Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/23/20
Area Forecast Discussion
National Weather Service Caribou ME
915 PM EST Wed Jan 22 2020
Weak high pressure to build across the region tonight followed
by a cold front on Thursday. The cold front will push south
across the area Thursday night into early Friday morning. Low
pressure will approach area from the south on Saturday and
track along the Downeast coast Sunday. The low is expected to
move east of the region by Monday.
.NEAR TERM /THROUGH THURSDAY/...
9:15 PM Update...Adjusted temps again mostly to bring them down,
especially in valley areas. Also increased cloud cover through
mid evening. Otherwise, no major changes this hour.
WAA continues through the night w/lower clouds holding on longer
given the light south winds and warming aloft. Temps have
warmed nicely into the 20s north and upper 20s and lower 30s
central and downeast areas. UA showed the upper flat ridge
building over the region. This ridge is expected to pass to the
east tonight. Leaned close to the NAM12 and NBM for sky setup
keeping more clouds over the region into late evening,
especially across the northern and western areas. Further s,
clearing will be there through much of the evening allowing for
temps to drop off quicKLY. The clouds across the northern areas
will keep temps up. Model soundings do show WSW flow to take
hold later at night allowing for some mixing to lead to some
partial clearing. This clearing however will be short lived as
more clouds move in ahead of a weak cold front by early Thursday
For Thursday, the WSW flow continues w/the weak cold front
slated to slide across the region during the day. There is some
weak forcing noted by the NAM and GEM as well as the RAP to
support some scattered snow showers/flurries mainly across the
far n and w during the morning hrs. Some warming ahead of the
front shown by the model guidance and supported by today`s UA to
support daytime temps pushing well into the 30s across the
north w/near 40F for southern areas. Used a blend of the
guidance(GEM/NAM) to w/low- mid 30s northern 1/2 of the CWA
w/upper 30s to lower 30s central and downeast areas.
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A dry cold front stretching from a low north of Labrador will
cross Thursday night into early Friday morning. Clouds will
limit lows to the upper teens to lower 20s. There`s not a lot
of cold air advection behind the front and highs on Friday will
only be around 5F colder than Thursday. High pressure behind the
cold front in Quebec will sink southward towards the Gaspe
Peninsula and New Brunswick. As this happens, a moist low level
east flow will develop with a lot of low clouds developing as
early as Friday afternoon...and certainly Friday night into
Saturday. There may be enough clearing on Friday night in
Aroostook County to generate lows in the single digits and
teens, but in the 20s elsewhere under cloud cover. The cloud
cover will continue for the entire area on Saturday as cold air
damming sets up ahead of the approaching low from southern New
England. This means Saturday`s highs will be several degrees
cooler than Friday. In general, expect precip to hold off the
entire area during Saturday as an upper ridge builds.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The long term forecast is dominated by a vertically stacked low
pressure system that will slowly meander eastward from the Ohio
River Valley...or eastern Great Lakes region Saturday evening
towards the Midcoast by Sunday evening. A triple point low is
expected to form along the occlusion near New York City Saturday
evening as a shortwave rotates around the upper low. In
general, the trend with today`s 12Z guidance has pushed the
occlusion further north through the forecast area on Sunday. As
a result, have bumped up PoPs through the event. There`s not a
lot of cold air aloft in place with the onset of the event, but
there is cold air damming which makes mixed precip possible. The
22/12Z GFS remains the coldest guidance while this morning`s
ECMWF and GEMS are considerably warmer. Blended GFS and ECMWF
thermal profiles to yield the mixed precip towards Bangor and
the Downeast region Saturday night into Sunday morning with rain
on the coast and all snow towards Aroostook County. The precip
is forecast to transition towards snow Sunday afternoon and
evening. Overall confidence in P-types is not high. The
occlusion is currently expected to slowly weaken as it
propagates northward towards Aroostook County later Sunday, but
that could change as we get a better handle on shortwaves
rotating around the closed low Saturday night into Sunday night.
The speed of the cut-off low out of the area is also uncertain
and have maintained PoPs into Monday. The remainder of the
period looks dry with above normal temperatures.
