Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/19/20
Area Forecast Discussion
National Weather Service Bismarck ND
953 PM CDT Wed Mar 18 2020
.UPDATE...
Issued at 920 PM CDT Wed Mar 18 2020
We have issued a winter weather advisory for freezing drizzle or
light freezing rain and some light snow. This is for far southwest
and south central North Dakota, including the southern Jame River
Valley.
Currently, a shortwave is moving from southeast Montana into
southwest North Dakota. This is producing a nice band of light to
moderate snow, with probably a few bands of heavy snow, between
I-94 and Highway 2. Generally light snow along the International
Border. The heavier snow band correlate nicely with the 700 MB FG
forcing meeting up with the abundant moisture within the dendritic
growth layer. This area of snow should propagate east tonight.
Previous forecast amounts seemed reasonable, and match up pretty
darn well with the new mesoscale snow amounts just coming in.
Might adjust amounts up a little higher from around Garrison to
Stanley (3 to 4) instead of 2-3. Otherwise they look good.
After the aforementioned shortwave moves through this evening,
there is a nice dry layer aloft moves over southern North Dakota
into northern South Dakota. Models are not exact in where most of
the loss of ice aloft will end up, but they all indicate the ND/SD
border will be near the lower end, with much more ice aloft
remaining along and North of the Interstate. If model guidance is
right with the qpf late tonight into Thursday morning, we could
have maybe 5 hundredths of an inch of ice somewhere along the
ND/SD border (possibly more). That could be a little farther
north, or it may even end up south of the border, but felt there
was enough confidence to issue an advisory. The RAP show better
potential for ice accum south of the border, while the NAM has the
potential for ice accum almost up to the Interstate. Also from
the Border north, we expect road temperatures will drop below
freezing, allowing ice accumulation on untreated surface. In
addition, there has been low visibility from Oakes to Hettinger
all evening, which will deposit and freeze on roads. The Hettinger
ASOS reported a hundredth of an inch of ice accum this past hour.
Overall, we felt there was enough of a signal to issue the
advisory.
Hazard should already be out, remaining text products will be out
shortly.
UPDATE Issued at 543 PM CDT Wed Mar 18 2020
For this update we added some fog, mainly west and south.
Dickinson remains in dense fog, and Oakes has dropped to a quarter
mile or less, but most areas are in the 1-3sm range. Will monitor
to see if dense fog expands, but for now we`ll go with areas of
fog. Widespread light to moderate snow is also breaking out across
eastern Montana into western North Dakota. This could also temper
the fog a bit. Expanded likely and categorical pops over most of
the west central and extending into central ND around Beulah,
Garrison and Max a little earlier than previously forecast.
Otherwise no changes to the going forecast.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 216 PM CDT Wed Mar 18 2020
Highlights for the short term include accumulating snowfall of
between 2 and 4 inches near/along and north of Highway 2. Farther
south a wintry mix with lesser amounts. Expecting snowfall of up
to one inch along and south of Interstate 94 tonight along with a
chance of light freezing drizzle later tonight.
A northern stream shortwave trough will swing through tonight,
atop a cold frontal boundary that will slowly sag south overnight.
Snow will be most pronounced north of Interstate 94 to the northern
border, with a wintry mix south. Latest water vapor imagery shows
a large area of dry air in the mid/upper levels via the southern
stream now over Wyoming and Colorado. Our top-down approach shows
this drying streaming into southwest North Dakota at 00z Thursday,
then expanding into far south central and portions of the James
River Valley 06z-12z. A cold front now over northern North Dakota
will begin to slowly shift south overnight. As mentioned above, as
low level convergence and frontogenetical forcing increase
overnight, expect a mix of snow and light freezing drizzle south,
with snow north. A little concerned about the far south overnight
where freezing precipitation could last longer with the cold
front/cold air advection not reaching the south until closer to
12z Thursday. Think road/surface temperatures may remain above
freezing for a good portion of the night. Will alert the evening
shift to monitor this potential. Otherwise, the NAM/RAP/GFS BUFKIT
soundings also show a loss of moisture/ice in the dendritic
growth zone (-10C to -30C) portions of south central and the James
River Valley after 06z. Thinking is we will have light snowfall
prior to losing ice aloft in the majority of the area, except in
the far south. This will be followed by light freezing drizzle
late. After collaboration with neighboring offices, we have
decided to continue with the Special Weather Statement reiterating
a heightened awareness for snow north and a wintry mix south. The
surface cold front doesn`t actually shift through Bismarck until
09z-12z Thursday. Precipitation threat ends by 15z for all but the
far southern James River Valley. Gusty northerly winds begin to
initiate late tonight through Thursday. Could be patchy blowing
snow north. A wind advisory in the far southern James River Valley
looks possible Thursday afternoon and will let subsequent shifts
analyze this with the latest data.
.LONG TERM...(Thursday night through Wednesday)
Issued at 216 PM CDT Wed Mar 18 2020
Tight pressure gradient in place Thursday evening with a 1040mb
surface high over southern Saskatchewan and a 994mb low located in
Oklahoma. In between, strong northerly winds especially over the
James River Valley will gradually subside overnight as the surface
highs nudges into northern North Dakota by 12z Friday. Expect
lighter winds Friday with plenty of sunshine as a mid level ridge
propagates across western and central North Dakota. It will remain
cold with high temperatures well below normal. Highs will range
between 15F and 27F. Another compact upper low/shortwave trough
slides from central and southern Saskatchewan into central North
Dakota Saturday with a chance of light snow. This exits Saturday
night followed by a more progressive zonal flow with another system
expected Tuesday through Wednesday. High temperatures will rebound
back into the 30s north and east, to the 40s elsewhere Sunday
through Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 920 PM CDT Wed Mar 18 2020
Snow and areas of light freezing rain/drizzle will continue to
increase this evening and overnight. Expecting snow across the
northern terminals of KXWA and KMOT with IFR/LIFR cigs and vsbys.
Farther south, KBIS/KJMS, there will likely be a period of light
snow, but then possibly transition to light freezing rain or drizzle
between 06z and 12z Thursday. IFR/LIFR cigs/vsbys expected across
the south through the period. IFR-LIFR visibilities at KDIK and may
also spread into KBIS and KJMS through the overnight hours. Gusty
northerly winds develop to 25kt after 06z Thursday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 PM CDT /noon MDT/ Thursday for
NDZ040>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...KS
AVIATION...TWH
Area Forecast Discussion
National Weather Service Charleston SC
855 PM EDT Wed Mar 18 2020
.SYNOPSIS...
A warm front will move north through the area tonight as high
pressure shifts offshore. A cold front will move through the
area this weekend, followed by several disturbances through the
middle of next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Quick update to adjust the POPS/Weather. A band of showers to
our south is maintaining it`s intensity as it approaches our
area. The latest HRRR generally shows them dissipating as they
reach our border. But it didn`t appear to initialize well,
barely showing the showers where they are currently. With that
in mind, we raised the POPs to slight chance along our GA
counties for roughly the next 2-3 hours.
A weak warm front will lift north late this evening with mild,
humid conditions to continue overnight. Meanwhile weak NVA will
overspread our inland zones. The concern is the fog potential.
It is likely to develop late this evening or early Thu morning,
potentially becoming dense. Models vary a bit on the start time,
but most seem to paint a general picture of where the worst
conditions should be and the forecast reflects this.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
No major weather impacts expected during the short term. Surface
high pressure will be offshore Thursday into Friday. Bringing dry
weather and unseasonably hot temperatures. Several records are at
risk of being broken. By Saturday an approaching cold front could
bring showers to our area. Though, we only have chance POPs for now.
The risk of thunderstorms is very low and even the rainfall
potential does not look to be too impressive. Additionally,
condition over the coastal waters could lead to the formation of
sea fog. If any does form, it could bring impacts to the coastal
counties.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Low confidence this period. A weak cold front should push through
Saturday night but after that the forecast becomes much more
uncertain. We trended the forecast toward the WPC guidance which
leans toward the GFS model, with decent rain chances through Monday
as deep moisture and upper level disturbances move through, then
warmer and drier conditions into mid week. Temperatures should
generally be near or above normal.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
00Z TAFs: Both TAFs start out VFR. A warm front is forecasted to
lift north tonight, causing moisture to increase. MOS Guidance
and models paint a mixed picture, from minimal impacts for a few
hours to many hours of LIFR. We leaned towards the SREF, HREF,
and some of the MOS. The result is MVFR forming around midnight,
with solid IFR late tonight. There is concern the timing may be
off, so amendments may be needed before the the 06Z TAFs are
issued. VFR should return around 15Z, with winds increasing by
Thursday afternoon.
Extended Aviation Outlook: Mainly VFR Friday. Fronts could
bring periodic flight restrictions Saturday through Monday.
&&
.MARINE...
The main issue is the fog potential overnight following a warm
front lifting north. Most guidance indicates at least patchy fog
developing over the nearshore waters within 15 NM from the
coast. Given dewpoints in the mid-60s and decreasing wind speeds
overnight, dense sea fog seems fairly likely in some areas.
