Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/12/20
Area Forecast Discussion
National Weather Service Des Moines IA
710 PM CDT Sat Apr 11 2020
...Updated Aviation Discussion...
.DISCUSSION.../Tonight through Saturday/
Issued at 306 PM CDT Sat Apr 11 2020
Initial push of warm advection and moisture into the state has
produce scattered showers and a few storms across Iowa today. This
initial surge continues eastward into this evening with
precipitation spreading into eastern Iowa and northern Illinois.
Additional scattered showers and thunderstorms seem likely across
the south again later this evening into the overnight as another
weak wave passes through near the Iowa/Missouri border. Meanwhile,
a strengthening boundary will slowly into central Iowa overnight as
low pressure deepens across the Plains. Wind fields are forecast to
intensify through the night as the pressure gradient tightens with
increasing cold advection into northwest Iowa.
Forcing increases significantly into Sunday with the approach of the
northern stream shortwave. Precipitation will increase in coverage
and intensity into the morning across behind the boundary across the
northwest third of Iowa. Models have trended slightly farther north
with axis of main forcing and resultant QPF and this needs to be
monitored in further runs. Impressive mid level QG and
frontogenetical forcing will be ongoing for a good portion of the
day across the north with banded snowfall likely. In addition,
stability is quite weak with thunder possible in the far north
enhancing snowfall rates. Rates of 1-2" seems quite possible near
the Minnesota border for a few hours into Sunday afternoon. Amounts
in the far northwest will likely be from 8-10" but could be even
high should convective elements develop. The gradient of snow will
be tight on the south side of the band where warmer air is expected
to keep precipitation mainly liquid prior to the heavier QPF ending
towards evening. Otherwise, winds strengthen during the day and
into the evening with near blizzard conditions in the warning areas.
A possible upgrade seems in the cards should the wind fields
develop, although fracturing of stucco snow to reduce visibilities
is somewhat difficult. Elsewhere, a wind advisory also seems likely
to be issued in future forecasts as the top of the mixed layer is
mostly 40-50kts in most locations later Sunday into Sunday night as
strong cold advection spreads across the state.
HRRR has been showing some decent instability in the far southeast
by Sunday afternoon and there is some concern that the potential is
being underplayed. Shear is not a problem with this system so
everything depends on the ability for instability to develop given
the extensive cloud cover and track of surface low. This will need
to be closely watched with damaging winds and large hail possible,
if greater instability would develop, a tornado would not be out of
the question either.
After the storm departs late Sunday night into early Monday, thermal
trof will enter the state on Monday with a brisk and cold day. Some
lingering clouds may persist in the north through the day given the
cyclonic curvature and the approach of a weak shortwave late in the
day. The overall upper pattern remains unchanged through the mid to
late work week with a large upper trof continuing across the eastern
half to two-thirds of the nation. This will keep open the reservoir
of unseasonably cold air into the state during the work week with
temperatures holding 15-20 degrees below normal for much of the
time. Some slight moderation is expected by late in the period as
the deep trof begins to migrate east with the amplitude of the upper
flow flattening, allowing for some modification of the airmass in
the Midwest. Chances for precipitation through the week will be
limited with any rain/snow remaining light and rather limited in
spacial extent.
&&
.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 700 PM CDT Sat Apr 11 2020
VFR conditions this evening before the rain/snow develops by early
Sunday morning. Ceilings will gradually lower late tonight and
into the overnight hours and confident by 8-12z Sunday, at least
IFR ceilings should be present. Lower confidence in the visibility
restrictions and kept mainly MVFR until the strong winds develop
late in the morning Sunday. Also, FOD, ALO and MCW will see snow
toward the end of the TAF period and higher confidence in the
lower visibility restrictions coupled with the potent northwest
winds.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 10 AM Sunday to 4 AM CDT Monday for
IAZ016-017-023-024-033-034.
Winter Storm Warning from 7 AM Sunday to 4 AM CDT Monday for
IAZ004>007-015.
&&
$$
DISCUSSION...Cogil
AVIATION...Podrazik
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1100 PM CDT Sat Apr 11 2020
.SHORT TERM...(This Evening through Sunday Night)
Issued at 321 PM CDT Sat Apr 11 2020
At a synoptic level, WV satellite imagery and upper level
analysis shows a pronounced closed low across southern AZ with a
southern stream jet running across the southern CONUS and a
strengthening northern stream jet from the eastern Dakotas
eastward toward the Great Lakes. Closer to home in the form of
more sensible weather, a couple of different areas of showers, one
in NW IA and the other near and west of the James River. With
temperatures in the 50s to even lower 60s, this has all been rain
and should remain that way into the evening.
By tonight, the more impactful weather begins as the right entrance
region of the previously mentioned northern stream jet begins to
induce and strengthen mid level frontogenesis. Guidance continues
to suggest this frontal forcing is strongest in the 700:800 mb
layer initially running near the MO River Valley across south
central SD and eventually settling in from northeast NE, far
southeast SD, and then toward south central MN, north central IA.
Guidance also continues to depict some negative EPV* just atop
this layer suggesting the potential for a contracting and
enhancing of the strongest snow band (more on this later). All of
this should establish a fairly coherent and robust band of
precipitation through the second half of the overnight into much
of the daytime hours Sunday. Better forcing should shift east of
I-29 by early to mid evening with upper level subsidence shutting
down the remainder of the precipitation across our area after
midnight Sunday night.
Precipitation Type: Forecast soundings suggest we should see a
fairly clean transition from rain to a brief rain/snow mix to snow
for most locations. The transition from rain to snow should be
underway by late evening west of the James River working eastward
with a changeover around or just prior to the daybreak hours along a
Yankton to Sioux Falls to Worthington line. The remainder of NW IA
may be closer to the mid morning hours, although likely much
dependent on precipitation rates and potential for dynamical
cooling. Areas near Ida Grove and Storm Lake will be the last to see
the switch to snow with perhaps even a period of sleet or freezing
as the colder surface air outruns a pocket of warmer air aloft. A
few rumbles of thunder are also possible across this area.