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: MVFR cigs across northern terminals, mainly n of
KHUL through about 05z and then cigs look like they will lift to
VFR into Thu. There is a risk of TEMPO IFR this evening mainly n
of KCAR. VFR expected for KBGR/KBHB into Thursday. Another item
to consider into late tonight will be some LLWS mainly for the
northern terminals given the 35-40 kt WSW flow around 2-3k ft.
Thursday night into Friday morning...MVFR tempo IFR cigs north
of HUL...otherwise VFR.
Friday afternoon and evening...VFR
Friday night into Saturday night...Becoming IFR towards BGR and
BHB. Tempo MVFR cigs further north.
Saturday night into Monday morning...IFR vis at times in snow.
Chance of freezing rain later Saturday night into Sunday morning
NEAR TERM: No headlines expected this term. SW winds are
forecast to increase to sustained 10-15 kt w/gusts hitting 20-25
kt tonight into early Thursday. This will mainly be across the
outer zones. Seas 2-3 ft into Thursday.
SHORT TERM: Continue to expect a gale Saturday night into
Sunday. An SCA may be required later Monday afternoon into
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
812 PM CST Wed Jan 22 2020
Fog development is ahead of schedule per METARs and public
reports from near Goliad south to Robstown and Kingsville, so
have updated accordingly to show areas of fog expanding SW
through much of the CWA overnight. Dense fog is likely at times,
but its coverage in the next few hours may stay localized enough
to forego a Dense Fog Advisory. Thereafter, the HRRR and RAP are
very bullish in carrying dense fog west into the Rio Grande Plains
by daybreak which seems plausible. Besides removing thunder
mention this evening for the back edge of showers, no other
updates are planned at this time.
.PREV DISCUSSION... /Issued 541 PM CST Wed Jan 22 2020/
00Z aviation discussion follows.
Leading edge of VFR ceilings was just west of CRP at 530 PM and
should make some gains east through the evening, but confidence is
high that MVFR and eventually IFR conditions will redevelop
most everywhere tonight with some fog also likely. VLIFR is
certainly possible, but confidence in its duration is poor. Drier
NNW winds arrive by mid/late morning behind a weak FROPA will
deliver VFR levels region wide.
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 57 75 47 67 55 / 10 0 0 0 0
Victoria 56 70 41 66 47 / 40 0 0 0 0
Laredo 51 77 47 69 54 / 0 0 0 0 0
Alice 54 77 44 71 52 / 10 0 0 0 0
Rockport 60 71 50 66 56 / 30 0 0 0 0
Cotulla 49 77 43 70 49 / 0 0 0 0 0
Kingsville 56 78 45 71 54 / 10 0 0 0 0
Navy Corpus 59 72 51 66 59 / 20 0 0 0 0
TX...Coastal Flood Advisory until 9 PM CST this evening For the
following zones: Aransas Islands...Calhoun Islands...
Kleberg Islands...Nueces Islands.
GM...Small Craft Advisory until 8 AM CST Thursday For the following
zones: Waters from Baffin Bay to Port Aransas from 20 to 60
NM...Waters from Port Aransas to Matagorda Ship Channel
from 20 to 60 NM.
Small Craft Advisory until 1 AM CST Thursday For the following
zones: Coastal waters from Baffin Bay to Port Aransas out
20 NM...Coastal waters from Port Aransas to Matagorda Ship
Channel out 20 NM.
Area Forecast Discussion
National Weather Service Fort Worth TX
621 PM CST Wed Jan 22 2020
.SHORT TERM... /NEW/
/Through Thursday evening/
North Texas finds itself in a little break in the rain this
evening, while patchy light rain and drizzle continue across
Central Texas. Surface analysis shows a 1005 mb low centered over
the Texas Panhandle, with a warm front extending to the southeast
along a line from Childress to Waco to Huntsville. A cold front
extends to the southwest of the surface low from Lubbock to
Artesia, NM to Deming, NM. Temperatures are in the 40s north of
the warm front, with temperatures in the 50s and dewpoints in the
upper 40s south of the warm front.
