Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/06/22
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
927 PM EST Sat Mar 5 2022
.SYNOPSIS...
Low pressure tracks north of the area on Sunday, and could
bring a brief mix of snow or freezing rain to inland areas
Sunday morning. Rain showers expected for most of Sunday, with
rain changing to snow showers in the mountains Sunday night.
Another low could bring a period of rain, possibly changing to
snow Monday night. Mild high pressure builds in for the middle
of next week. Another round of precipitation is possible late in
the week as low pressure crosses over the Great Lakes.
&&
.NEAR TERM /THROUGH SUNDAY/...
925 PM Update: Have boosted temperatures given evening trends
showing some locations struggling to fall much as cloud cover
increases. Top down saturation continues as evidenced by recent
observation of very light snow on the summit of Mount Washington
though with significant dewpoint depressions for valley
locations and ample llevel dry air on the 00Z GYX RAOB. Updated
PoP progression through the overnight with latest mesoscale
model trends...but no significant change to the flavor of the
forecast. Expect any freezing precip potential to hold off until
towards daybreak when the boundary layer will finally saturate.
See no need to make alterations to the WSW or SPS as advisory
area continues to be best positioned for freezing rain profiles
AND measurable precipitation.
620 PM Update: Dry airmass is very slowly moistening this
hour...both top down and gradually in the boundary layer.
However...dewpoints have been pretty slow to respond while
surface temperatures remain a few degrees above the going
forecast. Brought near term forecast into alignment with these
trends with no other substantial changes to the forecast.
Previous Discussion below...
Tonight is relatively quiet compared to the rest of the first
36 hours of the forecast. High clouds continue to filter into
the area and will gradually thicken and lower overnight.
This...along with WAA will help to keep temps fairly steady and
not bitterly cold tonight. Current thinking is that dry low
levels will prevent much in the way of precip overnight and so I
keep PoP mainly isolated to scattered into the higher terrain.
Wet bulb cooling should also help to keep ptype snow at least
until Sun morning.
&&
.SHORT TERM /SUNDAY NIGHT/...
The strongest WAA forcing arrives Sun morning...and this is
likely when the greatest coverage of precip will be before the
warm front lifts north and mostly out of the forecast area.
Model guidance has pretty aggressive warming early in the
day...but we know how that goes locally...so I have kept cold
temps wedged into the terrain thru early afternoon. As a result
there will be some freezing rain Sun morning into midday.
Amounts are very light...but there is enough coverage and
potential for slick spots in western ME that I have issued a
winter weather advisory for freezing rain. In White Mtns and
into the Pemi Valley there may be enough pockets of colder air
that localized icing is possible. I have issued a SPS for those
zones where coverage is just too local for an advisory.
Needless to say temp trends are coldest early with steady
warming thru the day and into the evening as WAA continues. Some
areas that can truly break out into the warm sector will have
the potential to top 60 degrees...while interior western ME may
be looking at 39 at best.
CAM guidance is interesting late Sun as the cold front enters
the forecast area from the northwest. To varying degrees they
initiate some convection along the front...with the 05.12z and
05.18z HRRR being very aggressive with a broken line across much
of the forecast area. SPC even has a marginal risk just clipping
the CT River Valley. I am skeptical that we will be able to mix
out the inversion enough for surface based convection across
much of the forecast area...but enough elevated instability is
forecast that I added some thunder around 7 pm. These showers
and thunderstorms will move southeastward and weaken with time
as the cold front starts to stall. Ahead of the front winds
aloft will be moderately strong...but given their orientation
parallel to the coast I think any stronger gusts will confined
to very near the water.
Temps remain mild overnight and the cold front likely waits
until Mon to fully mix down.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
The extended portion of the forecast remains relatively active
for the upcoming week. On Monday, low pressure will race
northeast as a short wave is ejected in a fast southwesterly
flow aloft. There will be sufficient moisture as well as a brief
period of warm air advection to allow for rain chances to
increase during the day. Temperature profiles suggest warming
conditions at the surface and aloft will lead to rain over
southern areas while a rain and snow mix develop over the north.
GYX probability plots suggest a changeover to snow across
portions of the north Monday evening as the system exits the
region and cold air advection begins. A light coating of snow
remains possible over southern areas due to the possibility of a
brief period of rain and snow mix.
Upslope northwesterly winds can be expected on Tuesday as high
pressure builds towards the Northeast. This will allow for cloud
cover in the north as well as a slight chance for snow showers.
Downwind of the mountains, mainly sunny conditions will allow
for temperatures to climb into the lower 40s for afternoon
highs.
As the surface ridge crests over New England Tuesday night,
temperatures will quickly drop allowing for the potential of
some slick spots on secondary roads. Overnight temperatures will
drop into the single numbers in the north and teens to mid 20s
in the south.
Dry and mild conditions will continue for Wednesday with
temperatures climbing well into the 40s by Thursday as the
atmosphere continues to moderate over the region under a weak
flow aloft. We will continue to monitor low pressure passing
well south of the region and off the coast Wednesday evening
potentially bringing clouds to southern portions of the region
for a brief period of time.
There is considerable uncertainty late in the week as low
pressure, potentially crosses near or over the Great Lakes and
into Canada. This lack of clarity shows up well in the model
ensembles with some members indicating precipitation and light
snow and rain at the onset, while others are completely dry.
