WeatherMonger

About 7 hours late but sun shining here in KSPI

Newest watch, has 50/20 probabilities

No High Risk

69/67 KSPI

No MD for upgrade to High Risk, will they pull the trigger at 20Z?

DVN and ILX 18Z soundings

T'storm watch for IN/OH/W PA

ILX midday update, imagine there will be a few 18Z or off hour RAOB launches as well.

Quote

UPDATE...
Issued at 1134 AM CDT Sat Mar 28 2020

A disturbance propagating out of northern MO into west central IL
has set off a few clusters of storms late this morning. A
disorganized frontal zone is somewhat stalled roughly just south
of I-74. The strongest storm feeding off a region of over 1000
J/KG MLCAPE have been able to produce hail over 1 inch diameter
just southeast of Springfield. This disturbance should move
steadily eastward reaching the IN state line by 1 p.m. Overturning
associated with this convection could diminish the afternoon
development of stronger instability to some degree, however there
should still be plenty of heating potential this afternoon. Given
strong lift and shear associated with the deepening low moving
into IA and the upper Midwest today, and organized by the trailing
cold front, severe thunderstorm potential continues today, and all
of central/southeast IL remains in a moderate or enhanced risk
according to SPC. Large hail and tornadoes are the primary
threats, while locally damaging downburst winds are also a threat.
Consensus of CAMS models indicate this last line of storms should
form in western IL mid afternoon, 3-5 p.m. or so, and progress
eastward through the evening hours. Updates this morning center
around trends in PoPs/thunder chances, mainly due to the late
morning convective clusters.

Looks like only change was extending the enhanced risk a bit SE in MO

Northern MO, SE IA, Western IL clearing out big time.

Went warned to my south

Just started raining here, based on radar could have 3 back to back bouts of heavier rains. Going to take a lot for the atmosphere to recover I would think. Finally heard my first rumble of thunder about 2am as the obernight complex moved through.

No High Risk yet

Quote

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0749 AM CDT Sat Mar 28 2020

   Valid 281300Z - 291200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   EASTERN IOWA AND CENTRAL/NORTHERN ILLINOIS...

   ...SUMMARY...
   A severe-weather outbreak is expected for portions of the Midwest
   this afternoon and evening.  A few long-tracked, significant
   tornadoes are possible, along with large, damaging hail and severe
   gusts.

   ...Synopsis...
   A progressive mid/upper-level pattern will remain in place over the
   CONUS through the period, featuring a strong synoptic trough now
   extending from a 500-mb cyclone over the central High Plains
   south-southwestward over eastern NM to Chihuahua.  The cyclone aloft
   will strengthen and move northeastward to western IA by 00Z, with
   trough southwestward over west TX.  For the remainder of the period,
   the cyclone will become vertically stacked with its low-level
   circulation, moving northeastward to southern WI by 12Z tomorrow.

   At the surface, 11Z analysis showed the main surface low near HUT,
   with Pacific cold front arching across central OK, western
   north-central TX, the Edwards Plateau, and northern Coahuila.  The
   Pacific cold front superficially will exhibit some dryline
   characteristics, but with definitive baroclinicity, as it sweeps
   across the lower Missouri and mid Mississippi Valleys today into
   this evening.  By 00Z, the front should reach extreme eastern IA,
   western IL, eastern/southeastern MO, central AR, northern LA, and
   southeast TX.  By 12Z, the front should reach western OH, middle TN
   and near the central part of the LA coastline.  The warm front will
   move northward across eastern IA, northern parts of IL/IN/OH,  and
   parts of western PA by 00Z.  Further northeastward advance of this
   boundary over PA likely will be prevented until day 2, but by 12Z,
   it should reach the shore of Lake Erie in OH.

   ...Mid Mississippi Valley and vicinity...
   Scattered thunderstorms are expected to form in episodic arcs from
   midday through this evening across parts of central/eastern IA,
   eastern MO, IL, and IN, moving northward to northeastward generally
   at 45-60 kt.  This will include supercells with tornadoes (some
   long-tracked and significant at EF2+ damage levels), large and
   sometimes very large hail, and occasionally severe non-tornadic
   gusts.  Given the fast storm motions, any tornadoes that do form may
   persist for nearly as many miles as minutes of time -- at least,
   until supercells cross more than a short distance into what should
   be a very sharp warm-frontal zone.  