As the aforementioned warm front lifts north, the increasing warm
and moist air advection combined with light winds should allow for
widespread fog to develop. While the most favorable corridor for
fog development looks to be the I-35 corridor, pretty much the
entire CWA is fair game, with visibility likely to deteriorate
after 10 p.m. this evening. With this in mind, we will issue a
Dense Fog Advisory for the entirety of the CWA, valid through 9:00
a.m. Thursday morning. That being said, we will probably be able
to cancel some counties (particularly out west) from the advisory
as the early morning hours progress, and the cold front passage
allows visibility to improve.
Late tonight, the surface low will shift west, pulling the cold
front across North and Central Texas. Despite limited instability,
strong forcing from the surface cold front and steep mid-level
lapse rates in excess of 7 C/km should allow a few thunderstorms
to develop. High-resolution model guidance from the HREF and
time-lagged HRRR ensemble both pinpoint the Dallas/Fort Worth
Metropolitan Area and points northeast as the most likely area for
any thunderstorms. This thunderstorm activity would be most
likely from about 3 a.m. to 8 a.m. Any thunderstorms that do
develop should remain below severe limits.
Following the frontal passage, winds will shift out of the
northwest at around 10 mph. Cold air advection and persistent
cloud cover should keep highs in the 50s for much of the day. A
few spots could approach 60 F in our western counties though where
the sun may break out by early afternoon. Conversely, our eastern
counties may struggle to get much above the low 50s where cloud
cover is more persistent. Nevertheless, cloud cover should
decrease slowly from west to east as the day progresses.
.LONG TERM... /Issued 340 PM CST Wed Jan 22 2020/
/Thursday Night through Wednesday/
The strong upper disturbance responsible for the rain and drizzle
today will be departing the area by Thursday evening. Any
lingering cloud cover over the eastern counties will continue to
push east through the night allowing temperatures to fall into the
mid and upper 30s areawide by early Friday morning. Surface high
pressure building into North Texas beneath a passing shortwave
ridge will result in a rather nice Friday afternoon with highs
topping out in the low to mid 60s under sunny skies. The cloud
free skies will be short lived though as moisture will begin to
spread back across the region on Saturday. A pair of mid level
disturbances, one in the Southern Plains and one moving through
northern Mexico, will result in an increase in mid and high level
cloud cover through the day. Saturday should be a dry day with
highs in the mid 60s, but by late evening as stronger forcing for
ascent from the Plains shortwave arrives, we should see some
scattered showers begin to develop. Right now, it looks like a
quick shot at rain chances mainly across the eastern half of the
This disturbance moves by quickly and skies should begin to clear
out again by late Sunday. Yet another strong upstream shortwave
will begin to dig across the western U.S early next week. We`ll
see additional rain chances overspread the region by Tuesday.
Latest model guidance has shifted the axis of heavier
precipitation a little farther east, so we`ll continue to refine
these mid week PoPs over the coming days.
Concerns: LIFR FG likely overnight. Isolated to scattered TS
possible near Metroplex terminals. FROPA around daybreak.
CIGs remain IFR this evening, though vsby has improved somewhat.
Expect vsby to decrease markedly after 04Z as widespread FG
develops. CIGs/vsby should drop to LIFR late tonight, with vsby
below 1/4SM and VV below 200 ft possible at times. Isolated to
scattered TS may develop ahead of cold front after 06Z, mainly
across North Texas. While direct impacts at area terminals are
uncertain, confidence in TS development is high enough to include
VCTS at northern Metroplex terminals (i.e. all except KGKY).