High pressure will be offshore Friday. A cold front will move
through the area on Saturday. Several disturbances are expected
to move across the region starting Sunday and continuing well
into next week. Wind and seas are expected to be below advisory
levels Friday and Saturday. Small Craft Advisories could be
needed for portions of the waters Sunday night into Monday.
Additionally, southerly winds ushering higher dew points over
the cooler nearshore waters could lead to sea fog into Saturday.
&&
.CLIMATE...
Record highs for March 19:
KCHS: 85/last set in 2012
KSAV: 89/last set in 2011
KCXM: 84/1963
Record high mins for March 19:
KCHS: 65/1986
KSAV: 65/last set in 2008
KCXM: 65/last set in 1963
Record highs for March 20:
KCHS: 88/1982
KSAV: 90/1907
KCXM: 90/1907
Record high mins for March 20:
KCHS: 66/1945
KSAV: 69/1945
KCXM: 68/1945
Record highs for March 21:
KCHS: 90/2017
KSAV: 91/1935
KCXM: 92/1935
Record high mins for March 21:
KCHS: 64/last set in 1989
KSAV: 69/1927
KCXM: 68/1927
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...
SHORT TERM...MS
LONG TERM...RJB
AVIATION...
MARINE...JRL/MS
CLIMATE...
Area Forecast Discussion
National Weather Service Cheyenne WY
852 PM MDT Wed Mar 18 2020
.UPDATE...
Issued at 835 PM MDT Wed Mar 18 2020
Updated forecast through tonight and removed most of the Tstorm
wording as thundershowers have dissipated across far southeast
Wyoming this evening. Additional bands of rainfall expected to
continue tonight with light snow above 7500 feet. These snow
levels will gradually lower to the valley floors/high plains
after midnight tonight as surface cyclogenesis occurs across the
eastern/northeastern plains of Colorado. Next round of updates
will likely deal with the change over time to snow.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 320 PM MDT Wed Mar 18 2020
Storm still looks on track to produce major impacts across
southeast Wyoming and Nebraska Panhandle the next 24 to 36 hours.
Currently...Water vapor imagery showing our closed upper level low
over southern California this afternoon. Looks like its just about
ready to eject northeastward as a 130kt jet max rounds the base of
the longwave trough. Closer to home...stalled out surface boundary
lays from Sidney to Laramie to Casper and then northwest into
western Montana. Stratus persists in the Panhandle with the
upsloping east and southeast flow. We are starting to see
convective development on KCYS radar...mainly over Albany County.
Did get a few lightning strikes over north central Colorado
earlier...so the call for isolated thunderstorms was good for this
afternoon.
Precip expected to become widespread this evening into early
Thursday. HRRR and Hires short term guidance showing a solid band
of precipitation developing across the Summit into the northern
Panhandle shortly after 01/02Z this evening. Certainly looks
convective in nature...so could have some early evening
thunderstorms.
Most precip tonight expected to fall as liquid with the exception
of the Snowy and Sierra Madre Range that should see snow. One area
of concern would be the northern Panhandle into Niobrara County
tonight as forecast soundings showing possibility of freezing
rain/drizzle up there. Getting fairly high ice accumulations...on
the order of .1 to .2 inches of accumulation before it turns over
to snow.
After coordinating with our office to the east...decided to start
blizzard warnings earlier to match up with them. As a
result...decided to cancel the winter weather advisories as most
of the freezing precip will start at the beginning of the 12Z
start time of the Blizzard. Did break out the northern Panhandle
and Converse/Niobrara Counties to reflect the freezing
rain/drizzle in the blizzard warning.
GFS coming in stronger on winds...showing 40-45kts over the
Panhandle at 850mb and 45-50kts over the Summit at 700mb Thursday
morning. Area of most concern for blizzard conditions looks to
along and south of a line from Alliance to Buford. Heaviest QPF
totals are in this locations as well as the stronger winds. Though
winds are stronger than previous forecast over Converse County
with 750 and 800mb winds 35-40kts.
Precip begins to ease up after 06Z Friday...so we may be able to
cancel the Blizzard Warnings earlier. We will see how it goes.
.LONG TERM...(Saturday through Wednesday)
Issued at 320 PM MDT Wed Mar 18 2020
Overall looks like it will be mild and somewhat unsettled across
the CWA through the period as several weak disturbances move
across the area from time to time. Most pcpn will fall over the
higher mtns aided by orographics with more isolated rain and snow
showers over the plains, mainly in the Tuesday/Weds time period.
Temperatures should be close to seasonal averages, warmest Monday
and Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday afternoon)
Issued at 520 PM MDT Wed Mar 18 2020
Expect conditions to deteriorate to widespread IFR/LIFR conditions
tonight as a cold front drops across the area and winds turn upslope
behind it. Sctd showers with a few storms over se Wy early this
evening then areas of rain and snow developing later on across much
of the area. Bad conditions Thursday with winds becoming strong and
gusty especially over the plains, along with snow continuing to
produce widespread IFR/LIFR conditions.
&&
.FIRE WEATHER...
Issued at 320 PM MDT Wed Mar 18 2020
Major winter storm to begin impacting the area tonight that will
continue through Friday morning. This is due to a slow moving low
pressure system that tracks into northeast Colorado and eventually
into eastern Nebraska. Most locations expected to see significant
snowfall. Colder temperatures and high humidity through the next 7
days...so fire weather concerns will be minimal. Another chance
for rain and snow returns Tuesday next week that will persist
into Wednesday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Blizzard Warning from 6 AM Thursday to 6 AM MDT Friday for
WYZ101-102-107-108-117>119.
Winter Weather Advisory from 3 AM Thursday to 6 AM MDT Friday
for WYZ103>106-109-111-113-115.
Blizzard Warning from 3 AM Thursday to 6 AM MDT Friday for
WYZ110-116.
Winter Storm Warning until 6 PM MDT Friday for WYZ114.
Winter Weather Advisory until 6 PM MDT Friday for WYZ112.
NE...Blizzard Warning from 6 AM Thursday to 6 AM MDT Friday for
NEZ002-003-019>021-054-055-095-096.
&&
$$
UPDATE...TJT
SHORT TERM...GCC
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...GCC
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1029 PM CDT Wed Mar 18 2020
.Discussion...
Issued at 252 PM CDT WED MAR 18 2020
The forecast focus through tomorrow will be for thunderstorms with
potential for strong storms tonight and tomorrow morning and severe
thunderstorms Thursday afternoon/evening. Minor flooding and flash
flooding is possible Thursday. Gusty winds Thursday afternoon
through Friday morning. Much colder temperatures through the weekend.
Key Messages...
1. Showers and thunderstorms expected after midnight through
Thursday morning, some of these storms could be strong with small
hail and strong winds the main threats. Localized minor flooding is
again possible with up to an inch of rain possible for some areas.
2. Severe weather threat Thursday afternoon/evening, with low topped
supercells possible with hail, strong winds, and a brief tornado
possible.
3. Strong winds ahead and behind cold front Thursday afternoon
through Friday morning wind advisories possible.
4. Much colder Friday morning through the weekend with lows in the
20s with potential for a hard freeze each morning.
Discussion...
Satellite shows the area covered in clouds with some small breaks in
the overcast. Rain is moving out of the area as a broad ridge moves
over the area.
Tonight and Thursday: Surface warm front will be located over
central Missouri with areas of light drizzle or rain developing
around midnight. A shortwave trough will approach the area
supporting an area of showers and thunderstorms. MUCAPE from 500 to
near 1000 J/kg. Also strong shear with 40 to 50 knots. SPC has
western edge of area in marginal risk, so we expect strong storms
early Thursday morning between roughly 4 AM until around mid-morning
Thursday. Small hail and strong winds will be main threats.
Additionally PW`s will be 1.25 to 1.50" so localized heavy rain
could produce minor flooding or flash flooding.
Thursday afternoon: A substantial mid-level dry slot will cut into
the region in the wake of morning storms. The latest guidance
continues to suggest a trend of stronger destabilization in the wake
of morning convection ahead of a dryline, creating a conducive
environment for severe weather. A large chunk of the CWA remains
underneath the core of the upper jet, not particularity supportive
of strong ascent. However, the left front quad and approach of
strong vorticity advection may create a sweet spot ahead of the
approaching dryline Thursday afternoon to generate a string of
isolated/widely scattered convection from SE Nebraska into northeast
Kansas by mid-afternoon, quickly moving east- northeastward into
northwest/northern Missouri and Iowa through the remainder of the
afternoon and early evening. Effective shear profiles and EL heights
(near 30kft) would suggest the potential for a few low-topped
supercells in an environment of 1000-1500 J/Kg SBCAPE. The primary
concern with these would be large hail up to ping-pong ball and
perhaps a brief spinup. Across the remainder of the CWA, the
probability is lower that convection develops, and therefore the
overall severe risk lower. Expect a breezy day with southerly winds
gusting to 35-40 mph during the afternoon. Some concerns with a wind
advisory Thursday afternoon, but current HRRR shows max gusts in low
40s so not enough confidence to pull trigger on this, will let night
shift reevaluate this. The sun may finally make an appearance,
helping afternoon temperatures soar into the 70s, with dewpoints in
the upper 50s to lower 60s.
