing around daybreak across most of interior SE North
Carolina and portions of the SC Pee Dee region north of
Florence. While the specifics of this one particular model run
aren`t likely to verify, the idea of a burst of accumulating
snow developing in heavier precip rates is sound. NWS Raleigh
research back in the 1990s called these "snow islands" as they
were often embedded within areas of liquid rain.
Changes with this forecast included increasing PoPs Sunday
morning and lowering hourly temperatures within the region of
heaviest precip Sunday morning. Most other changes were minor.
No changes are being made to the Winter Weather Advisory with
this issuance, however portions of northern Columbus County
could see some small accumulations if the latest models verify,
and may need to be added to the advisory.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 230 PM Saturday...Coastal trough starts to take shape Sun
night as high pressure continues ridging down the coast. A
surface wave along the trough starts to strengthen Mon as the
flow aloft becomes more amplified and divergence aloft
increases. Based on the surface pattern the trough is likely to
remain just offshore Mon as the low starts moving north. While
isentropic lift will be present from almost the start of the
period, there will be very little in the way of available
moisture. Precipitable water values will be around 0.25" Sun
night. However, a significant increase in moisture Mon morning
will lead to steadily increasing rain chances with rain possible
as early as mid morning Mon, lasting into Mon night.
Precipitable water values peak at over an inch in the afternoon
and will remain close to an inch for much of the night, save the
brief period of time from 00Z-06Z when the narrow dry slot
wraps in. Strong isentropic lift Mon afternoon starts to weaken
in the evening as the low exits and the dry slot wraps in.
Although deep moisture will hang around into the overnight there
may be a lack of forcing, especially as the low pulls away from
the area after 00Z. May see some light wrap around rainfall Mon
night but think the most significant rainfall will be seen Mon
afternoon. Temperatures will run below to well below climo
through the period.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 330 AM Saturday...Winter will continue to be the theme
for this work week. Progged longwave pattern aloft illustrates
a well amplified upper trof will affect the Eastern 1/3rd of
the U.S. this period. As a result, looking at temperatures below
to well below normal climatological values. The start of this
period will be highlighted by sfc low bombing off the DELMARVA
and New England Coasts. Cyclonic flow sfc and aloft will
dominate across the FA under strong NW and quite gusty winds due
to the tightened sfc pg extending from the expansive low off New
England. Wind advisory thresholds may be a concern, likely
further north of the ILM CWA, for Tue but at this time models
indicate no. Pcpn will have ended during the pre-dawn Tue hours.
For Wed thru Fri, cold Canadian High pressure will ridge across
the area from the Western Great Lakes. Model MOS guidance
indicates a possible damaging freeze may occur Thu morning with
mid to upper 20s for lows. This will need to be monitored as
Blue Berry and Straw Berry plants remain quite vulnerable to any
cold.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...VFR conditions should continue up through at least
09z, but deteriorating conditions should develop afterward as a
wave of low pressure approaches and spreads light rain and snow
across the area.
The best chance of snow and attendant reduced visibilities
should occur at the LBT airport between 11-15Z. This is a
moderate to high likelihood event. The ILM and FLO airports
will see moderate chances of MVFR/IFR conditions due to snow. At
CRE and MYR chances are low that snow will cause any flight
category impacts. Low clouds should develop during the
precipitation event, with moderate to high potential of ceilings
falling below 1000 feet in the 13-19Z timeframe Sunday.
with speeds increasing to over 10 knots and gusty by mid-
morning.