FROPA is expected around 12Z, which should allow FG to dissipate,
and TS chances to end. Winds will veer out of the NW at around 10
KT. VFR should return by late afternoon (Metroplex) or early
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 42 55 40 61 42 / 60 5 0 0 0
Waco 46 55 38 63 40 / 30 0 0 0 0
Paris 36 48 36 54 36 / 90 40 0 0 0
Denton 41 54 38 60 40 / 60 0 0 0 0
McKinney 41 52 38 59 39 / 70 5 0 0 0
Dallas 42 53 40 61 41 / 60 5 0 0 0
Terrell 42 51 38 60 38 / 70 10 0 0 0
Corsicana 44 52 39 61 41 / 70 5 0 0 0
Temple 47 58 39 63 41 / 30 0 0 0 0
Mineral Wells 44 58 36 62 40 / 20 0 0 0 0
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
925 PM CST Wed Jan 22 2020
915 PM CST
The going forecast is largely in good shape, although have made a
few alterations to the near-term grids based on some evolving
observational and model trends.
Evening RAOB data from around the area indicates that the low-mid
levels continued to saturate from the top-down, with some nice
trends being captured by both a special 20z and standard 00z
sounding out of DVN. Haven`t seen any reports of precipitation
making it to the surface across our immediate CWA, but expect that
this will be changing quickly as the atmospheric column continues
to saturate down to and just under 850 mb. There seem to be two
distinct areas of dynamics at play, one of mainly mid-level DCVA
to our west and the other in the form of increasing jet dynamics
out of central Illinois. Based on the orientation of the latter,
have smeared high PoPs a bit farther to the east to encompass more
of our CWA east and south of the I-55/57 corridors. Also have been
noting quite a few mPING reports of sleet across central
Illinois...not all that surprising given the stubborn low-level
dry air and likely some degree of sublimation going on before
hydrometeors are making it to the surface. Do think this potential
will be relatively short-lived as the column more completely
saturates with light snowfall dominating and as such, have opted
to leave any sleet/ice pellet mention out of the gridded forecast
Based on upstream snowfall and liquid equivalent measurements, it
looks like snow to liquid ratios of about 7-9:1 roughly
characterize the nature of the ongoing snowfall, and have adjusted
the near-term grids closer to these values. That said, have also
nudged QPF values up a hair based on receipt of early-evening
model guidance, which has had the effect of ever so slightly
increasing snowfall amounts through Thursday morning to closer to
one inch and locally higher. Still looks like there may be a lull
in activity sometime towards Thursday afternoon before the next
slug of warm advection pushes in Thursday evening and overnight
into Friday. Updated products have been transmitted.
213 PM CST
The primary forecast message for this prolonged light wintry
event had only slight refinement with honing in on details
especially through Thursday. The confidence remains fairly high
that impacts will be limited through all of Thursday and into
Friday morning with this event. There likely will be lulls or
even periods of mixing with drizzle or a brief light rain, which
will prevent much for any accumulation during that time. For the
second portion of this event, Friday afternoon into early
Saturday, there remains greater uncertainty on some of the
specifics but moderate snow rates and more efficient accumulation
remain plausible. All in all this does not look like a winter
storm by either definition or by impacts, but with light snow
fairly frequent for portions of the CWA over the upcoming 60
hours, there will be at least some impacts and some challenges to
Focus through tonight has been on the onset time of light snow.
Satellite water vapor imagery indicates multiple short waves
across the central United States. These are all part of a
developing larger trough (eventual closed low) forced by a digging
jet stream maximum now moving into the Pacific northwest. A
fairly large area of wintry precipitation extends across Missouri
and Iowa and into Wisconsin. This is slowly inching eastward and
various satellite bands show clouds starting to thicken just west
of the region, indicative of more ascent and saturation. The
multiple waves right now have resulted in pockets of ascent and
broader snow to the west, with some freezing drizzle in-between.
As the forcing improves for a broader area of moisture transport
and isentropic ascent at the low-level jet height, would expect
that light snow will become prevailing upstream, possibly with
some pockets of moderate snow. This will creep into north central
Illinois this evening before a more rapid expansion across the
rest of the Illinois CWA into overnight, as forecast on RAP and
NAM isentropic surfaces. Northwest Indiana will be on the edge of
the deeper saturation, thanks to marginally moist air upstream
from that area, so light snow looks to onset there closer to
sunrise or even a little after.
This snow looks to be primarily minimal in impact, not only
because of timing but because of intensity being primarily light.