Thursday night/Friday: Storms will move out before midnight with
strong winds. Models showing tight pressure gradient with cold air
advection so wind gusts of 40 to 45 mph are possible with a wind
advisory also possible. Otherwise it will be much cooler with highs
on Friday struggling to get out of the 30s. More sunshine expected
which will help to cheer spirits after clouds most of the week. Hard
freeze likely Friday through Sunday morning with lows in the 20s.
&&
.Aviation...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1029 PM CDT WED MAR 18 2020
Low clouds ranging from MVFR to LIFR are spreading across the
terminals late tonight, and will continue to prevail across the
region as a strong low level jet noses in early Thursday morning.
As the low level jet noses in it will develop thunderstorms early
in the morning along with low level wind shear. Expect
thunderstorms to lift northeast quickly, with showers through the
morning. As showers clear out strong and gusty southerly winds
will then prevail through the later half of the Thursday morning
through the afternoon. Thunderstorm redevelopment is possible
Thursday afternoon, but currently storms are expected to be east
of the terminals.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Christensen
Aviation...Cutter
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1027 PM CDT Wed Mar 18 2020
.UPDATE...
As of 03Z, radar is quiet across south central TX and satellite
imagery indicates rather benign conditions upstream over northern
Mexico as well, with just a few patchy weak returns. CAMs are still
indicating elevated shower and storm development may still be able to
occur above a capping inversion that just doesn`t want to erode. RAP
analysis shows a subtle upper level shortwave upstream that may be
able to provide the necessary ingredients, but thus far haven`t seen
the response in satellite imagery one would expect. Have slowed the
progression of POPs to account for these trends. Am tempted to lower
them as well, as I`m not entirely convinced the cap won`t hold strong
and preclude any more than widely scattered shower and storm
development overnight. Given this late timing, instability will
dwindle somewhat but MLCAPE should remain in the 1000-1500 J/kg range
with ample deep layer shear should any storms be able to fire as the
shortwave moves into the better thermodynamics. Thinking that an
isolated strong storm cannot be completely ruled out, with a large
hail or gusty wind report possible but increasingly unlikely as the
night progresses.
&&
.PREV DISCUSSION... /ISSUED 624 PM CDT Wed Mar 18 2020/
AVIATION...
VFR conditions will continue at all sites into tonight. MVFR should
return by 06z along the I-35 corridor and 10Z at DRT and will stick
around through most of the day on Thursday before VFR conditions
return late in the afternoon. There is a chance that the San Antonio
terminals briefly drop to IFR around sunrise, with a better chance
for IFR cigs for a few hours at DRT.
Showers and thunderstorms are still expected to potentially impact
DRT, likely in the 02-04Z time frame. This activity will gradually
diminish, and the dying complex of showers should be across the I-35
corridor between 06z and 12z with VCSH remaining in the forecast at
AUS/SAT/SSF that may later be upgraded to -shra. Thunder is not
expected but cannot be completely ruled out at the I-35 sites in the
AM.
PREV DISCUSSION... /ISSUED 240 PM CDT Wed Mar 18 2020/
SHORT TERM (Tonight through Thursday Night)...
As of this afternoon the long mentioned upper level low pressure
system is just off the coast of Baja California and will be moving
east through the day today. The upper low will traverse the SW
United States this evening into Thursday. As it does it, and another
shortwave will move across Texas in the southwest flow aloft. This,
combined with the west Texas dryline, orographic lifting along the
mountains of Mexico, and daytime heating will spark off storms
across West Texas. These storms will move across the Rio Grande
Plains this evening and then towards the I-35 corridor after
midnight. Convective allowing models spark off these storms around 8-
9 pm, then push them across areas like Rocksprings and Uvalde by
midnight. A general weakening trend is expected further east, but
showers and a few thunderstorms are possible along the I-35 corridor
in the early morning pre-dawn hours. Two important caveats on
confidence here: 1) model soundings from the NAM show a capped (warm
air inversion) atmosphere across the Rio Grande Plains which may
limit overall convection, and 2) the models have been very bullish
the last few days on coverage and intensity of storms across the Rio
Grande. While there have been storms they have tended to be more
isolated and weaken quicker as they head east overnight. These two
factors could limit overall convection today. That said anything
that does form will be in a favorable atmospheric environment for
strong to severe storms and heavy rainfall with CAPE of 1200 j/kg,
around 60 knots of shear, and precipitable water values of 1.5
inches or more. Because of this the slight risk has been
maintained by SPC across the Rio Grande with the I-35 corridor now
included in the marginal risk. The threat will initially be hail
with any isolated storms, but then transition to more of a wind
threat as the complex of storms form.
Thursday itself should be mostly dry as the upper low heads east and
warm weather still stick around one more day. Flow though remains
southwesterly in the mid-levels and one more upper level shortwave
will come across late Thursday night into Friday morning. Timing
will be important here as a more polar surface front will be
dropping south across the state. Storms should form again late
Thursday night and head to the northeast. If the warm sector
maintains itself Thursday night another round of strong to severe
storms are possible. If the front arrives it could undercut the
storms and turn the threat Thursday night into Friday morning more
into a heavy rain and potentially minor flooding threat. The 12z
synoptic models pushed back the arrival until around sunrise Friday
at the earliest. With the juxtaposition of the front and upper level
disturbance Thursday night into Friday presents the best opportunity
for widespread rain that we have seen all week.
LONG TERM (Friday through Wednesday)...
The front will continue to move to the south Friday and move away
from our southern area during the day. Showers and thunderstorms will
continue with higher chances before noon and then ending from
northwest to southeast. The front will stall across South Texas.
Isentropic flow across the boundary will bring rain chances back to
the north Saturday. Saturday night and Sunday the upper level trough
will move across North Texas bringing one more chance for showers and
isolated thunderstorms.
Temperatures behind the front will drop significantly. High
temperatures will be around 15 degrees lower than Thursday. Lows
Saturday will be 10 to 15 degrees lower than Friday morning.
Monday an upper level ridge will build over the Southern Plains
bringing dry weather which will continue through the end of the
period. Temperatures will warm through the first part of next week
reaching well above normal by Tuesday with highs in the 80s and lower
90s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 68 80 59 64 46 / 50 30 80 90 10
Austin Bergstrom Intl Airport 68 81 58 65 46 / 60 30 80 90 10
New Braunfels Muni Airport 67 81 60 66 47 / 50 20 80 90 10
Burnet Muni Airport 66 79 55 59 43 / 50 20 80 80 -
Del Rio Intl Airport 66 85 60 72 51 / 60 0 60 20 -
Georgetown Muni Airport 67 80 56 61 44 / 50 30 80 90 10
Hondo Muni Airport 67 83 59 68 48 / 50 10 80 70 10
San Marcos Muni Airport 67 81 58 66 46 / 50 30 80 90 10
La Grange - Fayette Regional 70 81 63 69 49 / 40 30 70 90 20
San Antonio Intl Airport 68 82 60 66 49 / 50 20 80 90 10
Stinson Muni Airport 69 84 62 68 51 / 50 20 80 90 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...KCW
Long-Term...Runyen
Area Forecast Discussion
National Weather Service Goodland KS
835 PM MDT Wed Mar 18 2020
.UPDATE...
Issued at 835 PM MDT Wed Mar 18 2020
McCook, Oberlin and Colby are reporting dense fog with
visibilities of one quarter mile. The latest visibility guidance
remains in good agreement with thinking in the 6PM update. Have
gone ahead and issued a Dense Fog Advisory for locations generally
along and north of the interstate. Its possible that the counties
along the interstate will get out of the fog after midnight as a
warm front lifts north. Should that happen the advisory will
likely be cancelled for those counties. For areas along and north
of highway 36 confidence is higher that dense fog will continue
through Thursday morning.
I`ve also upped the winds a bit for late Thursday afternoon. Wind
gusts to 55 mph are currently expected. Wouldnt be surprised if
we see a few gusts higher than 60 mph. Will let the midnight shift
get another look at 00z and 06z data before making a decision on
a potential High Wind Watch or Warning.
UPDATE Issued at 600 PM MDT Wed Mar 18 2020
Tonight...looking at 12z and 18z data current thinking is a warm
front south of the interstate will remain in place this evening
before slowly lifting north of the interstate by midnight. Fog is
expected to redevelop north of the warm front and likely become
widespread and dense. After midnight dense fog is likely mainly
closer to the Nebraska Kansas border area. Will watch trends for
another hour or so before possibly issuing a Dense Fog Advisory.
May need to add a mention of showers/thunderstorms late this
evening south of the interstate as a mid level weather disturbance
moves in from New Mexico. This feature lifts northeast north of
the interstate shortly early Thursday morning.