Extended outlook...MVFR/IFR conditions are possible in rain and
low ceilings late Monday afternoon through Monday night. VFR
conditions should develop by late Tuesday morning and persist
through Thursday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1000 PM Saturday...A wave of low pressure will move off
the Southeast U.S. coast overnight, increasing northeast winds
late. These winds will further increase Sunday leading to Small
Craft Advisory conditions no later than tomorrow afternoon. No
significant changes have been made to the forecast with this
evening update. Across the coastal waters seas remain around 2
feet (locally 3 feet in the Cape Fear region) and shouldn`t
build significantly until close to daybreak Sunday. Rain may
begin to fall as early as sunrise but will become most prevalent
during the mid to late morning hours north of Murrells Inlet.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 230 PM Saturday...Period begins with SCA already in
effect and likely to continue for much if not all of it. Pinched
gradient ahead of developing low, which will eventually track
north along a coastal trough off the southeast coast, helps keep
northeast flow 20 to 25 kt Sun night into Mon. Winds shift to
southerly late Mon and westerly Mon night as the low
passes/exits. Seas running 3 to 5 ft Sun night build over 6 ft
on Mon, peaking at close to 10 ft Mon night.
LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 330 AM Friday...This period will be highlighted with SCA
conditions Tue thru much of Wed, with even the remote possibility
of Gales early Tue. The latter will depend on the strength and
timing of the intensifying and bombing low that will occur off
the DELMARVA Coast and/or off the New England Coast Tue into Tue
night. At this point, have the seas blossoming into possible
double digit heights at the start of Tue morning but should
quickly subside thru Tue night as strong onshore winds ahead of
the intensifying low become offshore and likely even stronger
due to CAA combining with a sfc pg that will in all likelihood
continue to tighten. Winds will finally be in a diminishing
phase by late Tue night thru Wed as Canadian High pressure
becomes the driver for winds across the area waters. The center
of this high will track across the area on Thu with winds and
seas progged to be at their lowest for this week. Thus a brief
reprieve to a very active week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Winter Weather Advisory from 4 AM to 2 PM EDT Sunday for
SCZ017-023-024.
NC...Winter Weather Advisory from 4 AM to 2 PM EDT Sunday for
NCZ087-096-105.
MARINE...Small Craft Advisory from noon Sunday to 6 PM EDT Monday for
AMZ250-252-254-256.
&&
$$
SYNOPSIS...TRA/III
NEAR TERM...TRA
SHORT TERM...III
LONG TERM...DCH
AVIATION...TRA
Area Forecast Discussion
National Weather Service Jacksonville FL
949 PM EST Sat Mar 11 2017
.UPDATE...
Increasing ascent expected to occur tonight as a mid to upper
level trough approaches the area from the west. Isentropic
upglide will strengthen in the next few hours with strongest lift
over the central and northern zones as low level flow turns south
and southwest. Scattered showers expected to break out over the
coastal waters in the vicinity of currently diffuse warm frontal
boundary extending near our southern marine zones based on
analysis of dewpoint and instability fields. As sfc winds turn to
the east and southeast over the srn zones...this will enhance low
level convergence and temperature gradient over the region
favoring frontogenesis along with a development of weak sfc low
along the warm front over the coastal waters. This combined with
shortwave approaching from the west will develop isolated to
scattered shower activity from around the I-10 corridor northward
into SE GA after about 09z/10z. Did not add any thunder overnight
and kept it in the coastal waters from prior fcst where the
better instability will be located (LI values -1 to -3). Main
changes in the update for tonight and early Sunday was to refine
POPS a bit based on the latest HRRR and 18z guidance from NAM and
GFS. Low temps generally in the lower to mid 50s tonight. Clouds
should continue to increase with cloudy skies developing after
06z. Forecast for Sunday generally unchanged with just some tweaks
to morning POPs and still looks looks showers likely for most of
the region.
&&
.AVIATION...
Increasing multilayered clouds tonight with MVFR ceilings
developing around the JAX metro areas and SSI after 06z.
Increasing chance of showers by 12z at all TAFs and have MVFR for
rest of TAFs by 14z due to ceilings and likely showers. Some
small chance of IFR cigs late tonight and Sunday morning. Light
winds from the northeast near 5 mph will become northeasterly near
10-15 kt on Sunday as developed frontal boundary shifts back
southward as sfc low offshore shifts east to southeast.
&&
.MARINE...