Amounts: Model progged PWAT are not anything abnormal in terms of
climatology but the strong dynamics of this system should still
produce some healthy QPF amounts. As previously mentioned, still
plenty of suggestion in the models that we may see a tighter and
heavier band of snowfall develop which may drive a narrow
corridor of higher amounts. As is typical in these scenarios,
agreement on where exactly this will end up is far from agreed
upon although have noted a northward shift in guidance over the
past 12 to 24 hours. The HRRR and RAP are generally furthest north
with this area of higher QPF near and north of I-90 and NAM (and
its derivatives), GFS and ECMWF south of I-90. SREF and WPC super-
ensemble plumes further display this uncertainty with some
locations exhibiting as much as a 0.75 to 1 inch spread in QPF. A
couple of different options exist for a snowfall forecast...The
first would be to continue to play the northward shift (HRRR/RAP)
which after collaborating with WPC, wouldn`t be the first system
recently to do this. The other thought is to follow the better mid
level frontal forcing (NAM/GFS/EC) which is generally what this
forecast package relied on. This also aligns relatively well with
the HREF probability matched mean. This would put a band of 6 to
10+ inches from roughly Gregory to Beresford to Worthington with
generally 2 to 6 inches buffering that. With all of that said, a
quick cursory glance at the 18z guidance just coming in gives a
little more credence to a northern solution.
Impacts: Ground temperatures across the region are largely in the
40s with road temperatures likely higher than that. This may work to
temper the travel impacts some, although with snow rates nearing or
exceeding 1 inch per hour at times (supported by HREF
probabilities and periods of deep dendritic layers exhibited in
various soundings), these warmer ground temperatures should have
no problem becoming overrun. This will result in slushy or
snowcovered roads. Additionally, winds at the top of the mixed
layer sit anywhere from 30 to 40+ kts which will help to produce
winds gusts of at least 35 to 45 mph. This will result in some
blowing snow and reduced visibility which given the expected wet
nature of the snowfall, should be mainly confined to period of
falling snow.
Headlines: Have upgraded the remainder of the previous watch with an
additional northward bump. This warning area may still need to be
shift a row of counties or two (more likely north than south at
this point) depending on where the final consensus for the
heaviest corridor settles in. Have also covered the remainder of
the coverage area with an advisory given the combination of snow
and wind.
.LONG TERM...(Monday through Saturday)
Issued at 321 PM CDT Sat Apr 11 2020
With an active period in the shorter terms of the forecast, minimal
changes were made in the extended portions of the forecast. Stubborn
upper level troughing will no doubt keep our region below normal as
far as temperatures with high temperatures thru Tuesday likely
stuck in the 30s. May see some moderation later next week but
still hedging toward below normal readings. A fairly disturbance
ridden northwest flow aloft regime will keep us from staying
completely dry during this time frame, although tough to pinpoint
details on exact timing of any waves at this point. Significant
precipitation doesn`t look overly likely beyond the weekend
however.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1051 PM CDT Sat Apr 11 2020
Light rain is moving across the area, with the transition to snow
already occurring for areas in central to east central SD,
including KHON and K9V9. Snow transition for KFSD, KSUX, and
surrounding areas expected before daybreak. Conditions will
continue to deteriorate, with snow becoming heavier and northerly
winds increasing through the morning, gusting up to 40 knots. IFR
visibility and ceilings are expected, with LIFR conditions
possible within the heaviest snow band and coupled with blowing
snow. Conditions will begin to improve from west to east as the
snow tapers off late Sunday afternoon through evening.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for
SDZ066-067-069>071.
Winter Storm Warning until 4 PM CDT Sunday for SDZ050-057-
063>065-068.
Winter Weather Advisory from 4 AM to 7 PM CDT Sunday for SDZ040-
055-056-061-062.
Winter Weather Advisory until 4 PM CDT Sunday for SDZ038-039-
052>054-058>060.
MN...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for
MNZ080-081-089-090-098.
Winter Weather Advisory from 4 AM to 7 PM CDT Sunday for MNZ071-
072-097.
IA...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for
IAZ001>003-012>014-020-021.
Winter Weather Advisory from 10 AM Sunday to 1 AM CDT Monday for
IAZ022-031-032.
NE...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for
NEZ013.
Winter Weather Advisory from 10 AM Sunday to 1 AM CDT Monday for
NEZ014.
&&
$$
SHORT TERM...Kalin
LONG TERM...Kalin
AVIATION...SG
Area Forecast Discussion
National Weather Service Grand Junction CO
548 PM MDT Sat Apr 11 2020
.SHORT TERM...(Tonight through Sunday night)
Issued at 214 PM MDT Sat Apr 11 2020
The much-touted cold front remains to our north this afternoon.
We`ve seen plenty of warm temperatures and some higher gusts this
afternoon and this will continue as we head into the evening
hours. Also, radar is just starting to show some development along
the UT/CO border this afternoon which follows the HRRR forecast
and is also where the best CAPE lies. Peak heating and a
marginally unstable atmosphere ahead of the cold front should
allow some showers to form and a few rumbles of thunder through
this evening, mostly for our northern valleys.
As far as the cold front is concerned, we`re still on track to
see it move through overnight. It will be noticeable to most
people as it moves through due to some gusty winds and
accompanying precipitation. Guidance still showing the Flat Tops,
Park and Elkheads seeing the best shot of some accumulating snow
so the going advisories remain in effect. Any snow that does
accumulate will quickly melt off Sunday morning once the sun
rises. The northern San Juans and West Elks will also likely see
some snowfall but amounts look to be in 3 to 6 inch range so held
off issuing anything for now.