Thursday...much of the area looks precipitation free in the
morning with a continued threat of locally dense fog from Yuma
county east through extreme southwest Nebraska. For the early
afternoon hours wraparound precipitation enters the northwest 1/3
or so of the area along and behind a cold front. By late
afternoon the best 850-500mb moisture favors highest chance of
precipitation across the northwest 1/2 to 2/3 of the area. Right
now its possible that the pop forecast may be too fast in bringing
precipitation into the area. Will see what 00z models say.
Another concern is the wind. 18z NAM model showing 3 hour pressure
rises of 10-14mb from McCook to Tribune west. This seems to be
represented well in the latest LAMP guidance which shows sustained
winds in the mid 30kt range. Given the very strong 3 hour pressure
rises I would be shocked to see wind gusts in excess of 60 mph.
This is supported by the HRRR which has a few gusts to 65 mph.
A High Wind Watch or Warning may be needed for locations outside
the Winter Weather Advisory.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 237 PM MDT Wed Mar 18 2020
Satellite and 500 mb RAP analysis showed southwest flow continuing
over the High Plains today as a closed low moved ashore south of
California. Cloud cover thickened ahead of the low and pushed into
the region from the southwest this afternoon. Light winds under 10
mph were observed through the morning. Winds have begun to increase
this afternoon. At 2 PM MT, temperatures ranged in the upper 40s to
upper 50s.
Very complex weather is anticipated over the next 48 hours. During
this time, our system south of California is expected to track
across the desert southwest and towards the region through Thursday.
Tonight: We could see some patchy dense fog redevelop north of
Interstate 70 this evening, particularly in southwest Nebraska and
northwest Kansas. Meanwhile, chances for rain increase across the
region from northwest to southeast, with a few rumbles of thunder
possible.
Thursday: Rain chances persist through Thursday, with a few
thunderstorms possible (particularly north of I-70). Rain will start
to transition to snow mid to late afternoon for the northwestern
portions of the area as precipitation steadily pushes southeast. As
this changeover occurs, southerly winds will shift to the north and
strengthen. Sustained winds of 30 to 40 mph, with gusts up to 50 mph
are forecast. This combined with falling snow will likely reduce
visibilities (for locations where the rain has switched to snow).
Fire weather sidenote: For Thursday afternoon, locations southeast
of a line from Hill City to Tribune will see relative humidities as
low as 30 percent. In addition, wind will be shifting from south to
north around 25 to 35 mph, producing near-critical fire weather
conditions for this southeastern portion of the region. Onset of
precipitation in this area should be later in the day, so thought
these conditions were worth a mention.
Thursday night: Snow will linger through the evening for most of the
region, with blowing snow possible as well. Gusty north winds
continue into the evening, gradually decreasing. Total snow amounts
are roughly 1 to 3 inches northwest of a line from Flagler, Colorado
to Culbertson, Nebraska with a trace to 1 inch for areas southeast
of that line. Snowfall should end by or around midnight. However,
breezy winds may still blow around loose snow before sunrise.
Confidence: Many variables make this a difficult forecast. Problems
crop up due to the timing of rain transitioning to snow and how this
will coincide with the timeframe of the strong winds. This makes it
tough to determine how low visibilities may get and for how long.
Additionally, the track of this system could change snow amounts
(higher or even lower). Because of these factors, decided a Winter
Weather Advisory for the northwestern counties was most appropriate
at this time.
Temperatures: Will focus on low temperatures first since those will
be most impactful. Those with agricultural/ranch interests should
monitor the temperatures for the next few nights. One more warm
night, upper 30s to upper 40s, is forecast tonight before a drop
Thursday night. Temperatures will fall into the teens after midnight
Thursday night and persist into early Friday morning, with wind
chills near zero degrees. Those involved in calving season may need
to take precautions. Lastly, there will be a spread in high
temperatures on Thursday, ranging from the low 40s in Yuma County to
the low 60s in Graham County.
.LONG TERM...(Friday through Wednesday)
Issued at 224 PM MDT Wed Mar 18 2020
For the extended period the models are showing a mostly zonal flow
aloft for the period. Embedded within this flow will be shortwave
troughs transiting through the region. On the Surface, a ridge
extends from the high pressure center located over the Canada/US
border. As we move later into the period, a trough will develop over
the Front range as the high pressure center, and the ridge extended
from it, will move eastward into the northeast US. Towards the end
of the period a low pressure system is expected to develop over the
Central High Plains along with its associated fronts.
Expect Dry and cold conditions on Friday with the highs reaching the
upper 30s and the overnight lows dropping into the middle to upper
teens.
Saturday dry conditions will continue with the highs warming into
the lower 50s and lows in the middle to upper teens.
For the rest of the period afternoon highs will reach into the 60s
with overnight lows dropping into the middle to lower 30s. However,
chance for precipitation returns with the shortwaves moving through
the region. Rain will be possible for most areas, with a few areas
potentially seeing snow/rain mixed during the overnight hours.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 520 PM MDT Wed Mar 18 2020
A surface low is located near the Palmer Divide with a warm front
extending east to the south of Interstate 70. Low level moisture
remains abundant to the north of the front and will quickly
produce widespread fog and some drizzle this evening before
lifting north of the interstate between midnight and sunrise
Thursday morning. Sub vfr conditions are expected in Goodland from
around 03z-06z with a brief period of dense fog possible. For KMCK
sub vfr conditions will continue through this time with dense fog
possible.
From 12z-18z the surface low is expected to be near KGLD with
variable winds around 12kts expected and vfr conditions. For KMCK
the warm front will be in the vicinity of the terminal by 18z and
vfr conditions are possible if the hrrr models are correct. Right
now I have sub vfr conditions with an east-northeast wind near
15kts.
From 18z-00z the surface low is expected to be over central Kansas
with a cold front moving through both terminals. KGLD will see
north winds gusting over 40kts with sub vfr conditions returning.
KMCK will see north winds gusting to around 40kts with sub vfr
conditions expected. Right now precipitation type will be rain but
we cant rule out some light snow if the colder air arrives just an
hour or two faster than currently expected.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Dense Fog Advisory until noon MDT /1 PM CDT/ Thursday for
KSZ001>004-013>015.
Winter Weather Advisory from 1 PM Thursday to 7 AM CDT Friday
for KSZ001.
CO...Dense Fog Advisory until noon MDT Thursday for COZ090.
Winter Weather Advisory from noon Thursday to 6 AM MDT Friday
for COZ090-091.
NE...Dense Fog Advisory until noon MDT /1 PM CDT/ Thursday for
NEZ079>081.
Winter Weather Advisory from noon MDT /1 PM CDT/ Thursday to 6
AM MDT /7 AM CDT/ Friday for NEZ079-080.
&&
$$
UPDATE...99
SHORT TERM...JBH
LONG TERM...BW
AVIATION...99
Area Forecast Discussion
National Weather Service Gray ME
1038 PM EDT Wed Mar 18 2020
.SYNOPSIS...
Weak low pressure passing to our south on Thursday will bring light
snow accumulations across southwestern New Hampshire before
warmer air changes precipitation to all rain by later Thursday.
Unseasonably mild air arrives for Friday ahead of an approaching
cold front. High pressure with colder and drier air arrives for
the weekend through the start of next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Update...
Have updated the forecast based on current conditions and latest
mesoscale models. Clouds continue to thicken from the next
system with mid and high level moisture advecting into the
region early tonight. The latest HRRR is in good agreement with
our current expectations with snow entering southern New
Hampshire between 09Z and 12Z with some rain in southern New
Hampshire and along and near the coastline. Have pushed back
the chance for precipitation by a couple hours to match this
scenario.
Made some minor adjustments to the temperatures and dew points.
Prev Disc...After a warm and sunny day, high pressure shifts
east tonight with increasing onshore flow. Between increasing
dew points and increasing clouds, temperatures will be warmer
tonight than previous nights, lowering into the 20s (north) to
the mid-30s (coast and southern interior).
A convective wave presently (as of this afternoon) over the Ohio
valley tracks ENEward with shortwave energy, arriving in New
England late tonight into Thursday morning. There has been a
steady southward trend in model guidance with this feature due
to the upstream convective influence, so expect max QPF 0.3-0.5"
to focus over southern zones during the morning, if not slide a
little further south out of the area. Temperature profiles support
snow as the wave comes into the area which may have impacts on
the morning commute. Although accumulations will be fairly
light, generally around an inch max, some pockets of moderate
snowfall rates may develop which would lead to reduced visibility
and a few slick spots during the morning commute. Southwest NH
stands the best chance for accumulation.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Precipitation associated with a crossing shortwave transitions
to rain everywhere except for peaks and ridges over the north by
noon as temperatures rise above freezing. Given widespread cloud
coverage south and east of the mountains plus onshore flow,
afternoon temperatures will be fairly uniform across the
forecast area, topping out in the upper-30s to mid-40`s.