Despite persistent troughing indicated over the region, this
system appears to be sufficiently progressive to minimize the
chance for heavy precipitation. Will continue to monitor for
this system and the potential for a secondary area of low
pressure to develop along the East Coast late in the work week.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Short Term...
Summary: Low pressure moving north of the region tonight will lift a
warm front across the area through Sunday before a cold front
approaches Sunday evening...crossing the area Sunday night.
Restrictions: VFR all sites at the moment. Rapid deterioration to
IFR/low MVFR is expected in stratus and some fog around daybreak
Sunday. There is some potential for a bit of freezing drizzle or
light freezing rain at AUG during the morning hours Sunday. By late
morning and through the early to mid afternoon a period of rain
showers is likely throughout the terminals...but this will actually
cause CIGS and VSBYS to lift with improvement to VFR by late
afternoon/evening. A band of showers will make a run towards
HIE/LEB right at the very end of the TAF period. If this
occurs...there is the potential for an isolated thunderstorm with
MVFR /localized IFR/ restrictions. Otherwise...VFR Sunday night.
Winds: Light southerly winds overnight /less than 10kts/...become
southwesterly 5-10kts Sunday morning and increase to 12g22kts Sunday
afternoon and evening before shifting west 10-15kts Sunday night.
LLWS: 2kft Southwesterly winds increase to 35-45kts by daybreak
Sunday and continue through the day...strengthening to 40-50kts
Sunday night.
Snowfall Rates and Character: While a few snowflakes are possible
around midnight in the mountains...no accumulations are
expected.
Long Term...VFR conditions expected Monday morning followed by
IFR conditions in rain and any snow to the north by late morning
and midday hours. Will see improving condition on Tuesday with
VFR conditions. The exception will be the mountains where
upslope cloudiness will lead to a few possible light snow
showers and MVFR conditions. VFR conditions expected for most of
the region Wednesday through Thursday before lowering ceiling
arrive with an approaching system late in the work week.
&&
.MARINE...
Short Term...Southwesterly winds are still expected to increase
tonight and especially Sun. Low end gales are likely outside of
the bays into Sun night. SCA conditions for all other waters
also thru Sun night. Winds and seas will diminish rather quickly
into Mon morning. A gale warning has been issued outside of the
bays...and a SCA in Casco and Penobscot Bays.
Long Term...SCA conditions can be expected Monday and Tuesday as
low pressure crosses the region, followed by winds backing from
southwest to northwest with time. Much more quiet conditions
expected Wednesday and Thursday before low pressure approaches
the Northeast late in the work week.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory from 7 AM to 2 PM EST Sunday for
MEZ007>009.
NH...None.
MARINE...Small Craft Advisory from 1 PM Sunday to 4 AM EST Monday for
ANZ151-153.
Gale Warning from 1 PM Sunday to 4 AM EST Monday for ANZ150-
152-154.
&&
$$
NEAR TERM UPDATE...Arnott
Area Forecast Discussion
National Weather Service Lincoln IL
851 PM CST Sat Mar 5 2022
.SYNOPSIS...
Issued at 157 PM CST Sat Mar 5 2022
A pair of frontal systems will bring adverse weather conditions
to central Illinois tonight through Monday. Then, after a quiet
mid- week period, another frontal system will lift across the
region late Thursday into Friday, bringing accumulating snow and
much colder temperatures.
&&
.UPDATE...
Issued at 851 PM CST Sat Mar 5 2022
Needed to make some adjustments to the forecast pops/wx to account
for the severe thunderstorm watch that just came out and the
timing of precip across the CWA. HiRes HRRR seems to be doing the
best job with the pregression of the line of storms so followed
that closely. Update to the grids and the forecast have been sent,
along with the watch notification message.
&&
.SHORT TERM...(Tonight)
ISSUED AT 157 PM CST Sat Mar 5 2022
Wind Advisory:
We`ve expanded the Wind Advisory southward to I-70, with the
following support plucked from the latest suite of 12z guidance:
(1) pressure falls occurring this evening in the vicinity of a
deepening surface low, (2) scattered convection out ahead of the
main front helping to tap into a robust LLJ, (3) steep low-level
lapse rates and sufficient mixing in the immediate wake of the
cold front, (4) latest HREF 10m mean gusts suggest 45+ mph across
much of the region, and (5) over 50% of GFS ensemble guidance is
meeting or exceeding Wind Advisory criteria as far south as I-70.
Convective Trends:
Clouds continue to break for sunshine this afternoon across a
broad warm sector. Despite this, mesoscale soundings continue to
maintain a stubborn capping inversion ahead of the cold front.
This should keep any pre-frontal convective activity "elevated"
until the cold front helps parcels become surface-based later
tonight.
Short-term, hi-res guidance continues to struggle in resolving
convection for this evening, with some solutions suggesting 2
distinct lines pushing across central Illinois. This seems
unlikely, as we will likely need more theta-e juiced into this
air mass to support 2 organized lines of successive convection.
At this point, we are putting more weight toward convection tied
to the cold front, where forcing, kinematics, and low-level CAPE
will be most favorable to support organized convection. A few
pockets of damaging straight-line winds will be possible late
tonight, especially wherever the system cold pool becomes
balanced or slightly shear dominant. The orientation and strength
of the 0-3 km shear vectors will be key in assessing where these
pockets of enhanced thunderstorm winds may develop. It`s
important to note that the tornado threat, while low, is non-
zero. As an educated guess, locations along and north of I-70
stand the best chance at severe weather tonight, with all
aggregate hazards becoming less likely the further south you get
from the better upper dynamics.