Once the front moves through, we can expect variable cloudiness
Sunday though some lingering showers will continue along the
Continental Divide. Passage of the front will cause winds to shift
to more northerly as cold advection kicks in bringing in cooler
temperatures to the region. Normally, the coldest temperatures are
found the second day after frontal passage and that will hold true
with this front. Temperatures will be cooler Sunday but as the
cold advection is just starting, the noticeably colder air won`t
be here until Monday.
.LONG TERM...(Monday through Saturday)
Issued at 214 PM MDT Sat Apr 11 2020
While the calendar says it`s spring, many of us will wake up Monday
morning and think it`s winter. When cold air moves in, MOS (or
statistical guidance) is one of the first indicators that we`ll see
cold temperatures moving in. Many times, as we get closer to the
event, MOS guidance will start to warm up these cold temperatures.
This time, they`ve stayed the same or gotten colder so confidence
remains high that we`ll be seeing these cold temperatures Monday
through Wednesday before things start warming up. As we`ve
mentioned for many days now, the culprit was the cold front that
moved through Saturday and Sunday. A trough then sets up and
affects the entirety of the CONUS while remain remain on the
western side of the trough axis. This will allow northwesterly to
northerly mid to upper level winds to advect in much cooler air
from the north. The growing season looks to have started for the
Grand Valley, Moab, and also Montrose areas which is a concern.
Hard freezes look probable for the Grand Valley and Montrose areas
while Moab will be flirting with these values (<=28F) so issued a
Freeze Watch for both Monday and Tuesday...and we might need one
for Wednesday as well.
As far as any precip is concerned, models indicate a few weak
waves bringing light precip to the higher terrain mostly north of
the I-70 corridor Monday evening and again Tuesday evening.
Moisture is meager at best with forecast QPF amounts only reaching
.01 inches through both days. Thus, expect isolated to scattered
showers but little in the way of accumulation. The GFS likes the
idea of orographically- enhanced snow for the Park and Elkheads
early Wednesday morning while the EC keeps that area dry. The
National Blend of Models likes the idea of this scenario and it
seems reasonable so slight chance to chance showers for that area
looks good.
A stronger wave is then progged to move down from the north
Wednesday evening into Thursday. It`s the evolution of this feature
that is suspect as the EC brings an elongated trough through early
Thursday morning and absorbs a shallow area of low pressure off the
California coast whilst keeping precip over much of our CWA. The GFS
favors a stronger low off the coast and the trough staying separate
as it moves through. Either way, looks like some precip and
unsettled weather early Thursday morning through Saturday and
possibly beyond. Low to medium confidence at the moment as models do
differ quite a bit. Temperatures will stay below average until
Friday/Saturday when then finally get near climatological norms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 548 PM MDT Sat Apr 11 2020
A storm system and its associated cold front will move through the
region beginning this evening and will keep pushing south
overnight. Showers are likely to impact KHDN, KRIL, KEGE, KASE
before midnight with KMTJ, KGUC and KTEX joining the action later
tonight. Precipitation is likely to begin as rain or a rain snow
mix, turning over to all snow for all but KMTJ. Hedged toward MVFR
visibility, though brief periods of IFR and possibly LIFR are
possible with convective showers. Lightning is possible for KHDN
and to a lesser extend at KEGE and KASE. Ceilings will be an issue
for KRIL, KEGE and KASE from late evening into Sunday morning
where cloud decks are likely to fall below ILS minimums. Gusty
winds before and after the front with a wind shift are expected to
impact all TAF sites as the system passes through the region.
Finally, conditions improve during the afternoon, though mountain
snow showers will continue over the mountains of the Continental
Divide throughout the day.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Freeze Watch from late Sunday night through Monday morning for
COZ006-011.
Freeze Watch from late Monday night through Tuesday morning for
COZ006-011.
Winter Weather Advisory until 6 PM MDT Sunday for COZ004.
Winter Weather Advisory from midnight tonight to 6 PM MDT Sunday
for COZ010-013.
UT...Freeze Watch from late Sunday night through Monday morning for
UTZ027.
Freeze Watch from late Monday night through Tuesday morning for
UTZ027.
&&
$$
SHORT TERM...TGR
LONG TERM...TGR
AVIATION...NL
Area Forecast Discussion
National Weather Service North Platte NE
648 PM CDT Sat Apr 11 2020
.SHORT TERM...(This evening through Sunday night)
Issued at 353 PM CDT Sat Apr 11 2020
The primary forecast challenges the next few days revolves around
the incoming winter storm followed by unseasonably cool conditions.
So far today, a surface cold front bisects the forecast area,
generally laying along Hwy 2 as of 20z. Mid level frontogenesis has
been increasing across northern Nebraska per RAP mesoanalysis and
scattered rain showers. Isentropic analysis also indicates broad
lift, while decent low level moisture advection is occurring over
southwest Nebraska as dew points approach 40F.
This evening and tonight... Ingredients continue to come together
for a potent winter storm to affect western and north central
Nebraska. The primary surface low deepens as it spins up over the
CO/KS plains. Meanwhile, the heart of the upper trough traverses the
Dakotas, but strong forcing stretches into northern Nebraska. In
between, strong CAA takes over at H85 with temps dropping to around -
9C. The combination results in scattered activity becoming more
widespread across northwest Neb, then overspreading the rest of the
Sandhills overnight. Precip will remain as rain through about 03z,
then a transition to snow begins in northern Sheridan and Cherry
Counties. The switchover slides southeast overnight to where the
whole forecast area should be snow by 12z. The latest guidance,
including CAMs, suggests more scattered nature of the precip across
SW Neb due to some dry air intrusions below H7 and weaker forcing at
H7-5. However, a mesoscale band is possible toward dawn, which may
be responsible for most of the snow accumulation there. The
Sandhills, and particularly areas near the SoDak border, feature the
best combination of moisture and forcing. Snow totals have lowered
slightly southwest (generally 1-2") and along Hwy 2 (mainly 2-4"),
while totals have changed little across the northern Sandhills (5-
7"). With that said, kept all headlines the same. Much of the
accumulation will occur within about a six hour window, where snow
rates will approach 1"/hr at times. Across the north, X-sections
indicate some theta-E folding, and forecast soundings indicate more
of the thermal profile landing in the DGZ. Along with the snow, wind
is a major factor with this system. The sfc low makes a large
pressure gradient, while the shortwave and nearly unidirectional
flow below H7 help mix greater speeds down. Northerly winds steadily
increase through the night with gusts topping 40mph by 12z.