   Intense deep-layer winds and low-level shear will be present, with 
   60-80 kt effective-shear magnitudes, amidst 90-100 kt of 500 mb
   flow, under and near a 150-kt 250-mb jet.  Long, somewhat curved
   hodographs are forecast, yielding warm-sector effective SRH of
   200-400 J/kg, but higher along the immediate warm front where
   storm-residence time will be brief.  A zone of favorable
   destabilization -- narrowing with northwestward extent from IL and
   eastern MO into central IA -- is forecast following morning
   clouds/precip, as diurnal heating and steep midlevel lapse rates
   overspread a plume of moist/warm advection just ahead of the Pacific
   front.  Additional supercells may form in the warm sector over IL
   and move into IN, also offering potential for significant
   tornadoes/hail and damaging wind before this part of the event wind
   down in the evening.

   Given that some uncertainties remain regarding the duration and
   width of destabilization across this region with respect to forecast
   rapid supercell motion across the warm sector, and regarding
   coverage of supercells, we are holding the probabilities to those
   supporting a categorical "moderate" threat at this time.  This does
   not preclude the potential for a tightly targeted area of higher
   probabilities during the day if mesoscale developments warrant.

   ...Central/east TX/Arklatex to Mid South/TN Valley...
   See SPC mesoscale discussion 246 for near-term coverage of a
   marginal severe threat with ongoing convection across portions of
   central/north-central TX, near the Pacific front.  

   Peripheral severe-outlook areas have been expanded southwestward
   into most of east TX to account for the increasing potential of
   development through afternoon along/ahead of the Pacific front, as
   well as more of southern MO and eastern OK on conditional potential
   for ongoing convection now in parts of central OK to produce
   isolated strong-severe hail and gusts into those regions in the next
   few hours.  This area will be characterized by weaker deep-layer
   wind fields and midlevel lapse rates than farther north up the
   Mississippi Valley, but still sufficient in a setting of rich
   low-level theta-e, with enough deep shear to support severe
   potential.  With mean-wind and deep-shear vectors oriented with a
   substantial component parallel to the axis of low-level convective
   forcing, mode should be messy, with a mixture of quasi-linear,
   multicell and supercell characteristics.  Tornadoes will be possible
   from supercells and QLCS-embedded vortices, particularly across
   parts of the Mid-South in closer proximity to the intense mid/upper
   winds.

   ..Edwards/Mosier.. 03/28/2020

URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 66
   NWS Storm Prediction Center Norman OK
   1015 PM CDT Fri Mar 27 2020

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     West-central Illinois
     East-central Missouri

   * Effective this Friday night and Saturday morning from 1015 PM
     until 400 AM CDT.

   * Primary threats include...
     Scattered large hail and isolated very large hail events to 2.5
       inches in diameter possible
     Isolated damaging wind gusts to 60 mph possible

   SUMMARY...Initially elevated supercell across central Missouri
   should progress near the I-70 corridor with additional development
   possible to the east-northeast into the early morning. Large hail
   will be the primary hazard.

   The severe thunderstorm watch area is approximately along and 45
   statute miles north and south of a line from 15 miles west southwest
   of Columbia MO to 30 miles south of Decatur IL. For a complete
   depiction of the watch see the associated watch outline update
   (WOUS64 KWNS WOU6).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Severe Thunderstorm Watch means conditions are
   favorable for severe thunderstorms in and close to the watch area.
   Persons in these areas should be on the lookout for threatening
   weather conditions and listen for later statements and possible
   warnings. Severe thunderstorms can and occasionally do produce
   tornadoes.

   &&

   AVIATION...A few severe thunderstorms with hail surface and aloft to
   2.5 inches. Extreme turbulence and surface wind gusts to 50 knots. A
   few cumulonimbi with maximum tops to 500. Mean storm motion vector
   25050.

   ...Grams

Under a watch here, no watchbox by SPC available

ILX wanted no part of discussing it, here's DVN disco

Quote

Saturday morning...The MO warm front starts to retreat northward
possibly into the southern CWA by late morning, but still hindered
in progression by east-northeast 10-20 MPH post frontal LLVl flow.
As the sfc low deepens toward 990 MB and rolls to near Omaha by
noon, see a scenario where we still have to deal with sctrd
elevated storms north of the warm front for much of Sat morning,
and a lingering chance for hail and localized heavy downpours.
Then the attention turns to...