If elevated, pre-frontal convection develops this evening on the
nose of the LLJ, it would likely stabilize the environment enough
to limit storm development along the cold front. In this
scenario, there could be some isolated downburst signatures that
exceed severe limits. Small hail could also accompany the taller
updrafts of any elevated storms.
Bottom line, it`s not clear yet which of the convection will
become more dominant-- pre-frontal or frontal. Regardless, severe
thunderstorm wind damage has the highest potential this evening
across central Illinois for locations north of I-70, mainly
between 01z/7pm and 06z/Midnight.
.LONG TERM...(Next Week)
ISSUED AT 157 PM CST Sat Mar 5 2022
Winds will quickly diminish Sunday morning in response to the
departing mid-level shortwave and surface low. Most locations
across central Illinois will see some sun during the morning hours
as a ridge of high pressure quickly builds across the region.
Yet, temperatures will be markedly cooler in the wake of frontal
passage. Afternoon highs will be 10-20 degrees cooler than the
previous 24 hrs, with temperatures warming into the low-to-mid
50s.
Clouds will be on the increase Sunday evening as a mid-level
shortwave trough and its attendant surface low pivot across the
southern Plains and lift toward the Ohio River Valley. A
moisture-laden air mass will surge northward ahead of this
disturbance with mid 50s surface dewpoints pooling along a
sharpening baroclinic zone that stalls just south of the I-70
corridor. Overrunning/isentropic processes north of the front,
and deep moist ascent along the front should allow moderate- to-
heavy rain to develop across much of central and southern
Illinois. To give further perspective as to how saturated this
air mass will be, PWAT values are expected to exceed the 99th
percentile of climatology.
Latest QPF from WPC supports between 0.5" -1.00" north of I-72
through Monday morning, and between 1-2" south of I-72. This is in
good agreement with the latest 12z HREF, but its LPMM methodology
suggests a narrow corridor of 2-3" somewhere along the I-70
corridor where frontogenesis becomes enhanced within the
baroclinic zone.
The heavy rainfall episode that develops Sunday night into Monday
will renew flood concerns across central and southern Illinois,
and this is highlighted in WPC`s latest Excessive Rainfall
Outlook.
A brief changeover to snow is possible Monday morning mainly
north of a Beardstown to Bloomington line where thermal profiles
turn colder. Up to an inch of snowfall is possible from the Quad
Cities into north central Illinois. Lesser amounts are expected
south of there across central Illinois. Little or no winter-
weather impact is expected.
Dry and calm conditions will return Tuesday into Thursday as
temperatures exhibit a warming trend ahead of the next frontal
system. By Thursday night, the Polar Jet Stream looks to buckle
over the Rockies as a mid-level shortwave trough begins to dig
hard across the Northern Plains. This will drive an arctic front
into the Midwest, bringing accumulating snow and a return to very
cold temperatures to central Illinois by Friday.
Overnight temperatures next weekend could bottom out in the
single digits, per the latest NBM guidance. Zoinks.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 556 PM CST Sat Mar 5 2022
Lower clouds around 5-6kft are increasing across the area this
evening ahead of two lines of precipitation. The first line will
start soon, but just be light rain or rain showers, so just have
VCSH at all sites. Then the line of storms is expected this
evening, starting at 03-05z and ending 2hrs later. Vis will be low
around 3sm due to the blowing of the rain, but believe cigs will
remain above 3kft. Some cigs around 3.5kft will continue for a
several hours after the precip ends, and the scatter out
overnight. Expecting more scattered clouds at PIA and BMI since
they will be closer to the track of the wrap around clouds with
the low, with just cirrus at SPI, DEC, and CMI. This will be the
rule through tomorrow. Winds will be gusty out of the south, then
southwest, then turning west once the front goes through in the
early morning hours. Gusts of 40-45kts will be common through the
night and into overnight, but then decrease late tonight through
tomorrow.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM CST Sunday for ILZ027>031-036>038-
040>057-061.
&&
$$
UPDATE...Auten
SYNOPSIS...MJA
SHORT TERM...MJA
LONG TERM...MJA
AVIATION...Auten
Area Forecast Discussion
National Weather Service Louisville KY
933 PM EST Sat Mar 5 2022
.Forecast Update...
Issued at 920 PM EST Sat Mar 5 2022
Fairly extensive mid-level cloud deck and steady south winds are
keeping temperatures unseasonably mild this evening. While it`s
quite possible that we`ll only drop a few degrees overnight, will
not raise mins at this time because with dewpoints in the 50s, all
it will take is a brief shower to drop the temp to (or even below)
the forecast lows. Will initialize with lighter winds to match up
with the most recent obs, but otherwise the current forecast is in
good shape.
Did collaborate with PAH regarding Sunday rainfall, which could
get heavy at times along or a bit north of a Bowling Green to
Lexington line. However, opted not to go with a Flood Watch at
this time, as any training supportive of flash flooding would have
to be quite narrowly focused. Overnight crew will want to revisit
when 00Z synoptic runs come in.