Significant blowing and drifting is expected, but the the wet nature
of the snow and low SLR`s to start should keep conditions below
blizzard criteria.
Sunday... Snow continues across the forecast area during the
morning, then tapers fairly quickly from west to east in the
afternoon. Winds strengthen further through about 18z, then slowly
wane into the evening. Peak gusts range from around 40 mph north to
50+ mph in the south, aided by nearly 2mb/hr surface pressure rises.
Even as the falling snow comes to an end, blowing snow will remain a
concern. Will need to watch for a second round of light
snow/flurries in the panhandle late afternoon to early evening as
upslope flow resumes. Pushed max temps down a degree or so from
previous forecast using the cooler guidance. Highs range from upper
20s along the Pine Ridge to lower/mid 30s far southwest. Lows Sunday
night may not be cool enough due to fresh snow pack and clearing
skies. If winds trend lighter, this will be a setup for potentially
record lows. NAEFS ensembles suggest record cold H7 temps in
northern Neb and H85 temps cooler than 1% of climo.
.LONG TERM...(Monday through Saturday)
Issued at 353 PM CDT Sat Apr 11 2020
Monday and beyond... The large upper trough centered over the Great
Lakes slowly retreats eastward, but Nebraska remains in northwest
flow for the foreseeable future. A couple (very) weak boundaries
brush the area during the week, which will keep moisture chances
low. The best shot comes Thursday into Friday as a somewhat stronger
shortwave rounds the trough while upslope flow takes over closer to
the surface. Temperatures remain cool, including highs in the
30s/40s Mon and Tue and near record lows Monday night. Cross our
fingers for 60F by next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 611 PM CDT Sat Apr 11 2020
Multiple aviation concerns within the TAF period as a winter storm
impacts the region tonight-Sunday. Latest radar display shows
scattered rain showers across far northern NEB and isolated
showers across southwest NEB. Latest obs show VFR conditions
across much of the Sandhills and southwest NEB, except IFR
ceilings across extreme northwestern NEB. Current thinking is
greatest areal coverage of showers will be confined to northern
NEB late today/evening with just passing isolated showers to the
south. This evening will see a changeover to snow across
northwestern NEB with precipitation spreading gradually across the
area overnight, becoming snow as well. Meanwhile, ceilings will
deteriorate area-wide overnight down to IFR to low-end MVFR (less
than 2 kft) that will then prevail into early tomorrow before
improvement to low-end VFR (less than 7 kft) or high-end MVFR.
Meanwhile, visibility as low as 1/2 mile or less is possible at
times with moderate to heavy snow along with blowing snow. That
said, greatest snowfall is expected across northern NEB and parts
of the Sandhills, elsewhere generally an inch or less is forecast
across much of southwest NEB. Strong winds will develop tomorrow
with gusts as high as 40-50 mph as the low pressure system evolves
from the Central High Plains this evening towards eastern OK/MO
tomorrow.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM CDT /midnight MDT/ to 10 PM
CDT /9 PM MDT/ Sunday for NEZ022-035>038-056>059.
Winter Storm Warning from 1 AM to 10 PM CDT Sunday for
NEZ006>010-025>029.
Winter Storm Warning until 7 PM CDT /6 PM MDT/ Sunday for NEZ004-
005-023-024-094.
&&
$$
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...ET
Area Forecast Discussion
National Weather Service Miami FL
736 PM EDT Sat Apr 11 2020
.Aviation...
Showers and thunderstorms will continue to affect the east coast
terminals through the early evening hours. There could be periods
of MVFR to IFR across the terminals of Miami Dade County as these
thunderstorms move through this evening. Afterwards, VFR
conditions should prevail through the overnight hours and into
Sunday morning. Winds will increase out of the Southeast and they
will be gusty at times on Sunday.
&&
.Update...
Updated the forecast based on radar trends. Showers and
thunderstorms will continue this evening especially across Miami
Dade County as they move southeastward. These storms could contain
gusty winds, heavy rain,small hail, and funnel clouds as they
move through. As the evening progresses, these thunderstorms will
begin to diminish and many areas will dry out during the overnight
hours. Low temperatures tonight will remain on the mild side as
they will drop into the upper 60s across the northwestern interior
to the mid 70s across the east coast metro areas. On Sunday, the
winds will increase out of the southeast as the pressure gradient
across the region increases. Winds will be gusty at times during
the day on Sunday. A few showers are possible during the afternoon
hours especially across the Lake Okeechobee region. High
temperatures on Sunday will range from the mid 80s across the east
coast to the mid 90s across the interior sections.
&&
.Prev Discussion... /issued 217 PM EDT Sat Apr 11 2020/
Short Term...
Today...
A differential heating boundary has develop across central Miami-Dade
County where some clearing of stratiform clouds has allowed
increased heating across Southern portions of the peninsula. On vis
satellite you can also, a well-develop cu field beginning to form.
Winds have become a little backed and easterly at the surface, with
upper level HRRR model winds veering westerly with height. With the
increased heating MLCAPE values have soared to be above 3000 J/kg
over southeastern Florida with 50 to 60 knots of effective bulk
shear. 0-3 SRH values over the southeastern metro are 150-200 m2/s2
and significant tornado parameter (STP) indices around 1 over metro
Miami-Dade. The storm relative mean wind is oblique to the current
boundary axis across Miami-Dade county support semi-discrete
supercell storm mode. There is increasing potential for severe
supercells across southeastern Florida this afternoon, with main
hazards being damaging winds, large hail and even the possibility of
a tornadoes. If multiple round of storms develop over the same area
heavy rainfall may lead to localized flooding of low-lying poor
drainage.