Winds and seas briefly relax tonight as pres gradient become loose
and weak low pressure tries to form about 20-60 nm out. The low
pressure will move east and southeast Sunday and drag a cold front
back south again with a rapid increase in winds to 20-25 kt. A
Small Craft Advisory will go into effect Sunday morning for the
southeastern Georgia waters and the northern half of the Florida
waters. Little overall change in the forecast at this time.
Rip Currents: Solid moderate risk for Rip Currents continues
through the weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 50 59 45 62 / 30 60 20 30
SSI 55 61 52 65 / 40 70 40 30
JAX 55 66 53 70 / 40 70 40 50
SGJ 60 68 58 71 / 40 70 50 60
GNV 55 71 54 73 / 20 60 30 60
OCF 57 75 57 74 / 10 60 30 60
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...Small Craft Advisory from 11 AM Sunday to 11 AM EDT Monday for
Coastal waters from Altamaha Sound to Fernandina Beach FL
out 20 NM-Coastal waters from Fernandina Beach to St.
Augustine FL out 20 NM-Waters from Altamaha Sound GA to
Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina
Beach to St. Augustine FL from 20 to 60 NM.
&&
$$
Shashy/Peterson
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
515 PM CST Sat Mar 11 2017
.SYNOPSIS...
Issued at 253 PM CST Sat Mar 11 2017
H5 analysis this morning has broad northwesterly flow
across the western half of the CONUS. Low amplitude ridging extended
from southern Idaho into southeastern British Columbia. Off shore of
British Columbia, a shortwave trough was noted per WV imagery.
Across the central CONUS, a tandem of shortwaves were noted, the
first extended from southern North Dakota into eastern South Dakota.
A second wave was noted over southwestern Nebraska. Further east,
closed low pressure was noted over eastern Quebec with a trough
extending south into New England. At the surface, arctic high
pressure was located over southern Manitoba and has forced a cold
front through most of the plains and west against the front range of
the Rockies. This front has shown signs of pushing east as a warm
front as warmer air has pushed into northeastern Colorado and the
southwestern Nebraska panhandle this afternoon. Across western and
north central Nebraska, skies remained mostly cloudy and
temperatures ranged from near 30 in the northern forecast area, to
near 40 in the south and western forecast area.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 253 PM CST Sat Mar 11 2017
In the short term, temperatures and the threat for
light precipitation Sunday afternoon is the main forecast challenge.
Arctic high pressure, currently over southern Manitoba, will slid
east into western Ontario tonight. At the same time, surface low
pressure will begin to deepen over northeastern Wyoming. A warm
front will push through the forecast area tonight, ending up in
eastern Nebraska by Sunday morning. Clouds, and a shift in the winds
behind the exiting warm front, will lead to lows in the upper 20s to
lower 30s. On Sunday, low pressure will track across southern South
Dakota with a trailing cold front pushing through the forecast area
by 00z Monday. The timing of the front will be such that locations
in the southern and southeastern forecast area, should see highs in
the lower 60s Sunday. Locations in the northern forecast area, will
see highs around 50. By Sunday afternoon, a weak upper level
disturbance will track from the western Dakotas into central
Nebraska by 00z. Light rain showers will be possible INVOF the front
Sunday afternoon and have left pops in the forecast Sunday
afternoon.
.LONG TERM...(Sunday night through Saturday)
Issued at 253 PM CST Sat Mar 11 2017
Sunday night through Tuesday: Arctic high pressure will fill in
behind the exiting clipper system Sunday night. This will force an
arctic front west into the Nebraska panhandle overnight. This
feature will remain stationary for 6 to 12 hours before lifting
east into the eastern panhandle and southwestern Nebraska Monday
afternoon. H85 temps range from -13C in the northeast to 7C in the
far southwest, so a wide range in high are expected Monday. Highs
will range from the mid 20s in the far northeast to the lower 50s
in the southwest. On Monday night, a nice area of mid level
frontogenesis will spread from the central Dakotas into northern
then eastern Nebraska. Light snow will be possible INVOF this area
of frontogenesis Monday night into early Tuesday morning mainly
over the eastern third of the forecast area. On Tuesday the
surface front will remain anchored across central portions of the
forecast area. Like Monday, a wide range in high temperatures is
expected with lower 30s in the northeast to near 60 in the far
southwest.