That said, precipitable waters of 0.6 inches and the broad forcing
should keep snow consistently falling once it starts into
Thursday morning. With it onsetting during the night and following
the recent cold, untreated pavement temperatures will be cold
enough for the light snow to accumulate. This will lead to some
impacts to the morning commute, with snow totals through mid-
morning forecast to be one half inch to one and a half inches
(highest north and west).
330 PM CST
Thursday through Wednesday...
Thursday through Saturday:
Stepping forward from the short term discussion, confidence is
high in falling precipitation for most of the CWA except perhaps
the far southeast through mid day Thursday, with aforementioned
generally broad WAA/isentropic ascent. Thermal profiles support
snow as p-type during this time, though of the lower ration/wetter
type. Temperatures will inch upward slightly amidst modest
southerly boundary layer flow to within a degree or two of 32F.
Additional snow amounts on colder surfaces Thursday morning of a
few tenths to locally near one inch are forecast.
Continue to suspect that road impacts through early Thursday PM
will be mitigated by temperatures being near to slightly above
freezing and the primarily light snowfall rates, with slick spots
more likely on untreated, elevated, or less traveled roads. During
Thursday afternoon, and possibly bridging the early evening with
northward extent, there is a signal (12z HREF 1-hr QPF as a proxy)
for a weakening of forcing that could yield a lull from already
light precip rates. Depending on surface temps, could potentially
see light rain mixing in with the snow, and overall minimal if any
additional snow. Consensus of model forecast soundings suggest
that saturation of ice nucleation layer should remain sufficient
to preclude any drizzle becoming a prevalent p-type. While impacts
to the Thursday morning commute are not expected to be significant,
latest trends suggest that Thursday PM commute will be even less
so, as additional snow would be a dusting/coating to perhaps a few
tenths, if that.
Focus Thursday night through Friday night and possibly into
Saturday morning centers on the additional rounds of light to
occasionally moderate precipitation from closed upper level low
pressure gradually tracking east-northeastward. With persistent
low clouds and rounds of precipitation, the diurnal temperature
range through Saturday will be exceptionally low (2-4F or less).
Favored precipitation type for a good chunk of the CWA much of
this time is wet snow, however a flip to rain is a decent
possibility southeast of I-55 on Friday. Finally, depending on the
exact position and strength of the closed mid-upper low and
associated 850 mb and 925 mb lows, there may be enough warm air
aloft for melting while 2m temps are near freezing for a chance
for spotty freezing rain south of IL and Kankakee Rivers late
Thursday night into Friday morning.
There was a slight northward and a bit stronger trend with the
closed low among the 12z guidance, and a bit farther north with
associated weak surface low through Friday night. That said, 12km
NAM was a notably stronger and farther northwest with key
features, including 925 mb low center, resulting in much warmer
air aloft at 925 mb advecting in from the southeast Thursday night
into Friday. This forecast was leaned toward the ECMWF (and
similar 12z CMC thermal profiles), which has had good run to run
consistency and strong ensemble clustering. Regarding thermal
profiles, the uniformly just above freezing layer at 925 mb over
the CWA repeated on multiple runs of the operational GFS has had
minimal support from the rest of the guidance, including the GEFS.
Therefore, have continued to lean away from this idea.
The next round of more steady precipitation rates will evolve
mid-late Thursday evening into Friday morning as the closed low
and surface low approach and cross the MS River near or south of
STL. Increase in large scale ascent and developing trowal feature
will blossom area of precip northward, all snow CWA at least
initially, with strength of mass fields determining whether a warm
layer aloft spreads into southern CWA and introduces any chance
for light freezing rain. Confidence in this aspect of the forecast
is low. Message for the Friday morning commute is similar to that
of Thursday morning`s, with ongoing snow and additional light
accumulations of up to 1-2", except an inch or less far southeast.
Wet snow, primarily light rates, and near to a bit above freezing
temps again seem to point toward road impacts being more likely
on untreated, elevated, or less traveled roads.
Uncertainty increases the rest of Friday into Saturday morning,
owing to the inherent uncertainty in correctly modeling the
strength, exact track, and timing of a large closed low
circulation. In short, a stronger and farther north track would
bring warm air farther northwest into the CWA, and also possible
loss of ice presence in DGZ from mid-level dry-slot impingement.