Due to the weak ascent there is still some uncertainty that this
event will materialize.
Sunday and Monday...
High pressure will dominate for the beginning of the week. Even
so, a few showers may be possible in the Lake region. With the
high to the east, a south to southeast flow will bring a warming
trend to the area, helping to boost temps into the upper 80s to
low 90s.
Long Term (Tuesday through Friday)...
A cold front will stall around north central Florida on Tuesday,
permitting southern Florida to remain in the warm, moist airmass
around the Atlantic surface high pressure. As the week progresses,
a reinforcing front pushes across the southeastern United States
which will allow the boundary to advance southward into southern
and central Florida. The main stories through the rest of the week
will be warm temperatures and increasing rain chances. There is
still some uncertainty with the timing and location of the front
before it stalls. If the location is further south than currently
forecast, rain chances will increase while the increased cloud
cover may help cool temperatures a bit. Either way, the chances of
rain will include the potential for heavy rain as well, especially
with more robust convection like thunderstorms.
Marine...
Showers and thunderstorms may bring locally hazardous weather to
the Atlantic waters, including Biscayne Bay through this evening.
This includes gusty wind and waterspouts as possible hazards.
Then, conditions improve for the next couple of days as high
pressure builds in. Even so,wind may continue to be a concern for
small craft, as a south to southeast wind of 15 to 20kts is
forecast through at least the first half of the week. Small Craft
Should Exercise Caution, mainly in the Atlantic waters of South
Florida.
Aviation...
Unsettled weather is forecast across South Florida through the
evening hours. Strong gusty showers and possibly some isolated
strong to severe thunderstorms are possible, mainly south of
Alligator Alley. The hazards include hail, downbursts, and funnel
clouds are possible. Also, an isolated tornado can not be ruled
out. Active weather is possible well into the overnight hours.
Tomorrow should see quieter weather, but the wind is forecast to
be breezy out of the southeast.
Beach Forecast...
A southeast wind is forecast to strengthen for the next few days.
this would keep an enhanced risk of rip currents for the Atlantic
beaches for at least the first half of the week.
&&
.Preliminary Point Temps/PoPs...
West Palm Beach 74 85 76 89 / 30 20 0 10
Fort Lauderdale 75 85 78 87 / 30 20 0 0
Miami 75 85 77 88 / 30 10 0 0
Naples 72 90 75 88 / 0 0 0 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
Update...55/CWC
Aviation...55/CWC
Area Forecast Discussion
National Weather Service Marquette MI
1106 PM EDT Sat Apr 11 2020
.UPDATE...
Issued at 1105 PM EDT SAT APR 11 2020
Quick check of incoming 00z NAM/WRF-ARW/WRF-NMM runs strongly
support the overall look of going fcst for w and central Upper MI
with regard to the upcoming late season winter storm. All focus
heaviest pcpn amounts across the high terrain of Baraga/Marquette
counties where qpf of 1.75 to 2.25 inches is indicated by 12z Mon.
The axis of heaviest qpf then extends sw, centered generally
across Iron County. Snowfall will be very heavy across the warning
area Sun night and suspect that travel may become impossible for
some areas by Mon morning. New 00z CMC has not yet started
arriving, but it was noted that the 18z run took a decent shift
eastward with its heaviest qpf axis. Will be interesting to see if
the non-NCEP 00z models support the above scenario.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 438 PM EDT SAT APR 11 2020
WV imagery and RAP analysis indicated mainly zonal flow across the
northen CONUS with a shortwave trough sliding to the north through
northern Ontario. A vigorous upstream shortwave was moving through
northeast WA while a southern stream shrtwv was moving through sw
AZ. At the surface, the northern Ontario shrtwv and associated 1002
mb sfc low was dragging a cold front through western Lake Superior.
Mid/high clouds with the shrtwv tail and developing WAA pattern were
streaming through mainly western Upper Michigan. Otherwise,
plentiful sunshine has helped push temps into the mid 50s to aroudn
60, except along Lake Michigan where readings remained in the 50s.
Tonight, cooler air will move into the area with winds veering
northerly behind the cold front. However, with radiational cooling
limited by a continued increase in mid/high clouds, temps will only
drop to around 30.
Sunday, the deepening mid level trough over the Northern Plains and
a developing sfc trough from Oklahoma to northern Lower Michigan
will support strengthening deep isentropic lift over the region with
strong moisture transport toward Upper Michigan. The onset of the
heavier pcpn during the afternoon reflects a compromise between the
faster NAM and the slower GFS/ECMWF and high res models. After an
initial warmup into the mid to upper 30s, increasing pcpn with
evaporative cooling will change most of the pcpn quickly from any
rain or mix to snow. The exception will be close to Lake Michigan
Where the warm low layer may persist. Snow accumuations of a couple
inches will already be possible by early evening, with higher
amounts possible if models trend toward the NAM.
.LONG TERM...(Sunday night through Saturday)
Issued at 406 PM EDT SAT APR 11 2020
The main focus in the long-term remains the major winter storm for
Sunday night into Tuesday. As this dynamic system lifts across the
region, deepening as it traverse lower Michigan and Lake Huron, it
will bring a plethora of impacts to the Upper Peninsula. Travel
conditions will deteriorate rapidly Sunday night into Monday
morning, and linger throughout much of Monday into the overnight
hours. It is not out of the question that for a period of time on
Monday that some location could see blizzard conditions as north to
northwest winds ramp up. Snow is expected to be wet and dense, thus
snow removal will be very difficult and the combination of dense
snow and stronger winds on Monday will cause concerns for some tree
damage and power outages in spots. These winds will also allow large
waves to build along the Lake Superior shoreline over the tip of the
Keweenaw, and then near/east of Big Bay to Crisp Point. Significant
beach erosion may occur in spots and lakeshore flooding will be
possible!