&&
.Short Term...(This evening through Sunday)
Issued at 315 PM EST Sat Mar 5 2022
Synoptic overview features deep troughing across the western US,
with a shortwave over the Central Plains. Underneath this shortwave,
sfc analysis finds two sfc lows, one over northeastern Kansas, and
another over northern Iowa, with a warm front extending into central
IN, and a cold front trailing through Nebraska and Kansas. We have
been located deep within the warm sector today, and underneath a
southerly 850mb jet of roughly 30kts. This has allowed for enough
mixing to result in sfc winds of 15-20 mph and gusts up to 35-40 mph
today, plenty of WAA to raise temps into the the low to mid 70s so
far today. Increasing cloud cover has put a damper on temps this
afternoon, which likely will keep temps a few degrees below the
previous forecast.
For tonight, the aforementioned LLJ will strengthen, with a core of
850mb winds expected to increase to near 50-60kts over the Ohio
Valley. The sfc low will continue a northeastward track towards the
Great Lakes, which will bring the trailing cold front closer to our
region. LLJ will pull plenty of moisture and warm air into our
region overnight, resulting in sfc dewpoints in the 50s and sfc
temperatures in the low 60s. Expect wind gusts of 25-35 mph
overnight. We could begin to see some isolated reflectivity returns
late tonight, though soundings reveal sfc dewpoint depressions of
nearly 20 degrees through the overnight. It`s not until closer to 08-
10z Sunday that low level dewpoint depressions narrow, resulting in
better conditions for precip to make it to the sfc.
By Sunday morning, the aforementioned cold front will be approaching
the region from the northwest. We`ll likely see a line of precip
with embedded thunder along the cold front. Model soundings for
Sunday morning support elevated instability, so not too concerned
with severe threat during that time. As we get later into Sunday,
that cold front will sag southward into central Kentucky and then
stall out as a stationary boundary. The greatest vertical velocities
and moisture convergence will be along this stalled front, resulting
in the area of new convective concerns throughout the day. CAMs
continue to show storm motions parallel to the boundary, resulting
in training of showers and storms and a very narrow axis of higher
QPF, potentially 2+ inches over a 12 hour period. The RAP and HRRR
have been a bit more aggressive with instability in today`s runs,
where both suggest surface based instability reaching 1000 J/kg by
tomorrow afternoon. HREF mean SBCAPE suggests slightly less, in the
neighborhood of 500 J/kg. Sfc dewpoints will be reaching the low
60s, and possibly the mid 60s across south-central KY. Though lapse
rates are not too impressive, 40kts of bulk shear will be enough to
support an organization of convective storms south of the KY
Parkways. As mentioned in the previous discussion, any collision of
storms along the front will limit severe potential by hindering tall
updraft growth. Regardless, there still appears to be a potential
for a low-end severe threat mainly south of the Kentucky Parkways
for Sunday afternoon where temperatures may reach the mid 70s once
again. Towards the end of the short term period, the stalled frontal
boundary will begin a northward push.
.Long Term...(Sunday night through Saturday)
Issued at 250 PM EST Sat Mar 5 2022
Synopsis: Wet and breezy with local minor flooding and a few strong
storms possible to end the weekend and start the new week. The rest
of the week looks quieter with seasonable temperatures, followed by
a big cool-down next weekend. Don`t put the winter coats away yet!
Confidence: Confidence is high in widespread rain Sunday night into
Monday morning. Medium-high confidence in the possibility of locally
heavy rain. Low confidence in the chance of severe storms.
Sunday night-Monday: Low pressure over the Ozarks Sunday evening
will deepen and become better organized as it heads northeast into
Indiana by sunrise Monday, with its cold front trailing back to east
Texas. Evening showers and embedded thunderstorms will lift
northward with a relative lull in coverage during the late night
hours. Toward the pre-dawn hours showers and a few thunderstorms
will re-enter the region from the west along with new convection
developing over southern Indiana near the surface low and in 850mb
theta-e ridging with a plentiful moisture supply. Rainfall
efficiency should peak roughly in the 8-14Z time range Monday
morning with precipitable water values possibly topping 1.5" (+3sd).
The heaviest QPF looks to be from MO and IL through IN to OH, with
southern Indiana standing the best shot at significantly heavy rains
after midnight Sunday night into early Monday morning. Could see 1-
2" north of the Ohio River in a 9-12 hour period. 6hr FFG is
currently in the 2-3" range, though that could come down some
depending on how much falls late tonight through Sunday. We could
see some southwest-northeast training of showers/storms, and this is
likely what it will take to get localized flooding issues.
Soundings show a tall, thin, slightly elevated CAPE Sunday night
with only modest amounts of any mid-level dry air. Still, the
nocturnal inversion doesn`t look particularly strong and we`ll have
40-50kt winds at 0.5km as a strong low level jet cranks up from
Arkansas to Ohio. Can`t entirely rule out some gusty winds making it
down to the surface in any stronger convection.
On Monday the Indiana low will scoot quickly off to the eastern
Great Lakes and will pull its cold front through the middle Ohio
Valley primarily during the morning hours, accompanied by a band of
showers and a few storms. Surface-based instability still looks
quite meager. Very strong winds will continue just off the surface,
around 50kt at 1700 feet, so instability will be key to get robust
enough updrafts to allow convection to grow strong enough to bring
enhanced gusts down to the surface. The exact timing of the cold
frontal passage will be instrumental in this, since a slightly
slower fropa will allow more of a chance at destabilization. Shear
will be very strong with long, looping hodographs, so definitely
something to keep an eye on.