Remnant low pressure lingers off the southern New England coast
which keeps onshore flow and light rain chances over the coastal
plain for most of the day into the evening. Interestingly, a low
level jet forms on the northern side of the remnant low as it
moves NEward into and across the Gulf of Maine Thursday evening.
Although cool sea surface temperatures keep the bulk of winds
elevated, a few gusts in the 20-25 kt range are possible along
the coast.
Looking at the broader picture, zonal flow aloft over the
northeast breaks down through the short term period with
increasing southwesterly flow as a long wave trough approaches
from the west, allowing an increasingly humid airmass to form
locally. Increasing baroclinicity in the absence of broad
synoptic forcing keeps showery conditions going over the region
Thursday night with greatest precipitation chances in the
mountains, aided by SE-facing upslope flow.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The 500 mb pattern across North America will continue to
feature a -PNA with a broad upper ridge over the South East and
trough in the West. Multiple waves will act to knock down the
South East ridge into next week with 500 mb pattern
transitioning to more zonal flow across the CONUS by the middle
of next week.
At surface low pressure will pass to our NW Friday driving a warm
front through the area with an unseasonably warm and moisture rich
airmass moving into New England. Temperatures will be in excess of
20 degrees above normal with PWATs approaching +5 sigma of average.
This will translate to highs Friday approaching 70 across southern
NH to upper 50s near the international border with dewpoints ranging
from the upper 50s to upper 40s. As the surface low tracks through
the St Lawrence Valley it will drag a cold front through the area
Friday evening and night. SPC has a marginal risk to our west for
severe thunderstorms, but an analysis of model soundings show that
there will be a cap over our area so confidence is not high enough
to put thunder in the forecast at this time.
There will be a chance of rain showers with the warm front
Friday morning followed by a possible lull as we enter the warm
sector followed by scattered rain showers Friday afternoon into
Friday night as the cold front crosses the area. Colder air
will work into the area late Friday night into Saturday morning
changing any mountain rain showers to snow showers.
Cool high pressure will build in from Canada Saturday for cooler and
drier weather through early next week. Towards the middle of next
week flow at 500 mb will become more zonal with a couple fast moving
waves passing near southern New England bringing increasing chances
of precipitation by Tuesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Short Term...VFR prevails through tonight with increasing
clouds from the west. A crossing wave will initially bring IFR
in SN across southern terminals, then MVFR as snow switches to
RA for all terminals by mid-day. Conditions may briefly improve
during the afternoon as precipitation moves east, especially
over the Connecticut Valley. Then, onshore flow increases again
with possible restrictions along the coast in BR and lowered
ceilings.
Long Term...Areas of MVFR/IFR Friday in SHRA and lowering CIGS.
Conditions improve this weekend as high pressure builds in from
the NW.
&&
.MARINE...
Short Term...Smooth sailing amid onshore flow continues through
tonight. A wave crosses Thursday with rain showers, then
remnant low pressure wanders northeastward off the New England
coast into Thursday night with a rise in seas and gusts. SCAs
are expected during this period at least over the outer waters
with a chance of SCA seas/brief SCA gusts in the bays.
Long Term...Seas 5-7 ft along with increasing SW flow ahead of
cold front Friday. Winds will gust 25 to 30 kt starting around
15Z Friday morning. Winds and seas remain elevated behind the
front into Saturday morning followed by quiet conditions into
early next week under high pressure.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 11 AM Thursday to 2 AM EDT Friday
for ANZ150-152-154.
&&
$$
JC
Area Forecast Discussion
National Weather Service Wichita KS
1003 PM CDT Wed Mar 18 2020
...Evening Mesoscale Update...
.MESOSCALE DISCUSSION...
Issued at 958 PM CDT Wed Mar 18 2020
01z/8pm SFC analysis shows a warm/semi-stationary front draped
generally west to east across southern Kansas, with a less-defined
dryline running north-south from SW KS into the TX Panhandle.
Additionally, there appears to be a less- defined west- east
boundary near the Red River Valley. Convergence along that
southern boundary combined with a lead, upper level wave appears
to be responsible for the ongoing convection from southwest into
central Oklahoma. Latest RAP analysis shows the nose of increasing
elevated moisture transport is infringing on this convection at
this time. North of that convection, SPC mesoanalysis shows a
pocket of more stable air from northwest OK into southern KS.
Oftentimes, increasing elevated moisture transport will aid in
evening/nighttime destabilization, but the caveat tonight is the
ongoing convection over OK, and whether or not this will disrupt
the northward return of the better quality/deeper moisture
overnight. Based on recent radar trends, it does appear that this
disruption is occurring. As the LLJ strengthens and moisture
transport increases, there still may be enough moistening to allow
some deeper convection to develop.
Based on all that, here are a few possible scenarios. There appears
to be a small MCV developing with the convection over OK and, based
on the mean flow, may move across SE KS overnight, probably with a
gusty wind and heavy rain threat.
To the west of that feature, the dryline will become better
defined as low-level moisture "sloshes" back into western OK.
Increasing large- scale forcing for ascent combined with
increasing convergence along the dryline and the warm front may
allow convection to develop over the TX Panhandle and build
northeast into Kansas, or potentially even develop over Kansas.
Confidence on development away from the ongoing OK convection is
lower, though, which also makes confidence in severe weather
lower. If enough moistening can occur, there still may be enough
instability for a few strong to marginally severe storms capable
of dime to quarter size hail and perhaps some gusty winds.
Overall, the severe threat appears to be lower for now. We`ll
continue to monitor trends and update as needed.
Martin
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 322 PM CDT Wed Mar 18 2020
Pesky low clouds continue to impact portions of the forecast area
this afternoon, as weak isentropic upglide continues just off the
surface. Seeing some signs of the clouds breaking up across south
central KS, as warm advection continues to push north into the area.
With max temps making a "late inning rally".
For the evening hours, expect strong 850-700h moisture transport to
gradually increase across south central KS and eventually across the
entire area for the evening hours. This is in response to a
shortwave ejecting northeast out of the SW Conus. Expect widespread
showers and storms to develop initially over western OK, ahead of a
dryline, with this convection making its way northeast into the
forecast area late this evening, towards midnight. This is a tad
slower than previously thought, but looks like widespread showers
and embedded thunderstorms will move across most of the area after
midnight. Latest GFS and NAM/WRF both suggest a high shear and low
CAPE setup, with bulk shear of 50-55 kts and mlcape values 500-100
j/kg. So think some strong storms may race NE across the forecast
area overnight. Cannot completely rule out a token severe storm,
given this environment, with quarter size hail and 60 mph winds the
main threats. Most of the higher precipitable water (PW) values look
to stay further to the SE of the forecast area, but with that said
PW values will still be 100-150 percent of normal across SE KS. So
still could see some localized flooding for areas east of the KS
Turnpike. The limiting factor for flooding will be the rapid
movement of the system, limiting QPF amounts as it moves NE by Thu
morning. Some areas in SE KS may pick up another half an inch of
rainfall by Thu morning.
By Thu morning, most of the convection will sweep to the northeast
of the forecast area, as a prominent mid level dry slot sweeps
north, with a developing low pressure system expected for move
across western KS into central KS. As this low deepens, expect a
strong pressure gradient to develop to the east of the low, with
very strong winds expected across most of the forecast area for the
daytime hours on Thu. Could see sustained winds of 30-35 mph with
gusts to 45 or 50 mph. So have hoisted a wind advisory for the
entire area for the daytime on Thu. With the strong winds, comes
increasing concerns about fire weather, especially for areas across
central KS, where rainfall hasn`t been as heavy. See the fire
section below.
Much colder air will push south across the forecast area for Thu
evening. This could lead to chances for some post frontal light
precipitation across central KS for Thu evening. The main concern
for Thu evening into early Fri, will be much colder temperatures
with minimum temperatures falling below freezing by Fri morning with
the below normal temps expected for Sat morning as well.
Ketcham
.LONG TERM...(Sunday through Wednesday)
Issued at 322 PM CDT Wed Mar 18 2020
Medium range models differ on how they want to handle a weak impulse
expected to move across the plains late Sat night through early Sun
morning. Moisture looks a little overdone, with GFS showing this
drier trend, while the ECMWF showing a chance of mix of light
rain/snow for Sunday morning. Will keep some low pops in for now,
but could see these removed with later forecasts.
Upper pattern looks to remain active for the start the work week as
the area remains in west/sw flow aloft with a series of upper
disturbances moving through. GFS is even showing a chance for
storms again on Mon evening.
Ketcham
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 641 PM CDT Wed Mar 18 2020
*TSRA to impact the region tonight*
TSRA have quickly developed this evening from west Texas east
along the Red River Valley. There are a few possible scenarios
with this activity. 1) The storms remain organized and continue to
move north/northeast, eventually moving across parts of central
and easter Kansas later this evening and tonight. 2) The storms
near the Red River weaken, with new development over Kansas
overnight. 3) The storms over the Red River congeal into a larger
complex that tracks northeast and clips parts of SE Kansas,
possibly leaving central Kansas with a lower chance of SHRA/TSRA.