The highly advertise system progged to bring widespread snow for
Sunday night into Monday is still on track. The majority of the
widespread heavy, dense snow does look to fall Sunday night into
Monday morning as the main 850mb low lifts across central Upper
Michigan, pumping in plenty of warm air advection. Additional large-
scale lift arrives from an intensifying vort max approaching,
coupled jet structure aloft, and deep area of frontogenesis
lingering overhead. Given the impressive synoptic scale lift, this
helps boost confidence in the higher QPF and snowfall totals. With
the surface low tracking over lower Michigan and Lake Huron, and the
850mb low up across far eastern Upper Michigan, northeast to north
upslope flow will aid in augmenting snowfall totals locally over the
higher terrain out west and in the north-central Sunday night/Monday
morning. It is not out of the question that we could get some lake-
enhancement as well off of Lake Superior, more so out west where
temperatures aloft will be a bit colder. Mid-day Monday into Tuesday
morning, the system quickly lifts northeast of the region. Expect
lake-enhanced snow to persist during Monday afternoon, mainly across
the west and northern parts of Upper Michigan as wrap around snow
continues to linger. Winds will also ramp up quickly on Monday, as
conditions as cold air advection favors deeper mixing and the
ability to tap into 30-40 knot winds aloft. Widespread winds of 35
to 45 mph look likely, with the strongest winds expected near the
Lake Superior shoreline. Monday night into Tuesday, the colder air
maintains it`s grip on the region so we should see lake-effect snow
showers persist across the WNW wind snow belts.
Did upgrade watches to warnings with the afternoon update as it
looks like at least 1 foot of snow will be possible for locations
out west and in the north-central. Areas across the higher terrain
could pick up more snow due to terrain enhancements. Menominee,
Delta, and northern schoolcraft counties look to be on the edge of
the rain/snow line and could go either way on p-type Sunday evening
as warmer air arrives, but they should switch back over to snow
Sunday night. Don`t have nearly as much ice as what was previously
in the forecast as the rain/snow transition zone where a wintry mix
of sleet, freezing rain, and snow looks to be fairly narrow. With
the potential for this wintry mix before switching over to
accumulating snow by Monday morning, did opt to issue an advisory
for those locations.
Did not spend much time looking further out into the week, but
persistent cold air advection continues to stream overhead.
Therefore, we should see the below-normal temperatures persist at
least through mid-week before we start to see temperatures modify.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 731 PM EDT SAT APR 11 2020
VFR conditions will prevail at KIWD/KCMX/KSAW into Sun morning.
Heading thru Sun aftn, snow will spread northward into the nw half
of Upper MI. As a result, expect conditions to fall to MVFR at
KIWD/KCMX in the late aftn to early evening hrs. Heavier snow is
more likely to impact KSAW, resulting in conditions falling to LIFR
by evening.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 438 PM EDT SAT APR 11 2020
Although a sfc trough will pass across Lake Superior tonight, winds
should remain mostly blo 20kt. Low pres will then organize over the
Southern Plains on Sun. This low will rapidly deepen as it crosses
the Great Lakes region Sun night/Mon morning. By Mon evening, deep
low pres will be located s of James Bay. This strong system will
likely bring gales to all off Lake Superior late Sun night through
Mon evening with storm force gusts also likely developing over the
east half Monday by late morning into Monday evening. A ridge of
high pressure will slowly build in behind this exiting low pressure
system on Tuesday as winds gradually diminish below 20 knots by
Tuesday evening.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Warning from 5 PM EDT /4 PM CDT/ Sunday to 2 AM EDT
/1 AM CDT/ Tuesday for MIZ001>003-009-084.
Winter Weather Advisory from 5 PM Sunday to 8 AM EDT Tuesday for
MIZ085.
Winter Storm Warning from 5 PM Sunday to 8 AM EDT Tuesday for
MIZ004>006.
Winter Storm Warning from 2 PM Sunday to 4 PM CDT Monday for
MIZ010-011.
Winter Weather Advisory from 3 PM EDT /2 PM CDT/ Sunday to 5 PM
EDT /4 PM CDT/ Monday for MIZ012-013.
Lake Superior...
Storm Watch from Monday morning through Monday evening for
LSZ249>251-266-267.
Gale Watch from late Sunday night through Monday evening for
LSZ162-240>248-263>265.
Lake Michigan...
Gale Watch from Monday morning through Monday evening for LMZ221-
248-250.
&&
$$
UPDATE...Rolfson
SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion...UPDATED
National Weather Service Springfield MO
911 PM CDT Sat Apr 11 2020
...MESOSCALE DISCUSSION...
Issued at 841 PM CDT Sat Apr 11 2020
Minor update this evening to add a marginal/limited threat for
some isolated hail up to the size of quarters, mainly across
southeast Kansas and western Missouri. 00z KSGF sounding measured
around 1000j/kg of most unstable CAPE (mainly elevated/above
700mb), 8.0C/km mid level lapse rates and 45kts of effective bulk
shear. A 45-50kt 850mb llj was in the process of developing across
eastern Oklahoma and was transporting abundant moisture into the
area.
Regional radar and satellite imagery continues to show a
developing area of showers and storms across Oklahoma and western
Arkansas. This area will continue to move northeast and into the
area overnight, especially after 06z and generally along and south
of I-44. Areas west of Springfield will have the highest
instability overnight therefore can`t rule out an isolated severe
storm with hail to the size of quarters in that area given the
sampled airmass this evening. Overall though the severe risk is
marginal overnight given the limited spatial threat area.
Southerly wind gusts will continue to be around 30 mph at times
tonight as the surface low continues to strengthen across western
Kansas. This will also keep temps from falling too much overnight
with most places remaining around 60.