At still about two days out, deferred any potential for transition
to drizzle as p-type, especially south, for later updates. Leaned
toward colder guidance for temperatures in anticipation of
extremely small diurnal range. Precipitation type could oscillate
between rain and snow at times of lighter precip (and flip to rain
at least southeast of I-55 depending on how mild it gets).
Main time period of interest for a potentially more impactful
round of snow is later Friday afternoon through Friday night. The
closed low and surface low may actually slow its forward progress
just to our east, putting portions of northern Illinois in line
for several hours of deformation area snow with more sustained
steady light to moderate rates. Additional snow amounts of up to
2-4" will be possible, with current official gridded forecast
placing this zone near and north of I-88. Depending on how this
all plays out, Friday PM through early Saturday AM may have best
chance for portions of our area needing a winter weather advisory.
With possibility of further slowing of the system, light snow may
continue deeper into Saturday morning, if not the afternoon
hours. We continue to message this event in multiple parts, as the
incremental snowfall accumulations over the next few days will
likely be a good bit higher than the net accums when accounting
for melting, compaction and any mix or transition to rain.
Saturday Night through Wednesday:
For the remainder of the weekend into the middle of next
week a very gradual warming trend appears likely, with highs each
day in the 35 to 40 degree range for most locations, maybe a bit
warmer south, and lows about ten degrees above seasonal norms.
Winds also will be relatively light through this period.
Considering this falls in the latter half of our climatologically
coldest part of the year, the situation could be much worse.
On the heels of the departing low, with continued cloudiness plus
northwesterly flow at the surface and aloft, Sunday looks to be the
coolest day of the period. Flow off the lake may support some
slight rain or snow chances Saturday night in Indiana but otherwise
precip chances appear very low at least through Tuesday afternoon or
evening. Models do show a sheared out upper wave sliding through
sometime on Monday ahead of an approaching ridge, along with a weak
surface frontal zone, but moisture presently appears too limited to
support more than ongoing cloudiness.
By Tuesday, models are in reasonable agreement in pushing the upper
ridge axis to our east and developing a well organized low over the
southern Plains. Warm advection precip ahead of this system could
reach the area by late Tuesday, and surface temperature trends as
well as the track of the low will determine whether this falls as
rain, snow, or a transition.
By Wednesday there is considerable disagreement on the eventual
speed and direction of the low track. This is reflected in the
deterministic runs but also in the ensembles where there is enough
disagreement that the surface and upper lows are not even diagnosed
as areas of focused circulation. Confidence is therefore low on
the potential significance for this area.
For the 00Z TAFs...
Conditions are expected to rapidly deteriorate during the early
overnight hours as an upper-level low nears the region. Ceilings
will quickly lower late this evening, followed shortly by the onset
of -SN. Visibility may vary in the IFR range for a couple hours at
onset, but increased moisture and a low-level trough will allow for
a period of higher intensity and more coverage late tonight, roughly
in the 09-12Z window. Visibility will likely be low-end IFR while
ceilings lower into low-end MVFR or potentially high-end IFR.
Precip may lessen slightly in intensity, but ceilings will continue
to lower as the upper low continues to near. This trend will likely
continue through the day, with low-end IFR ceilings and visibility
continuing through the day. Additionally, a wind shift from around
180 to 160 degrees is appearing more likely to occur around 12Z.
Winds may briefly veer back to around 180 degrees for a few hours
later in the morning, but continue to settle into a SE direction by
There is some concern based off upstream trends, guidance, and
pattern recognition that ceilings and/or visibility may be lower than
currently forecast late Thursday morning through the afternoon, with
the potential for some sporadic LIFR ceilings and visibility (due to
While precip will likely remain -SN through Thursday afternoon, some
drizzle may begin to mix in with the SN as early as Thursday
afternoon. However, -SN would remain the primary precip type through
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Area Forecast Discussion
National Weather Service Springfield MO
553 PM CST Wed Jan 22 2020
Issued at 240 PM CST Wed Jan 22 2020
The main forecasting challenges continue to be precipitation type
and travel impacts.