Heavy downpours can still be expected ahead of the cold front with
plenty of moisture in the column and surface dew points around 60.
Training should be somewhat less prevalent as the band of showers
will be more perpendicular to its forward movement.
After a warm morning, temperatures will fall Monday afternoon with
southern Indiana dropping into the mid and upper 40s by suppertime.
Monday night - Tuesday: High pressure over the Plains will translate
eastward into the Ohio Valley and provide us with dry weather and
seasonable temperatures.
Tuesday night - Wednesday: A weakening cold front will make a run at
us from the northwest while a much more significant system crosses
the southeast United States. The northern front will be dry. Models
have been consistent keeping the bulk of the southern system`s
precipitation just off to our south, but have shown a slight
northward trend recently so will hang on to small PoPs in southern
and eastern sections of central Kentucky. Any precipitation that
does fall would be in the form of a very light rain.
Wednesday night and beyond: After general WSW upper flow for most of
the week, a deep upper trough is expected to dive down into the U.S.
toward the weekend. Not surprisingly, guidance is showing different
solutions during this shift, leading to low forecast confidence.
Will hold on to some PoPs, though, as the system barrels in. There
is higher confidence that we will experience a significant cool down
next weekend, which is supported by CPC outlooks. Many locations
won`t make it out of the 30s on Saturday. Enjoy today`s 70s!
&&
.Aviation...(00Z TAF Issuance)
Issued at 650 PM EST Sat Mar 5 2022
VFR conditions will continue during the first half of tonight. Low-
level winds are poised to strengthen ahead of an approaching cold
front and cause LLWS once again at all terminals for the 06/03-09Z
interval, approximately. By the time of the cold front passage,
expect conditions to deteriorate as ceilings fall to MVFR.
Additionally, periods of moderate rain and isolated thunderstorms
are associated with the frontal activity. A couple of hours after
sunrise, expect MVFR ceilings to persistently fall below 2,000 feet
with winds still gusting. However, with the departure of the LLJ in
the afternoon, winds will slowly decrease and veer a few degrees to
the west-southwest.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...RAS
Short Term...CJP
Long Term...13
Aviation...ALL
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
551 PM CST Sat Mar 5 2022
.SHORT TERM... (Through Late Sunday Night)
Issued at 247 PM CST Sat Mar 5 2022
We have several potential weather threats through Sunday night:
1. Severe thunderstorm threat for this evening, mainly across parts
of northeast Missouri and west central Illinois.
2. Severe thunderstorm threat for Sunday evening for southeast
Missouri.
3. Heavy rain threat for areas along and southeast of I-44.
All of these potential threats are being caused by two short waves,
one of which is now moving northeast into Nebraska from northeast
Colorado. The surface reflection is also moving northeast, but is
farther to the east over the southeast corner of Nebraska/extreme
northwest Missouri. The system is dragging a dry line through
eastern Nebraska, and the cold front isn`t too far behind. Guidance
indicates that the cold front will catch up to the dry line over
western Missouri between 00-02Z tonight, and the front will continue
to push east-southeast through Sunday morning. Latest RAP runs show
a very respectable 1000-1800 J/Kg SBCAPE ahead of the front this
afternoon over Kansas and northwest Missouri. The convection well
out ahead of the front moving into central/north central Missouri
does not appear to be tapping into that instability and is likely
elevated and forced by warm advection. Short range guidance
including most CAMs shows a broken line of thunderstorms developing
along or just ahead of the cold front, and anchored to the strongest
instability. These storms move east-southeast with the front into
our central and northeast Missouri counties after 00Z...most likely
closer to 01-02Z. There is a decent capping inversion apparent on
forecast soundings and the plan-view CINH map from the RAP and GFS
show well over 100 J/Kg at the strongest, but a thin area of
relatively low CINH in the vicinity of the front (as low as 10-20
J/Kg). Think that as instability wanes due to loss of daytime
heating, the inversion will eventually kill the surface based
convection, and the low level flow will turn parallel to the
temperature gradient ahead of the front, so there will be little if
any isentropic lift to produce elevated convection. CAMs show this
slow process of weakening and dissipating storms taking place
through the late evening until there`s little but isolated showers
left along the front after 06Z. All that being said, thunderstorms
just ahead of the front tonight back over parts of central and
northeast Missouri into west central Illinois where instability will
remain strongest could potentially be severe with damaging winds and
a tornado or two being the primary threats.
The front will continue to sag south Sunday morning and finally
stall, extending from far northwest Arkansas through southeast
Missouri into extreme southern Illinois. Here`s when the next short
wave in line (which is currently over southern Nevada, will move
into the Plains, forcing cyclogenesis along the stalled baroclinic
zone over northern Texas/Oklahoma. This will increase the low level
southerly flow in the warm sector across the southeast Plains and
Lower Mississippi Valley. Short range guidance builds elevated
instability in the 500-1000 J/Kg range up into southeast Missouri
Sunday night on the nose of the low level jet. Unlike tonight, the
jet will be pointed almost perpendicular to the baroclinic zone, so
there will be plenty of forcing to generate convection. There will
once again be a small area of lower CINH across southeast Missouri
where a few storms may become briefly rooted in the boundary layer
and produce a few damaging wind gusts and even a tornado or two due
to the enhanced helicity in the vicinity of the surface boundary.