For now, thinking the best chance of TSRA will be southern Kansas
and that is where I have left a mention in the TAFs. We`ll
closely monitor trends through the night and update as needed.
Otherwise, MVFR CIGs should redevelop across the area overnight as
low-level moisture increases. Where TSRA do occur, gusty winds
(to 50kt) and hail will be possible, along with reduced VIS
(2-5SM). LLWS will be a concern overnight as well as a 35-45kt LLJ
overspreads the area. On Thursday, a dryline will punch through
the area, clearing out the low clouds and increasing the SFC
winds. Those winds will likely gust as high as 35-40kt in the
morning, increasing even further Thursday afternoon.
Martin
&&
.FIRE WEATHER...
Issued at 322 PM CDT Wed Mar 18 2020
Very high to extreme grassland fire danger is expected on
Thursday. Strong gusty winds are expected across the area on
Thursday. Expect southwest sustained winds of 30 to 35 mph with some
gusts as high 50 mph on Thursday afternoon. Relative humidity values
are expected to fall into the 25 to 35 percent range, with the
lowest values expected across central Kansas. Current thinking
suggests recent rainfall (and expected rainfall tonight) has led to
a quick greenup for areas east of Interstate 135. There is some
concern about extreme grassland fire danger over central Kansas, for
areas that haven`t gotten as much rainfall. So a fire weather watch
has been posted for this chance, for areas northwest of a
Kingman to Salina line.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 60 76 28 41 / 70 10 0 0
Hutchinson 57 73 25 39 / 60 10 0 0
Newton 58 75 26 39 / 70 30 0 0
ElDorado 60 76 28 41 / 70 30 0 0
Winfield-KWLD 63 77 30 44 / 80 30 0 0
Russell 52 69 21 38 / 60 10 20 0
Great Bend 54 69 22 39 / 50 10 10 0
Salina 54 72 24 38 / 60 20 10 0
McPherson 56 73 24 38 / 70 20 10 0
Coffeyville 64 78 34 44 / 90 60 0 0
Chanute 61 77 32 41 / 90 60 0 0
Iola 60 77 31 41 / 100 60 0 0
Parsons-KPPF 63 77 34 43 / 90 60 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM to 7 PM CDT Thursday for KSZ032-033-
047>053-067>072-082-083-091>096-098>100.
Fire Weather Watch from Thursday morning through Thursday
evening for KSZ032-033-047>051-067-082.
&&
$$
MESOSCALE...RM
SHORT TERM...Ketcham
LONG TERM...Ketcham
AVIATION...RM
FIRE WEATHER...Ketcham
Area Forecast Discussion
National Weather Service Marquette MI
639 PM EDT Wed Mar 18 2020
.SHORT TERM...(This evening through Thursday Night)
Issued at 413 PM EDT WED MAR 18 2020
Water vapor imagery and RAP analysis show split flow pattern over
western N America. In the southern stream, a mid-upper level trough
is situated over the West Coast with low amplitude ridging
downstream into the Central Rockies and Central Plains. In the
northern stream, a mid-upper level trough dominates much of Canada.
Within the base of the southern stream trough, a very well-defined
shortwave off the Baja CA coast will be the feature of interest for
the forecast here later Thu into early Fri as it races ne ahead of a
northern stream shortwave dropping se toward the Upper Lakes.
Initial weaker shortwave in the southern stream moving through the
Central Plains supported convection from southern WI/Lower Mi to ne
TX this morning. This shortwave will continue to move through the
Ohio Valley tonight tracking along and north of its associated warm
frontal boundary supporting convection along the way. A few very
spotty showers occurred over the U.P. today, but otherwise dry
conditions have been the rule under weak high pressure and a dry
low-level air mass.
Later tonight, there is some increase in isentropic ascent, mainly
over the w half of Upper MI. Moisture transport also begins to lift
toward that area. Will thus have a gradual increase in pops across
the western third of the fcst area, particularly late. With sfc
temps likely slipping just blo freezing for most locations and fcst
soundings showing the potential of either a warm nose aloft above
freezing or possibly moisture not extending high enough to reach at
least -10C for ice nucleation, ptype may end up mostly as -fzdz.
Some -sn is also possible, mainly across nw Upper MI. Icy spots
could be a concern late tonight if pcpn does develop.
During the day Thursday, a closed low over the desert southwest will
eject a shortwave into the Central Plains as a positively tilted
trough sinks south through central Canada. The shortwave over the
Plains will lift northeast through the Upper Great Lakes overnight
Thursday night ahead of the trough swinging through Canada. Precip
should generally move west to east during the day Thursday with the
better chances in the west beginning mid-morning, becoming likely
across the UP by mid to late afternoon and evening. Surging of warm
air at 850-700mb and freezing temps at the sfc could still lead to
some freezing dz/-ra for a couple of hours in the morning before the
change over to rain. Expect high temps on Thu generally in the upper
30s to lower 40s.
As the shortwave and associated sfc low lift into WI and then toward
the Mackinac Straits Thursday night, winds will shift to the north
and CAA will drop temps through the column, transitioning precip to
snow across the region. Coupled upper jet structure with one jet max
over northern Ontario and northern Quebec and another nosing into
the mid-Mississippi Valley/Midwest will lead to strengthening fgen
especially toward the evening hours across the U.P. This strong
forcing along with perhaps a surge in the IVT (integrated water
vapor transport) as hinted at by the NAM could lead to enhanced pcpn
totals in the late afternoon/evening hours. Ended up going with WPC
guidance which reflected higher totals of an inch or more over the
west and north central portions of the cwa. Some of this higher qpf
is likely due to lake and terrain enhancement as winds shift
northerly. Highest snowfall totals continue to be over the west and
north central higher terrain where 4 to 7 inches is possible at some
locations, particularly from Ironwood north through the spine of the
Keweenaw and over the Huron Mtns. It`s very possible that headlines
will be needed for the west and Keweenaw and perhaps Baraga and
Marquette counties as well for the combination of moderate snow
accumulation and strengthening north wind gusts of 30-40 mph leading
to areas of blowing snow, lowered visibility and hazardous travel
late Thu night into Fri morning. Given that this is a late 3rd to
4th period event will hold off on specific headlines for now, but
instead issue a SPS to highlight potential hazards. Will also
include a mention of possible beach erosion and localized lakeshore
flooding in SPS along the Lake Superior shore from the tip of the
Keweenaw to areas east of Marquette.
.LONG TERM...(Friday through Wednesday) Issued at 507 PM EDT WED
MAR 18 2020
On the large scale, persistent ridging and positive height anomalies
over the N Pacific will continue to drive downstream troughing
across the western CONUS. This strong ridging will facilitate some
blocking upstream as the beginning of the longterm period will see
an active storm track across the central CONUS as high pressure
moves into the Northern Plains on Friday, keeping most of the
activity south into the Ohio River Valley and Appalachians. Behind
this high pressure, a quasi-zonal flow pattern will emerge across
the central CONUS before deterministic and ensemble models suggest
the return of a more active storm track across the central CONUS
towards the end of next week.
As the system mentioned in the short term AFD pulls out on Friday,
moderate pressure rises and CAA on the backside will maintain some
LES in the NW wind snow belts with gusty conditions and blowing snow
looking likely...especially along the Lake Superior shoreline. High
pressure will slowly build in from the west through the day as drier
air accompanies it. This will look to cut off any remaining LES from
west to east. GFS/GEM/EC begin to cut off LES across the west in the
early afternoon, with the NAM holding on to LES through the entire
day. Model soundings support LES SLR`s in the 18-20:1 range with
most of the profile in the DGZ and saturated.
With high pressure in control by Friday evening LES snow will
finish, but expect some lake-effect clouds to remain with colder air
aloft and winds off the lake. High temperatures will then moderate
through the rest of the weekend into next week becoming 5 to 10
degrees above normal by mid week. Otherwise, nothing too noteworthy
within the forecast period, but a wave passing through the central
CONUS Tuesday/Wednesday may bring some precipitation into the UP.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 638 PM EDT WED MAR 18 2020
MVFR conditions will redevelop at all sites this evening as moisture
increases ahead of a storm system emerging from the central Plains.
IFR/LIFR conditions are expected by Thursday morning at all sites as
increasing moisture leads to the onset of mainly rain showers.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 413 PM EDT WED MAR 18 2020
A fairly strong low pressure system is still expected to track from
southwest to northeast across the lake Thursday night. Current
forecast has N gales across the lake late Thu night into Friday
morning in the west and in the east a through Friday and a gale
watch has been issued. High end gales with some storm force gusts
will be possible over the central portion of the lake Friday
morning. High pressure building in late Friday into the early
portion of next week across the Upper Great Lakes will diminish
winds to generally 20 knots or less.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Heavy Freezing Spray Warning from 6 AM to 8 PM EDT Friday for
LSZ243>245-248>251-263>267.
Gale Warning from 7 AM to 8 PM EDT Friday for LSZ251-267.
Gale Warning from 2 AM to 8 PM EDT Friday for LSZ245>250-265-266.