Tuesday night through Saturday: The warm front will push into
eastern Nebraska on Wednesday as a ridge of high pressure builds
into the Rockies. Highs will finally reach the 40s in the east for
Wednesday with 60s forecast in the west. The ridge will build east
onto the central plains Thursday. H85 temps Thursday afternoon will
reach 10 to 16 C across the forecast area with 60s to mid 70s
forecast for highs. A shortwave aloft will over top the central CONUS
ridge Thursday night, forcing a cold front through the area. Showers
will be possible with passage of the front. ATTM forcing appears
strongest across northern Nebraska and will confine pops to these
areas. The cooldown behind the front will be temporary Friday, as
highs will reach back into the 60s for Saturday
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 515 PM CST Sat Mar 11 2017
VFR/ areas MVFR CIGS are expected overnight through 00Zz Sunday
evening.
A developing warm front...currently across Wrn Neb...lifts north
tonight and Sunday morning. The warm front is expected to produce
MVFR cigs...mainly east of highway 83. Similarly, MVFR cigs
embedded in arctic air across Nrn Neb this afternoon lift north
early this evening. The SREF and ECM were the basis for this
portion of the forecast. The GFS/NAM models were more agressive
with the warm front lifting north tonight and produce a more
widespread MVFR CIG event.
A strong cold front will move into Nrn Nebraska 18z-21z Sunday.
The HRRR and NAM models suggest scattered showers may develop off
the WY Big Horn range around 15z Sunday and affect Wrn and Ncntl
Nebraska as the front moves south 18z-00z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Melbourne FL
903 PM EST Sat Mar 11 2017
.UPDATE...
Tonight...High pressure to the north will elongate eastward into the
Atlantic and winds will become southeast after midnight. Evening
soundings showed a large dry layer over the top of a shallow layer
of more moist air. There have been a few small showers over the
Atlantic and a slight chance should continue as the winds become
southeast, but don`t expect them to reach land. Considerable mid to
high level cloudiness will spread over the area well ahead of
approaching upstream perturbation aloft. This cloudiness should
mitigate significant fog formation. Low temps in the lower to mid
60s except upper 50s in Okeechobee. No significant changes to the
current forecast.
&&
.AVIATION...
Mainly VFR expected overnight. Local MVFR BR possible at a few
sites, but no significant fog expected due to increasing mid-high
level clouds. The HRRR model indicates scattered showers forming
towards midday Sunday as moisture depth increases ahead of weak
disturbance aloft. The model showed a little bit of lightning in a
few of its hourly runs, but surface heating looks limited, so only
carried VCSH in the previous TAFs, though mid level temps will be
quite cold.
&&
.MARINE...
Tonight-Sunday...Winds will veer out of the east then southeast
overnight as high pressure ridge axis to the north elongates
eastward into the Atlantic. Also, there will be an inverted trough
just offshore northeast FL. The pressure gradient should support 10-
15 knots across all the waters. No headlines needed overnight.
Sunday...A tricky wind forecast due to uncertainty with the inverted
trough. The models generally show it pushing slowly east with a
wedge of north/northeast winds working down from the north on its
west side. The NAM is most aggressive while the GFS/ECMWF hold it
off until afternoon. Don`t see enough to make any changes to the
current forecast.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Lascody/Blottman
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
552 PM CST Sat Mar 11 2017
.SHORT TERM...(This evening through Sunday)
Issued at 345 PM CST Sat Mar 11 2017
Although confidence has increased enough to warrant a winter storm
warning along and southwest of the Minnesota River Valley, there
remains uncertainty on how much the drier air will play a role
during the onset of snow on Sunday. First, there is no question
that most of central and southern Minnesota, and west central
Wisconsin will see light snow before Monday afternoon. The main
question is how fast does the very dry air mass overhead begin to
saturate the low levels of the atmosphere and allow snow to fall
to the surface. Dew points this afternoon are slightly higher
than yesterday, but humidity levels remain very dry in the 20-30%
range in the boundary layer. Just as a previous winter storm that
had a very sharp gradient of where the snow fell, to nearly
nothing on the northwest side, this system has similar
characteristics. However, the orientation of the sharp snow line
is different. Another aspect to this storm is the relatively
short period of strengthening Sunday before the main forcing moves
south/southeast of Minnesota by Sunday night. This forcing is
associated with a strong thermal gradient oriented from west
central to south central Minnesota Sunday morning, through Sunday
afternoon. This is where the best frontogenesis, omega and the
dendritic growth zone coincide.