As of 21z (3 PM) all locations west of the US Highway 65 corridor
have warmed to above freezing with only rain being reported
across eastern Kansas and western Missouri. On the contrary,
locations along and east of Highway 65 continue reading
temperatures in the 30-32 degree range and will remain in that
range overnight. Thus, the Winter Weather Advisory will remain in
effect until 18z (Noon) on Thursday for locations east of Highway
65 where a wintry mix and light wintry accumulation is
.SHORT TERM...(This evening through Friday)
Issued at 240 PM CST Wed Jan 22 2020
Integrated water vapor transport continues to depict a modest
plume of low-level moisture coming in from the Gulf of Mexico
ahead of an upper-level longwave trough. The RAP model is
indicating precipitable water (PWAT) values near 0.8, which is in
the 90th percentile for available moisture for this time of year.
Large scale synoptic lift ahead of the incoming trough and low-
level isentropic lift coming up from the south are combining with
this available moisture to help produce a swath of light
precipitation across southwest Missouri.
Thermal profiles are indicating a period of wintry precipitation
this evening into Thursday across the eastern Ozarks, with sleet
perhaps becoming the dominant precip type overnight. Light
accumulation is expected, and while many road temperatures have
warmed into the upper 30s this afternoon, minor impacts to
roadways are anticipated. This will especially be the case in the
higher terrain locations of the eastern Ozarks (northern Douglas
and southern Webster and Wright counties) along HWY 60. There,
sleet and snow accumulation will range between a trace and two
inches. Elsewhere across the eastern Ozarks, sleet and snow will
accumulate between a trace and one half inch with a thin glaze of
ice as well. Bottom line: locations along and east of HWY 65 will
stand the best chance for wintry weather tonight, with minor road
impacts anticipated ahead of Thursday morning`s commute.
By Thursday afternoon, the low-level temperature profile will
become warm enough such that all of southwest Missouri and eastern
Kansas transitions to plain rain. This will put an end to the
current Winter Weather Advisory.
By Thursday evening, an amplified shortwave trough will dig into
central Missouri in response to a 100+ kt 300-mb jet max diving
across the Central Plains. This shortwave will become closed off,
which will allow for dynamic cooling to occur, which will
ultimately cool the thermal profile from the top down. This
phenomenon will allow rain to transition back to snow Thursday
evening into Friday morning. During this period, light snow will
likely accumulate on grassy surfaces with between a dusting and
two inches possible in locations north of HWY 60 (the higher of
which will fall over central Missouri). A new Winter Weather
Advisory may be needed for this timeframe ahead of Friday
morning`s commute, but we will let the overnight crew better
assess that decision.
Light snow will end from west to east during the day on Friday as
the upper-level closed low lifts out of central Missouri and into
the Great Lakes Region.
.LONG TERM...(Saturday through Wednesday)
Issued at 240 PM CST Wed Jan 22 2020
Saturday through Tuesday will mark a less active period across the
region as a broad ridge builds across the western CONUS and
surface high pressure slides into the Central Plains. The pattern
during this timeframe will feature seasonal temperatures - daily
highs 45-50 degrees with overnight lows 30-35 degrees.
Both medium range deterministic guidance and GEFS/EC ensembles
show another shortwave trough digging across the Rockies by
Tuesday evening, with yet another multi-dimensional weather system
spinning up over the Southern Plains and into our region.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 543 PM CST Wed Jan 22 2020
IFR will remain likely through much of Thursday as a slow moving
storm system continues to impact the region. A light wintry mix of
precipitation will fall around Springfield, including freezing
rain and sleet tonight, with a higher probability of snow by
Thursday afternoon. Rain will be the main precipitation type at
Joplin and Branson.
Low level wind shear conditions will persist tonight along with
brisk south to southeast surface winds. The winds will then turn
around to the west by later Thursday afternoon as a cold front
moves through southern Missouri.
MO...Winter Weather Advisory until noon CST Thursday for MOZ055>058-