As we`ve been discussing for the past few days, P-Wats and IVT will
be anomalously high according to the NAEFS and GEFS, approaching the
99th percentile across the eastern Ozarks on Monday evening. With
these factors in their favor, the aforementioned thunderstorms on
Sunday night will have plenty of moisture to work with, and could
produce locally heavy rain. Latest QPF along and southeast of I-44
shows between 1.75 and 2 inches of rain falling during the 12 hours
between 00Z and 12Z Monday, mostly between 00Z and 06Z. Unless all
this rain falls within a 1 or 2 hour period, I continue to feel that
any flooding issues will be minor and isolated...confined to poor
drainage and low lying areas. Additionally, there is still well
more than 24 hours before any potential heavy rain causes issues, so
there`s plenty of time left to continue to evaluate the threat. We
will therefore continue to hold off issuing any flood watches at
this time.
Carney
.LONG TERM... (Monday through Next Saturday)
Issued at 247 PM CST Sat Mar 5 2022
Briefly, for the period beyond Sunday night:
The latest guidance has been coming in drier and drier for Monday in
the wake of the cold front. While a good chance for rain (possibly
mixed with some snow in northern portions of the forecast area)
continues for Monday morning, the amounts are far lighter than in
previous runs, and Monday afternoon is mostly dry now with perhaps a
few sprinkles lingering across southeast Missouri and southern
Illinois. A relatively cold high pressure system builds across the
Midwest Monday night into Tuesday and temperatures will remain near,
to slightly below normal. A brief warm up is expected Wednesday and
Thursday, but another cold front pushes southeast through the
Midwest late Thursday, and Friday and Saturday will be back below
normal. There may be some precipitation associated with the front
Thursday and Friday, but current deterministic guidance does not
look particularly threatening.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 550 PM CST Sat Mar 5 2022
Pre frontal trough is currently moving through the forecast area
with isolated showers. Otherwise, majority of the CAMs are
indicating that a line of strong storms will continue to develop
just ahead of main cold front moving into northeast and central
Missouri between 02z and 04z Sunday, then into St. Louis metro
area after 06z Sunday. With loss of daytime heating and
instability, coverage will be widely scattered in nature so just
have vicinity thunderstorm mention in TAFs. As for winds, they
will remain gusty from the south veering to the southwest then
west to northwest behind the cold front. Winds will diminish by
mid morning on Sunday.
Byrd
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
630 PM EST Sat Mar 5 2022
.SHORT TERM...(This evening through Sunday)
Issued at 424 PM EST SAT MAR 5 2022
Main forecast challenge early this evening will be timing the lull
in precipitation. Current radar trends have the bulk of the
precipication concentrated over the eastern half of the UP/northeast
WI. And, with a persistent warm nose at 850 mb and surface
temperatures generally at or just above the freezing mark, Ptype has
generally been in the form of rain and freezing rain. Local ice
reports so far today have been minimal and in the 0.20 to 0.40 inch
range with short term deterministic models trending toward the Sat
20Z to Sun 00Z time frame for the break between waves. An uptick in
reflectivity per the HRRR is progged to occur across the southeast
again though after Sun 00Z with the bulk of the precip re-entering
the western counties after Sun 02Z.
Temperatures across the east/southeast portions of the forecast area
should be warm enough to keep Ptype as rain, so the winter weather
advisory will be allowed to expire at Sat 22Z. The ice warning, on
the other hand, will remain in place through the night to account
for the second wave. Best chances for some quick ice accumulation
with this wave will come in the Sun 03-06Z time frame with stronger
forcing as the low passes over the forecast area.
Bufkit forecast soundings indicate an influx of colder air tonight,
so could start to see some snow mixing in from west to east before
daybreak Sunday. This will continue into the day Sunday, resulting
in some light 1 to 3 inch accumulations across the Keweenaw and NW
wind snow belts. As the trailing upper low exits the area on Sunday
afternoon though, any lingering large scale ascent will taper off.
.LONG TERM...(Sunday night through Saturday)
Issued at 424 PM EST SAT MAR 5 2022
Near normal temperatures are expected through the first half of next
week with below normal temperatures expected for the second half.
Generally below normal precip is expected next week, but there`s
still a chance for a substantial late week storm system.
The ongoing winter storm pulls away on Sunday with mainly only
flurries ongoing at 00Z Monday. There is some uncertainty about the
state of lake ice Sunday night after more than a day of gusty winds.
If the lake remains mostly ice covered then chances of measurable
precip should remain low on Monday. If lake ice cover is
substantially reduced by Monday then cold air advection and
convergent flow may be adequate for less than an inch of snow
accumulation in the most favored NNW upslope locations. A secondary
area of snow chances near the Lake MI shoreline where chance PoPs
seems justified on Monday as the synoptic system passes to our
south.
A deepening surface low tracks across Northern Ontario toward James
Bay on Tuesday resulting in warm air advection across our CWA.
Overall, precipitation chances are low with this system and
should be primarily focused along the cold front(s) and within the
cold air advection regime. There are some hints of two distinct
cold fronts, with westerly winds behind the first then more
northwesterly winds behind the potential secondary front. Either
way, the post-frontal environment should only be supportive of
light LES.