Initially the dry air mass needs to saturate which might be
easier in southwest Minnesota due to the current system leaving
behind some moisture in the boundary layer. However, further to
the east/northeast the air mass may take a few hours to saturate
leading to lower confidence on snowfall amounts. The dendritic
zone does last longer further to the east across south
central/east central Minnesota Sunday afternoon, but the forcing
is weaker and may hold off on accumulating snowfall until the late
afternoon. Another aspect to this storm is the concern with
snowfall ratios which initially will be 18/20-1 in eastern
Minnesota, to 15/17-1 in southwest Minnesota. These numbers will
rise during the day, so the combination of snowfall ratios and qpf
amounts will be critical on snowfall totals, especially Sunday as
the atmosphere saturates in the boundary layer.
.LONG TERM...(Sunday night through Saturday)
Issued at 330 PM CST Sat Mar 11 2017
Longer term concerns remain placement of the heavier snow band and
overall headline resolution.
Model trends indicate heavier snow will be ongoing over south
central MN during the evening. Best vertical velocity in the
dendritic growth zone remains over the southwest metro by late
afternoon and shifts into south central MN mainly after 00z Mon. We
do feel model qpf may be a bit high...especially on the NAM...which
also seems to shift heavier snow band farther to the northeast.
Also...adjusted the SLR values during the evening as well... with
18t to 20:1 a bit high when compared with the COBB and other model
trends...especially to the south. A more 14-17:1 ratio looks be
better here. Meanwhile...the 12z GFS holds onto its snow band
placement...mainly to the southwest. Looking at the GEFS probability
trends last few runs...they have shown pretty good continuity with
the >6 inches snow accumulation in 24hrs...which places it along the
Minnesota River Valley region. Still have time to monitor one last
model run to finalize over all headlines. The bulk of the snow
should occur before 12z Monday across the area...with some lingering
light snow possible over the eastern cwa Monday morning. Wind
concerns appear minor at this time with wind gusts around 20 to 25
mph expected at the tail end of the accumulating snow.
We see cooler air to follow the system through Wednesday with a
gradual warming trend...above normal into next weekend. The
deterministic runs diverge some on how much warm air lifts northeast
into the area...ahead of the next trough. It looks warm enough for
at least a rain/snow mix...if not all rain developing during the day
Friday the surface cold front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 552 PM CST Sat Mar 11 2017
Model agreement is quite high with snow coming in Sunday, with one
thing of note being that the hrrr is coming in an hour or two
slower than the GFS/NAM, which makes sense given very dry initial
airmass. As a result, not much was changed with existing TAFs
other than to delay snow onset an hour or two. Heaviest snow still
expected at RWF, with vis 1/4sm or less in snow at times possible
there 18-22z. All other terminals look to only drop as low as
3/4sm in snow with heaviest snow running down the MN River toward
AEL.
KMSP...High confidence in forecast, including with arrival of
snowfall Sunday. Expect snow to start within 90 minutes of what
current TAF has. Only thing that may be different is we may come
out the gate with 1sm vsby as opposed to current MVFR vis
indicated. Heaviest snow, with rates between 3/4" and 1" per hour
expected between 20z and 1z. These kind of rates will likely
necessitate an AWW as the event draws closer. Expecting snow
totals in the ballpark of 4" at MSP with this event.