00Z is just now coming in and will have to analyze how much
instability can be realized tomorrow afternoon ahead of the
incoming front. At this time, it looks like off and on morning
showers/storms may exit briefly by mid day or early afternoon. If
this occurs, then destabilization would allow for the development
of strong to severe storms by late afternoon and evening. 00z HRRR
and 00Z NamNest continue to indicate a broken line of strong to
severe storms tomorrow afternoon/evening with the strongest storms
closer to the Missouri/Arkansas state line. Confidence however is
still low on the strength of storms and potential impacts
tomorrow. Will continue to analyze the details tonight.
Lastly, surface winds Sunday night look strong as the surface low
exits the region and continues to deepen. Surface winds of
40-45mph look likely and a Wind Advisory will likely be needed for
portions of the area Sunday night.
&&
.SHORT TERM...(This evening through Monday morning)
A cluster of showers and thunderstorms impacted nearly all areas
of extreme southeast Kansas and the Missouri Ozarks today. This
convection has exited east and has allowed for a few hours of dry
and mild weather. As a matter of fact, temperatures were warming
quickly back into the 60s as skies cleared and wind gusts picked
up across the Osage Plains and western Ozarks.
For tonight, continued mild temperatures are expected, and most
areas should remain dry through the mid evening hours. Convection
then will spread into southern Missouri by late evening and
continue through the overnight period across south central
Missouri.
We can not rule out some convection northwest of Interstate 44
either, although chances are better to the south tonight. At this
time we are not expected severe weather tonight.
By tomorrow however, we could experience some organized
thunderstorms as an upper level storm system approaches from the
west.
Some of the HIRES models are indicating a high frequency of
thunderstorms within a decently sheared airmass. Instability
levels are uncertain for tomorrow, and could limit the strength of
thunderstorms. At this time we feel as though the most intense
storms will have the potential for producing large hail up to
quarters and damaging wind gusts.
We could also experience some localized flooding. Average storm
total precipitation will be around one inch, with pockets of
heavier amounts.
Colder air will spread into the region as thunderstorms are
exiting Sunday night into Monday morning. Overnight lows will fall
below freezing in many areas.
.LONG TERM...(Monday night through Saturday)
We will need to monitor for the risk of freezing conditions again
Tuesday and Wednesday mornings as readings fall into the upper 20s
and low 30s. Mainly dry conditions are expected Tuesday and
Wednesday with highs ranging from the upper 40s to the middle 50s.
By Thursday, models have been consistently showing the return of a
warm front becoming stationary either directly over or somewhere
near the Ozarks. Upper level flow will be zonal to slightly from
the northwest, which could trigger multiple rounds of showers and
thunderstorms from Thursday into next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 614 PM CDT Sat Apr 11 2020
Ceilings will likely remain VFR early in the period however
conditions are likely to drop into MVFR conditions after 06z as
rain moves into the area. Could be an isolated thunderstorm
however left as VCTS for now. Southerly winds around 20kts with
gusts around 30kts will continue through 06z as well.
After 06z, low level wind shear will develop at the sites.
Scattered showers and an isolated thunderstorm will be possible
with best chances closer to BBG. There will likely be a brief
break in the rain before another batch moves in Sunday afternoon
and evening. Thunderstorms are likely to occur Sunday evening.
Winds will then begin to switch to the west and then northwest at
the end of the period.
Just beyond this forecast period (00Z), winds will increase out
of the northwest with gusts around 40kts possible.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
MESOSCALE...Burchfield
SHORT TERM...Cramer
LONG TERM...Cramer
AVIATION...Burchfield
Area Forecast Discussion
National Weather Service San Diego CA
121 PM PDT Sat Apr 11 2020
.SYNOPSIS...
Dry and warmer weather today most areas, with isolated showers still
possible on the coastal mountain slopes and foothills. Another weak
trough will develop Sunday through Monday, lifting the moist air in
place along and west of our mountains, to generate some occasional,
light precipitation. The trough will move east Tuesday, setting us
up for some dry and warmer weather through Thursday. A more
unsettled pattern returns late next week for cooler conditions, more
clouds, and even the potential for more showers.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Skies were clear over a large part of SoCal this afternoon, except
for central San Diego County, where low clouds were widespread. the
added sunshine and lack of precipitation has boosted midday temps in
many areas from 6-10F over yesterdays readings. Surface pressure
gradients were beginning to increase onshore, but wind reports were
still mostly light. Clouds were thickening on the west slopes of the
San Diego Mts midday so it looks like more showers are possible
there this afternoon. Credit the recent HRRR model runs for
capturing this development. Even our local 06Z WRF model had a
couple of spots there this afternoon.
Other than a few light showers over the mts/deserts today, it was
dry for the first time in a while. No guarantees this will last
though as the atmospheric pattern over the Hemisphere becomes highly
amplified with a large trough over the continental U.S, and a ridge
over the EastPac. The trough will be large enough to drop sfc
pressure over the West, and create cyclonic flow aloft over CA. This
looks sufficient enough for widespread saturation over SoCal, which
in turn results in an abundance of clouds, and pockets of light
precip breaking out at times. Most, if not all of this will be along
and west of the mts, with the best chance on the coastal mtn slopes
and foothills where the moist air is forced upward due to the
onshore flow. Weak upper-level disturbances in the flow may enhance
the lift at times. POPs are low because this precip is likely to be
intermittent, scattered and light if and when it materializes.
It isn`t until sometime Tuesday that we exit this pattern, heights
rise, flow aloft becomes neutral to anticyclonic and atmospheric
moisture drops. The ridge off the coast never arrives, but has some
influence over SoCal, enough for a mostly clear and warmer interlude
during the midweek period. This will give a chance to get your
gardens planted ahead of another possible free watering.
Toward the end of next week, the pattern once again turns cyclonic
aloft as more troughing envelops the West. The medium range 12Z
model guidance suggests another rogue low pressure center will drop
south along the Coast, and turn inland somewhere over the
Southwest...an all-too-familiar pattern this year. There is no
consensus with timing or track of this feature yet. As a matter of
fact, uncertainty is higher than average, due to the spread and
clustering of the model`s ensemble members, but given the repetitive
nature of this pattern over the past Winter, it is hard to ignore.