Potential remains for another impactful winter storm to track
through the region late next week. A polar jet streak dives
southeast across the Pac NW on Wednesday with cyclogenesis near the
southern CO/KS border Wednesday night. The surface low tracks
northeast into the Great Lakes region by Thursday night. By Friday
morning, rapid cyclogenesis is possible beneath a potentially
coupled jet structure as an arctic air mass interacts with a
subtropical moisture plume. A fresh arctic air mass moves in
behind this system with lake effect snow showers likely downwind
of any ice free areas.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 629 PM EST SAT MAR 5 2022
Low pressure lifting through the region today will continue the mess
of ptypes across the area in this TAF period. Overall, LIFR
conditions are expected, with improvement to IFR during the day
Sunday.
The next wave of precip is currently approaching the MI/WI
stateline and will overspread the area soon after 0Z. Expecting
mainly freezing rain at the terminals, but at KSAW temps aren`t
expected to budge much away from 32F, so some rain can`t be ruled
out. As the low moves into the UP, precipitation within the
deformation axis along the lows west and northwest edges will
transtion over to snow and bring light to moderate shower activity
to KCMX and KIWD through the early morning hours. Some snow will be
possible at KSAW as well, but soundings suggest a mix of freezing
rain and snow to be most likely to occur. Lingering low level
moisture from today`s precip and what`s been added to the snow pack
will create areas of mist and freezing fog through the night.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 433 PM EST SAT MAR 5 2022
As a Colorado low approaches the lake tonight, expect easterly winds
to back northeasterly behind the systems cold front. Northeasterly
winds gradually back to northwesterly by midday Sunday as the low
departs. A few low end gales are possible across eastern Lake
Superior Sunday morning and early afternoon as winds back to the
northwest. Winds are expected to drop below 20 kts by Sunday night
as the low quickly leaves.
Southwest winds of 20 to 25 kts return to the lake late Tuesday and
Tuesday night, then become westerly by Wednesday morning due to the
passage of a cold front. Winds of 20 kts are less are expected to
prevail through Thursday night. Northwest winds may increase to 25
kts next Friday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Ice Storm Warning until 7 AM EST /6 AM CST/ Sunday for
MIZ001>005-009-010-084.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TDUD
LONG TERM...EK
AVIATION...JTP
MARINE...EK
Area Forecast Discussion
National Weather Service Paducah KY
850 PM CST Sat Mar 5 2022
.UPDATE...
Issued at 848 PM| CST Sat Mar 5 2022
Important addition to dayshift package to add Flash Flood Watch
for part of the southern Purchase and Pennyrile counties of west
Kentucky from 6 am CST through 9 pm CST Sunday. The vast majority
of the flooding concern will be wholly in aforementioned area in
west Kentucky during that time period and will have far lesser
impact in the short term as one moves closer to the KY/TN border.
This Flash Flood Watch covers the first wave of convection
expected on Sunday. Several of the Convection Allowing Models
(HRRR, NAMNest, Hi-Resolution ARW) have been consistent for
several model runs of pinpoint part of the southeast Purchase and
southern Pennyrile region of west Kentucky for excessive rainfall.
The HRRR and Hi-Res ARW have also verified very well the last
12-24 hours with mass/thermal fields over this area, yielding
higher than normal confidence in the potential for isolated
flooding of low-lying/flood prone areas. Looking at the larger
domain the European Extreme Forecast Index, there is strong
statistical correlation for higher than normal rainfall over this
area ending at 00z Monday with above normal integrated water vapor
and precipitable water values. Although a little more
conservative, the NBM is showing significant precipitation amount changes
over 3-6 hour period at a few locations in the watch area on
Sunday.
MRMS Crest and NASA/NASA Sport soil moisture fields suggesting
that sub-surface soil moisture is still 50-70 percent, despite the
recent days of dry weather across the region. Given the expected
increase of rainfall rates during the morning over the southeast
Purchase area and during the midday and afternoon over the
southern Pennyrile region of west Kentucky, flooding is definitely
a good possibility.
Although the areal coverage of the heaviest rainfall may vary from
north to south due to mesoscale influences, initial concern for
flooding potential with this watch stretches from Lowes, Wingo
and Murray to the west onward to Bremen, Greenville and Elkton
Kentucky to the east. A broad area of 1-3 inches in a short time
is a good bet in this area, especially during the day on Sunday.
Coordinated and collaborated with adjacent NWS offices regarding
this Flash Flood Watch and anticipate most of the flooding
concerns will be wholly within the WFO PAH forecast area. The
prior WFO PAH forecast shift also expressed concern for flooding
and continued the Hydrological Outlook to include this area.
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 251 PM CST Sat Mar 5 2022
Unsettled weather returns to the forecast beginning tonight, with
both hydrological and severe convection issues possible through
Monday morning. PoPs will ramp up from west to east tonight ahead
of an approaching surface cold front. A few rumbles of thunder
look likely with this activity, as model soundings depict amble
elevated instability. Concern is growing for a localized flash
flood threat Sunday morning and afternoon across southwest and
southern KY, as the surface boundary stalls in this area. The
potential is there for multiple rounds of training thunderstorms.
The latest WPC QPF has increased to 1-2" here from 12-24z Sunday,
with the newest CAM guidance showing even higher amounts. Given
the relatively mesoscale nature of this modeled high QPF corridor
decided to hold of off a Flood Watch for now until our confidence
in the placement of heaviest rain is higher.
The surface boundary will lift back to the north Sunday afternoon
and evening as a warm front. This will allow a modestly unstable
and sheared environment to advect into the forecast area,
especially across southeast MO, far southern IL, and far west KY.