Gale Warning from midnight EDT /11 PM CDT/ Thursday night to 11
AM EDT /10 AM CDT/ Friday for LSZ162.
Gale Warning from midnight Thursday night to 8 PM EDT Friday for
LSZ243-244-264.
Gale Warning from midnight EDT /11 PM CDT/ Thursday night to 4
PM EDT /3 PM CDT/ Friday for LSZ240>242-263.
Lake Michigan...
Gale Watch from Friday morning through Friday evening for LMZ221-
248-250.
&&
$$
SHORT TERM...Voss
LONG TERM...JAW
AVIATION...07
MARINE...Voss
Area Forecast Discussion
National Weather Service Norman OK
558 PM CDT Wed Mar 18 2020
...New AVIATION...
.SHORT TERM...
(This evening through Thursday)
Issued at 235 PM CDT Wed Mar 18 2020
Several weather concerns are present in the short term, including
severe thunderstorms, flooding, and gradient winds.
Current observations show gradually diminishing stratocumulus
band oriented from the Lawton area northeastward along and south
of I-44, roughly. This is coincident with more significant low-
level moisture and has suppressed surface heating and limited
temperature increase somewhat this afternoon. HCR evolution has
been evident over the last hour or so within diminishing
stratocumulus band, but deeper cumulus is occurring across north
Texas near and south of residual synoptic boundary/evolving warm
front where deeper moisture resides. In fact, some glaciation has
been observed in visible satellite indicating isolated convective
initiation is probably occurring. Coverage of thunderstorms is a
little uncertain through the afternoon since more significant
midlevel height falls and large scale ascent is still at least a
few hours away. Nevertheless, RAP forecast soundings show fairly
deep/moist boundary layer advecting northward and modest residual
capping EML will become less effective at suppressing convection
toward evening. A period of discrete supercells is possible late
afternoon through mid-evening, at which time upscale growth should
accelerate and an eventual mature/intense MCS should evolve.
Exact placement and timing will be dictated by mesoscale details
that are still evolving and should become more clear in the next
few hours.
With the initial development, if it matures late this afternoon,
large hail would be the primary threat. As low level flow
increases considerably toward evening, low-level shear values
become concerning and the tornado threat will increase. It`s
important to note that the tornado threat likely won`t diminish
overnight despite evolution of storm mode. QLCS tornadoes will
still be possible given the magnitude of low-level shear and
near-ground instability. We won`t decouple sufficiently to
preclude the tornado threat. QLCS tornado threat will be highest
along bowing segments that are more oriented northwest to
southeast (i.e., from the apex of the bow northward) where deep
layer shear vectors are oriented more normal to the line. These
will be the sections of the line to watch closely late evening
through the night, in addition to the larger scale convective wind
threat. The threat of large hail will decrease as the linear
evolution continues.
The other concern is flooding. We have issued an initial Flood
Watch from this evening through tomorrow morning for portions of
south-central and southeast Oklahoma, where antecedent conditions
are lease tolerant of high rainfall rates. Several rounds of rain
have occurred and this has led to saturated ground. Even a brief
period of heavy rain could cause flooding across this area. It`s
important to note that even further north, rates could exceed
flash flood guidance, and at least in urban areas like Oklahoma
City that see heavy rates some flooding/flash flooding is
possible. Current expectation of heavier rain being progressive in
nature should preclude a more widespread/significant flooding
event.
Strong winds are possible tomorrow as deep mixing and momentum
transfer begin late morning and persist until early evening. A
Wind Advisory has been issued where wind gusts could approach 50
mph across roughly the northeast half of the area including all of
northwest Oklahoma. Winds nearly as strong could occur behind the
front that is expected to move through during the evening.
Some initial attack fires could occur given the wind and RH, but
recent rains and wet fuels (<25 percentile ERC values) should
preclude significant spread, however.
BRB
&&
.LONG TERM...
(Thursday night through next Tuesday)
Issued at 229 PM CDT Wed Mar 18 2020
By Thursday evening, the nearly vertically stacked upper and surface
low across Kansas will be lifting toward the U.S. Great Lakes
region, as its adjacent cold front boundary will begin its push
across the Southern Plains. With the surface high way up in
Saskatchewan, the cold Canadian based air will not be lagging too
far behind the surface boundary as it filters into Oklahoma. The
GFS, NAM, and ECMWF all in agreeance pushing the boundary layer
critical thickness (1300 m) well into northern Oklahoma, so
confident about unseasonably winterlike low temperatures for
Thursday night/Friday morning. Temperature across northern and
western Oklahoma should fall at to just below freezing, with lows
across central and southwest Oklahoma in the mid to upper 30s.
Western north Texas and southeast Oklahoma should see lows around
40 degrees. In addition, the north winds will produce wind chill
values in the teens across northwest Oklahoma, to the 20s across
central and southwest Oklahoma.
Unseasonably cooler temperatures will persist through the weekend.
However, both GFS & ECMWF are consistent with our southwest flow
aloft bringing in a low amplitude shortwave trough Saturday night.
Both aforementioned models suggests a plume of moisture vector
transport in the mid-levels (850-700 mb layers) from south to
north across Texas, however the European model is less aggressive
and cuts it off near the Red River. Convective indices and model
soundings at this point showing only weak elevated instability and
moist adiabatic to nearly 700 mb, so most likely will be just
light rain with only a slight chance at this point for a
thunderstorm. POPs for light rain with a mention of thunder will
remain in the grids from Saturday evening and overnight, and
should be east of I-35 by sunrise Sunday morning.
By Monday, another surface low will be developing across eastern
Colorado, bringing a return of windy and warmer southerly air. This
will kick off the start of a warming trend through mid-week, with
seasonably average temperatures for Monday, and warmer than
seasonably with mild temperatures well in the 70s. A weak upper
level wave will off the Rockies will be steering the lee low
eastward, pushing in a weak cold front into the Southern Plains on
Tuesday. Both GFS & ECMWF suggests some war air advection ahead of
the surface boundary could produce some showers and thunderstorms
Monday night, but differ on the location of the QPF. For now, will
introduce low POPs for Monday night east of I-35, which is in more
agreeance with the ECMWF solution.
&&
.AVIATION...
(00Z TAFS)
Issued at 540 PM CDT Wed Mar 18 2020
Showers and strong thunderstorms are beginning to develop, which
should be affecting all of our terminals between this issuance and
03Z when conditions may degrade from current VFR to MVFR as
ceilings lower and storms become more organized. Although the
storms could become severe after this issuance, expecting the
heaviest rain associated with the storms sometime between 07-11Z.
Conditions could degrade to IFR for a time under these storms as
ceilings further lower along with visibilities. Around 15Z,
expecting the storm acidity to decrease, with VFR conditions at
all terminals through the remainder of the forecast. Expect breezy
surface winds to shift southwesterly by 19Z with windspeeds
increasing to 20kts while vertical mixing could produce wind gusts
at 30 to 35kts through the rest of this forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 61 74 35 46 / 100 50 0 0
Hobart OK 58 72 34 48 / 70 20 0 0
Wichita Falls TX 62 75 41 51 / 100 20 0 10
Gage OK 53 69 27 46 / 70 0 0 0
Ponca City OK 61 75 31 46 / 100 30 0 0
Durant OK 64 77 45 54 / 90 80 10 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Wind Advisory from 10 AM to 7 PM CDT Thursday for OKZ004>012-
014>018-021.
Flood Watch through Thursday afternoon for OKZ043-047-048-051-
052.
TX...None.
&&
$$
SHORT TERM...12
LONG TERM....08
AVIATION...68
Area Forecast Discussion
National Weather Service Springfield MO
619 PM CDT Wed Mar 18 2020
.SHORT TERM...(This evening through Thursday)
Issued at 243 PM CDT Wed Mar 18 2020
A warm front will continue to lift north though the area this
evening. CAMs are pretty quiet on the convective front this
evening, however the RAP does indicate that capping may be
relatively weak for parcels lifted from the low-levels of the
atmosphere. Will therefore carry 20-30% PoPs to cover any isolated
to widely scattered activity that can get going within the
diffluent flow aloft. We may actually see some fog development
over parts of south-central Missouri later this evening if
coverage of convection remains limited.
Much better chances for showers and thunderstorms will start
later tonight as upper level energy begins to emerge across the
southern high Plains. Short term models are consistent in
depicting a low-level jet strengthening and nosing into
southwestern Missouri beneath the aforementioned diffluent flow.
CAMs are consistent in bringing convection northeast out of
Oklahoma and northern Arkansas starting after 06Z.
We have posted a Flash Flood Watch for most of the Missouri Ozarks
and parts of southeastern Kansas given the saturated ground
conditions and the potential for 1-3" of rainfall starting late
tonight.
There may still be a low-end risk for localized wind damage with
storms along and west of the I-49 corridor late tonight. However,
most storms from tonight into Thursday morning are expected to be
non-severe.