/OUTLOOK FOR KMSP/
Mon...MVFR/IFR with -sn early, then VFR. Wind bcmg N 5-10 kts.
Tue...VFR. Wind NE 5 kts.
Wed...VFR. Wind becoming S 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Winter Storm Watch from Sunday afternoon through Monday
afternoon for MNZ059-060-068>070-076>078-083>085-092-093.
Winter Storm Watch from Sunday morning through Monday morning
for MNZ047>049-055>058-065>067-075.
Winter Storm Warning from 10 AM Sunday to 7 AM CDT Monday for
MNZ054-064-073-074-082-091.
&&
$$
SHORT TERM...JLT
LONG TERM...DWE
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
550 PM EST Sat Mar 11 2017
.SHORT TERM...(This evening through Sunday)
Issued at 411 PM EST SAT MAR 11 2017
WV imagery and RAP analysis indicated confluent wnw mid/upper level
flow through nw Ontario and the nrn Great Lakes between a mid level
low over the Canadian maritimes and a ridge building into the west.
At the surface, nw flow prevailed through the cwa ahead of 1045 mb
high pres from Saskatchewan/Manitoba into the ern Dakotas. Vis
satellite and radar showed weak multiple wind parallel LES bands
mainly over the cntrl and ern lake as very dry air upstream has
limited band formation closer to the shore in the west with only
very light snow.
Tonight, the LES should slowly increase again as a weak clipper
shortwave and jet streak slides toward the region. Since the
shortwave will begin to shear out and provide only weak forcing,
inversion heights will climb from around 4k ft to 5k-6k ft into
Sunday morning. Winds will also slowly veer to the nnw or n. As
winds diminish from 20-30kt to 10-20kt overnight the LES bands will
also become influenced by land breeze and lake induced troughing
which may keep the stronger convergence between Marquette and Grand
Marais. Overall accumulations will remain on the light side with 12
hour accumulations of 1 to 3 inches tonight. Even drier air and a
shorter fetch over the west will limit accumulations to an inch or
less.
Sunday, more anticyclonic flow develops as the ridge continues to
build into the area and inversion heights lower to around 4k
ft keeping additional accumulations to an inch or less.
.LONG TERM...(Sunday night through Saturday)
Issued at 331 PM EST SAT MAR 11 2017
Focused attention on Sun night into Wed when models suggest
persistent NE wind upslope/lake enhancement as a couple shortwaves
move through the region. After That, just kept with the blended
initialization.
With 850mb temps around -20C for the most part Sun night into Wed
and winds from the NE gradually turning to the N on Tue, lake
enhancement of the shortwave energy will certainly occur, along with
upslope enhancement. N central Upper MI looks to have the highest
potential to see the best snowfall of generally 2 or so inches per
12 hours Sun night through Tue night, with the potential for
heaviest snow of 3-4 inches per 12 hours on Mon as the shortwave
drops in. Not overly confident on snowfall amounts given that models
seem to have a very poor handle on the upslope/lake enhancement.
There will be dry air to deal with after the shortwave moves through
Mon night onward, but the combination of NE-N wind fetch and upslope
enhancement should be able to overcome that.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 550 PM EST SAT MAR 11 2017
NW wind lake effect will continue through Sunday morning before
diminishing. KIWD and KCMX will see the main impacts from the lake
effect snow. Conditions will be mainly MVFR with ocnl IFR cigs as
the snow bands slide across the TAF sites. Expect some improvment
Sunday morning as drier air moves into the region. Even as winds
veer more to the nnw, KSAW will see mainly cigs at or above MVFR
with VFR vsby as the heavier LES bands remain to the east
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 411 PM EST SAT MAR 11 2017
Northwest winds to 30 knots this evening will gradually diminish as
high pressure builds into the region. As a result, the heavy
freezing spray will diminish. No gales or heavy freezing spray is
expected beyond that period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until midnight EST tonight for MIZ006-
007-085.
Lake Superior...
Heavy Freezing Spray Warning until 1 AM EST Sunday for LSZ266-
267.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Titus
AVIATION...07
MARINE...JLB