A strongly forced line of convection will develop and move into
this environment ahead of another approaching surface cold front.
The timing of the best severe weather risk looks quite late on
Sunday night into Monday morning...from roughly 03 to 12z Monday.
Damaging wind gusts and a couple brief QLCS tornadoes will be the
main hazards.
Further north along the warm front, training elevated convection
will develop, with locally heavy rain expected mainly along and
north of the Ohio River. Storm total QPF remains a broad brush of
1.5 to 3.0" across the CWA, but with locally higher amounts
possible. Hydrologic forecast parameters look favorable for
flooding, with PWAT and IVT values at the 95th percentile or
higher via the NAEFS guidance, as well as soil moisture in the
50-60% range over most of the CWA. Widespread minor/nuisance
flooding is a good bet with pockets of flash flooding possible.
Given we`re still 36 hours away from start of the widespread
heaviest rains, decided to reissue the ESF for now and let the
timing/duration decision for a flood watch be handled by the
midnight shift.
.LONG TERM...(Tuesday through Saturday)
Issued at 251 PM CST Sat Mar 5 2022
Targets of opportunity in the long term are mainly with pops Tuesday
night-Wednesday, and then with the late week fropa/associated cold
air/weather.
In the former, all 4 clusters trend dry on QPF. With this and the
12Z GFS going dry, we moved along with our neighbors to eliminate
the small pop on our southeast border counties that is probably just
an averaging drag from the NBM. We think this improves the forecast,
as it tends to be slower making this adjustment in its output.
In the latter, a strong polar vortex drops into the Great Lakes
toward the end of the week, and drives a cold front across the PAH
FA. Lower trop thermodynamic profiles support all liquid as it
begins Thursday night, with marginal temps nearing 32F in our
northwest border counties by 12Z Friday. At this time, the first
wave of moisture departs, so any change-over should be brief and
light, if it occurs at all.
Another wave of moisture hits Friday afternoon. Again, it`s warm
enough for all rain, but as the upper trof then makes passage Friday
evening, the cold air slams in and offers the best chance at change-
over pcpn. It`s a narrow window, however, as the moisture really
drops off as the night wears on. Still, the NBM WSUP Viewer suggests
a dusting is possible Friday night, esp Friday evening, as this
change-over before ending occurs.
&&
.AVIATION...
Issued at 446 PM CST Sat Mar 5 2022
With the exception of KMVN, VFR ceilings will dominate the WFO PAH
TAF sites through at least 10z Sunday ahead of the first line of
convective activity to move across the area tonight.
Given the complex evolution of the first wave of convection and
the second round of convection associated with the movement of the
next system northward through the area, there is some uncertainty
on the timing and coverage of MVFR/IFR ceilings across the area.
With the exception of KPAH, kept most of the sites in MVFR
category ceilings, but dropped KPAH down to IFR ceilings
especially after 23z Sunday.
Visibilities will be tricky as well, given the uncertainty where
training thunderstorms may develop across the WFO PAH TAF sites.
For now, kept with the default six (6) statute mile range for each
site, but anticipate some amendments as the system draws closer to
the area.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...Flood Watch from 6 AM CST Sunday through Sunday evening for
KYZ006-008-009-011>013-016-017-021-022.
&&
$$
UPDATE...Smith
SHORT TERM...DWS
LONG TERM...DH
AVIATION...Smith
Area Forecast Discussion
National Weather Service Shreveport LA
923 PM CST Sat Mar 5 2022
.UPDATE...
Low level warm air advection/moisture advection continues to
infiltrate the Four State Region this evening. Some weak
isentropic processes are even trying to wring out some weak,
elevated showers across portions of the region as we have seen
this earlier across the northwest half our region and now the
south and east. For the update this evening, raised pops to slight
chance variety areawide to cover the weak showers ongoing. HRRR
and latest NAM output suggests this could continue spotty through
the night. Temperatures are running a little warmer than fcst
hourly mins as of 02-03z but will let the min temp forecast ride
tonight.
No other changes are necessary attm...13.
&&
.PREV DISCUSSION... /issued 451 PM CST Sat Mar 5 2022/
AVIATION...
VFR ceilings currently prevailing across all our terminal sites
attm with heights ranging from 5-7kft. We may lose these ceilings
later this evening before MVFR ceilings return in earnest later
tonight and those ceilings should prevail across all terminal
locations trough much of the morning on Sunday. Cannot rule out
the possibility of IFR ceilings at the LFK terminal but that is
the only site where it was included, at least with this 00z
package. Still think we will see low VFR ceilings returning by
late morning, through the afternoon hours on Sunday with VCSH/VCTS
across most locations during the afternoon. Only mentioned VCTS at
the TXK/TYR and GGG terminals during the afternoon.
Look for SSE to SSW winds overnight with speeds near 10kts. Those
sustained speeds will increase slightly on Sunday with much higher
gusts, mainly across our NE TX terminal locations.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 65 82 54 68 / 20 40 70 70
MLU 65 84 64 74 / 20 20 40 90
DEQ 60 78 41 58 / 30 70 90 30
TXK 64 81 49 61 / 20 50 90 40
ELD 63 82 55 68 / 20 50 70 70
TYR 65 81 48 60 / 20 30 80 30
GGG 64 83 50 62 / 20 30 80 50
LFK 65 83 58 70 / 20 20 60 70
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
13/13
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