The potential for severe storms will then increase Thursday
afternoon as that low pressure system tracks northeast across the
central Plains. The main key to severe weather potential across
the Missouri Ozarks will be how much the atmosphere destabilizes
behind the morning convection. There appear to be two possible
scenarios:
1) Convection remains fairly widespread into the afternoon due to
the synoptic scale lift ahead of that main low. If that occurs,
the severe threat may be held down some.
2) The more widespread convection diminishes by late morning with
the atmosphere recovering in the afternoon. This would support a
greater risk for severe storms in the afternoon and evening. This
would include the risk for a few tornadoes.
We will get a better handle on the mesoscale environment later
tonight and especially Thursday morning once the first round of
storms plays out.
Meanwhile, the risk for flash flooding will persist into
Thursday. Again, the amount of convective coverage will be key
regarding flood potential. This would include the potential for
training.
One other note for Thursday will be strong and gusty southwest
winds developing near and west of the I-49 corridor late in the
afternoon with the passage of a surface trough. Those areas may
approach Wind Advisory criteria.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 243 PM CDT Wed Mar 18 2020
The threat for severe storms will persist into Thursday evening
across south-central Missouri. A cold front will then sweep
through the area later Thursday night. Much colder temperatures
are then expected into the weekend. Lows in the 20s look like a
good bet for Friday night.
Models then continue to advertise short wave energy bringing more
light precipitation into the region from later Saturday night into
Sunday. There is still some potential for light wintry
precipitation, although no road impacts are expected.
Global models and ensembles then remain consistent bringing more
short wave energy through the area from next Monday night into
Tuesday. This would be our next shot at showers and perhaps some
thunderstorms. Much warmer temperatures are expected by this
period with highs returning to the upper 60s and lower 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 619 PM CDT Wed Mar 18 2020
VFR conditions can be expected at the TAF sites through the
evening hours ahead of the next approaching system. As showers and
thunderstorms push into the region during the early morning hours
Thursday (07Z to 09Z) conditions will become MVFR. A few
instances of IFR conditions will be possible within heavier
thunderstorms. Expect this activity to stick around through the
middle morning hours before departing to our east. Meanwhile,
surface winds will be primarily out of the south through tonight
and tomorrow. Winds will gust at all TAF sites at 25 to 30 knots
as this system strengthens across the Plains. Additionally, there
will LLWS of 40 to 45 knots late tonight into tomorrow morning. A
second round of activity is expected Thursday afternoon into
Thursday evening, with KBBG and KSGF being the primary impacted
TAF sites.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Flash Flood Watch from 1 AM CDT Thursday through Thursday
evening for MOZ068>071-077>083-088>098-101>105.
KS...Flash Flood Watch from 1 AM CDT Thursday through Thursday
evening for KSZ097-101.
&&
$$
SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Perez
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Thursday)
Issued at 345 PM CDT Wed Mar 18 2020
A brief glimpse of summer weather will be afforded to the region
tonight and tomorrow, including the threat for strong to severe
storms.
A highly amplified eastern Pacific upper level omega blocking
pattern has led to the formation of a deep, quasi-stationary H300
trough along the North American West Coast. GOES-E water vapor
imagery this afternoon shows a compact, but potent energy lobe
preparing to eject northeastward from the base of this trough over
the northern Baja regions of Mexico. This negatively-tilted wave
lifts northeastward through the overnight period and through
Thursday, with the wave axis positioned over the forecast area by
Thursday evening. A leading low-amplitude shortwave this morning
has long since cleared the area with a small region of trailing
subsidence producing transient breaks in the cloud cover before
convective temperatures were reached and a stratocumulus field
developed.
A broad warm front consisting of at least two foci of enhanced
convergence was situated over the region this afternoon--with
visible satellite imagery showcasing a very distinct cloud
gradient denoting the leading edge of the southern baroclinic
zone. Increasing theta-e advection to the south of this zone is
leading to the development of light showers/drizzle on radar
imagery along a NW to SE line from Ottawa to Anderson counties.
The warm front has moved little early this afternoon owing to a
lack of upper level height falls. Once the aforementioned
shortwave ridge passes through later this afternoon, the warm
front and attendant precipitation should begin to lift northward.
Attention then turns to the evolution of the pattern tonight.
Increasing WAA should buck any significant diurnal drop in
temperatures this evening, with some locations possibly seeing
rising temperatures after midnight. Dewpoints likewise climb close
to 60 degrees overnight. Showers and thunderstorms are expected
to form in response to increasing theta-e advection in conjunction
with a strengthening H850 LLJ under a convectively unstable
profile. The exact timing of the convection is still a bit
uncertain based on output from the 12Z HREF, but the best window
for storms looks to be in the 09Z to 14Z timeframe. RAP forecast
soundings do denote a region of higher static stability right
above the surface, but elevated parcel origins may be less than 1
kft AGL. Modest mid-level lapse rates will lead to 1200-1700 J/kg
of MUCAPE available for realization by any storms that do develop
tonight. The deep shear profiles are not quite as impressive as
they were in yesterday`s model runs, but may still support
organized storm structures.
Storm mode may be more complex/multi-cellular in nature given the
multiple inflection points in the forecast hodographs, though
modest low-level helicity values for any deviant right-moving
storm motions does still raise a non-zero tornado concern IF--and
this is a strong if--the storms can modulate the environment to
ingest surface-based parcels. Early morning is a climatological
unfavorable time for tornadoes given the typical high static
stability of the BL, but the lower than average effective inflow
region bears watching. DCAPE values are a modest 700-900 J/kg, and
with the presence of a 40 kt LLJ that could be tapped by
downdrafts, it would not take much additional momentum to create
severe level surface wind gusts. Hail is also a concern for any
sustained updrafts, but with the complex storm mode anticipated
and broad region of lift supporting clusters of updrafts, the
sustainability of these cells is somewhat in question. The removal
of most of the SPC Day 1 Hail Outlook from the forecast area
supports this assessment of the pre-storm environment.
This complex of convection lifts northeastward and out of the
area by mid-morning Thursday as a lee cyclone matures and begins
to pull east of the Front Range. A Pacific Front races eastward
ahead of this low, passing through the forecast area by 21Z. While
the triple point and best tornado potential should be just north
of the forecast area, additional convection my develop just ahead
of this feature in the early afternoon hours. All hazards will be
possible with this convection, with right or left moving
supercellular structures possible given the unidirectional shear
profiles. With H700 flow at 70 kts, storm motions of 40 to 50 kts
are not out of the question. The best threat for convective
development will be along and southeast of the Turnpike early in
the afternoon, with storms racing northeast and into Missouri by
mid-afternoon. Should the front slow--as it has from yesterday`s
model runs--the threat for severe weather may last longer into the
afternoon and be more widespread.
The attendant dry-slot works into the forecast area during the
afternoon, with ample boundary layer mixing to tap into a 40 to 50
kt jet at H850-700. Did issue a wind advisory for portions of the
southern forecast area during the afternoon where confidence of
wind gusts of 45 mph or more is the highest. Dewpoints should
rapidly fall owing to this subsidence and mixing, though how much
is of some question. Did trend the forecast towards the 25th
percentile of the dewpoint guidance, dropping afternoon RH values
to around 30 to 35 percent in the Flint Hills and locations to the
west. Fine fuels such as grasses should have time to dry
sufficiently to support fires, thus a very high fire danger is
expected during the strongest winds in the afternoon.
.LONG TERM...(Thursday night through Wednesday)
Issued at 345 PM CDT Wed Mar 18 2020
Temperatures nose-dive behind a cold front Thursday night and remain
cold into the weekend, with a slow moderating trend through early next
week.
As the overall extratropical system lifts northeastward, winds
should decrease ahead of a sharp cold front that enters north-
central Kansas late in the afternoon or during the early evening
hours on Thursday. This front races southeastward and should clear
the forecast area shortly after midnight. A tight pressure
gradient and differential CAA will support winds of 20 to 30 mph
with gusts over 40 mph overnight, decreasing during the day on
Friday as colder air settles into the region. Highs on Friday
will struggle to reach the mid-30s to around 40 degrees. Lows
Friday night may plummet into the teens to low 20s with the
passage of the surface ridge axis. A moderating pattern settles
into for the weekend and the first half of next week with return
southerly flow and a chance of rain Sunday evening. Model
solutions diverge significantly in the evolution of the pattern
beyond this weekend when the pattern de-amplifies. The next
significant chance of showers and storms may come on Tuesday, but
confidence in the details of this system remain on the lower side.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 633 PM CDT Wed Mar 18 2020
Early in this period, CIGS may be high-end MVFR/low-end VFR for a
few hours before decreasing to IFR around 03Z. Thunderstorms are
expected to develop south of terminals and move in overnight. Rain
and storms should quickly advance to the north and end at airports
by 14Z, which is also when VFR conditions should return. South-
southwest winds become strong after sunrise Thursday, gusting as
high as 35 to 40 knots tomorrow afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 1 PM to 6 PM CDT Thursday for KSZ034>038-054-
055-058-059.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Teefey