At the very least, look for cooler and unsettled weather by next
weekend, with a chance of showers at some point.
&&
.AVIATION...
111930Z...Coast/Valleys/Mountains...Areas of SCT to locally BKN
clouds with bases 2000-3000 feet MSL will continue through this
afternoon. Widespread low clouds will move in this evening after 02Z
with bases around 1500-2500 feet, spreading 20+ miles inland
overnight, with higher terrain obscurations possible. Some afternoon
scatter out is possible Sunday, but most locations over and west of
the mountains will have persistent low clouds throughout the day.
Light showers may occur at times west of the mountains Sunday.
Deserts... FEW-SCT clouds at/above 7000 feet MSL will continue to
diminish this afternoon. Mostly clear with unrestricted vis this
afternoon through Sunday.
&&
.MARINE...
No hazardous marine weather is expected through Wednesday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...10
AVIATION/MARINE...Connolly
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Sunday)
Issued at 354 PM CDT Sat Apr 11 2020
Active weather dominates our short-term period as a strong system
impacts the region. The focus for this evening will be on timing and
placement of thunderstorm development and severity potential.
Attention then turns to hazards associated with an advancing cold
front set to move through the CWA tomorrow.
20Z water vapor shows a cut-off upper low spinning over the AZ/
Mexico border, and an upper trough digging into the northwestern
CONUS. At the surface, the ridge that was positioned over eastern
KS/western MO yesterday is now located over the Carolina coasts.
A deepening surface low was sitting over central KS at mid
afternoon. With the aid of southerly flow, dewpoints have steadily
increased today and are now in the low to mid 50s in eastern KS
and a dryline is evident on surface maps extending from the low,
southward into OK and TX. The warm and moistening atmosphere has
led to further destabilization of our airmass with afternoon CAPE
values ranging from 1000 J/kg near the NE state border to 2500
J/kg in south-central portions of KS. A low level jet is progged
to strengthen near and just south of I-70 after 00Z, which is also
when the HRRR and RAP, in agreement with some other convective
allowing models (CAMS), show thunderstorm initiation over central
and northeastern KS. Effective bulk shear values are forecast to
range from about 30 to 40 kts. The combination of shear and CAPE
could allow for some healthy updrafts leading to strong to severe
thunderstorms. The main concerns will be large hail and damaging
downburst wind. Storms should weaken after midnight but scattered
showers may linger into Sunday morning.
Attention then turns to the progression of a sharp cold front as it
marches across the area tomorrow. North-northwest winds quickly
increase behind the front and will become sustained between 25 and
35 mph with gusts to near 55 mph possible at times during the
afternoon. Thus, a High Wind Warning has been issued for the western
CWA with a Wind Advisory for the eastern half. Depending on the
timing of the front, another round of strong to severe storms will
be possible tomorrow afternoon just ahead of the boundary in
eastern KS. Stratiform light rain is expected behind the boundary
and efficient CAA will cause temperatures to plummet throughout
the day. A wintry mix of precipitation is even possible in
northern and north-central KS late in the day.
.LONG TERM...(Sunday night through Saturday)
Issued at 354 PM CDT Sat Apr 11 2020
Unseasonably cool temperatures will then settle in for the week
in the wake of this weekend`s system. Temps early Monday will
likely be in the upper 20s with afternoon temps only warming into
the 40s (feeling more like late February). Tuesday morning also
looks to be below freezing area-wide with locations in northern KS
experiencing sub-freezing conditions again Wednesday and Thursday
morning. While temperatures moderate a bit through the week, we
will remain below average with large scale troughing in place over
a wide swath of the country. A return to more seasonable
conditions can be expected next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 638 PM CDT Sat Apr 11 2020
Main concern will be convection through 06Z, primarily at TOP and
FOE. Short term models suggest development at TOP and FOE in the
01Z to 04Z time period. Isolated tsra may affect MHK after 01Z.
Forecast soundings suggest mvfr cigs developing after 06Z and
lowering to IFR after 10Z. A strong cold front will move through
the terminals in the 16Z to 19Z time period. Winds will shift to
the northwest and increase to around 22 kts with gusts up to
48 kts at MHK and around 37 kts at TOP and FOE.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM to 10 PM CDT Sunday for
KSZ011-012-023-024-026-038>040-054>056-058-059.
High Wind Warning from 10 AM to 10 PM CDT Sunday for
KSZ008>010-020>022-034>037.
&&
$$
SHORT TERM...Teefey
LONG TERM...Teefey
AVIATION...53
Area Forecast Discussion
National Weather Service Tulsa OK
923 PM CDT Sat Apr 11 2020
...UPDATE...
.DISCUSSION...
Area radars detecting scattered sub-severe convection across parts
of eastern OK into western AR, with additional storms across
southwest into central OK. This activity has moved off the
dryline, with the supercell near Lawton currently tracking due
east. Surface instability is essentially nil across the forecast
area, although an increasing low-level jet will allow storms to
fester through much of the night. Forecast soundings show around
1000-1200 J/Kg of elevated instability and 0-6km bulk shear should
be around 40-50kts, so a few severe storms will be possible. Large
hail will be the main threat.
Will lean toward the HRRR for the remainder of the night, and have
lowered PoPs across much of the area after 09Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 60 74 32 50 / 60 80 10 0
FSM 58 72 37 54 / 80 90 50 0
MLC 60 73 35 52 / 80 90 10 0
BVO 58 73 31 50 / 30 70 10 0
FYV 56 69 32 50 / 60 90 60 0
BYV 55 70 32 49 / 70 80 70 0
MKO 59 72 34 50 / 60 90 20 0
MIO 58 71 31 48 / 50 90 40 0
F10 60 73 34 50 / 70 80 10 0
HHW 61 73 38 55 / 50 90 10 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18