Saturday afternoon...Closed upper low deepening close to 540 dam over
northwest IA by evening, but models still don`t suggest it to
negatively tilt. Still a dynamic synoptic scale scenario as 150 KT
upper jet rounds the bend and "exit region noses" right acrs the DVN
CWA by late afternoon. Much will depend on the northward extent the
warm front makes it to allow portion of warm moist sector with low
to mid 60 sfc DPTs to skirt acrs the southeast half or more of the
fcst area(how far northwest will it make it?), and timing of
southwest LLVL flow surge from approaching dry slot with dry-line
like effects on it`s advancing edge, to fuel a developing line of
broken generally north to south oriented storm cells/supercells
somewhere acrs the CWA. How far east this occurs, how far north the
warm front makes it, all questions and lingering uncertainty. Deep
mainly southwest speed shear profiles of 70-90+ KTs are troubling,
but back LLVLs for tornadic or funnel development to the sfc may not
be there except when encountering the warm front or other
discontinuity boundaries. With such strong flow profiles,the storms
will be very fast moving over 50 KTs and thus short residence
windows when encountering boundaries. This may make for more short-
lived tornadoes, as opposed to long trackers.

If there are too many cells in a broken line, see the scenario where
community outflow boundaries merge and act as inflow interrupters,
decreasing more lengthy severe threats. But more discrete and
separated cells will still be trouble, it not for a tornado still
able to produce damaging wind gusts and large hail with rear dry
slot interaction. One other question, looking at fcst vertical
profiles and soundings there appears some lack of more robust CAPE
and depth to fuel such high shear profiles. Have scene another
similar scenario several years ago in a high risk window where the
shear was too much/not enough deep CAPE and tore storms apart before
they could better organize. Many questions and uncertainty ongoing,
but still have to respect the rare Moderate risk in portions of our
area tomorrow. Trusted old fashion 12z run MCS tool with it`s
tornadic shear profile is targeting SPC`s Moderate bullseye really
well, but wonder if a bit more southeast adjustment may be warranted
in later updates.

High temps well up in the 60s to mid 70s possible in heart of the
afternoon dry slot-warm sector, and as for rainfall, the afternoon
cells will look to be scattered and very fast moving limiting
dumping too much rain in a spot for a period of time despite ongoing
high PWATs of 1 to 1.4 inches. The heavier rain threat may be in the
north half of the CWA Sat morning with storm clusters still north of
the retreating(or trying to retreat) warm front. Over all, tonight
and Sat 24 hour rainfall amounts now look to be lower, with
widespread 0.50 to 1 inch amounts by 00z Sunday, some areas less.
But the high PWATs also support a few localized swaths of 1-2 inches
acrs areas that can get in on repeat thunderstorm clusters, such as
along a temporary stalled warm front scenario late tonight into Sat
morning.

Behind passing storms, southwest dry slot winds may gust close to
advisory level late afternoon into early evening.


.LONG TERM...(Saturday Night through next Friday)
ISSUED AT 330 PM CDT Fri Mar 27 2020

Key Messages:

1. Severe thunderstorms should be ending across the area at the
beginning of the period.

2. Wind gusts to 50 mph could be possible Saturday night into
Sunday.

3. There are additional chances for precip late in the period.

Discussion:

Ongoing severe thunderstorms are likely at the beginning of the
period.  Most of these storms will likely be in the eastern CWA and
exiting.  Supercells are expected with all potential threats of
severe weather.

On the backside of this system, strong advection of pressure
gradient will lead to winds sustained 25 to 35 mph with gusts as
high as 50 mph.  Expect this to peak sometime in the morning before
waning off by the afternoon.  We will likely need a wind advisory
for these winds.

After this period, expect temperatures in the 40s with rather quiet
weather.  Into next week, model momentum fields vary much and thus
lead to low confidence in possible systems.  As such, we have a
period of extended pops in the long term forecast.  As we get closer
to the event, expect the actual window for pops to get smaller.

&&

Expanded the 10 and 15% hatching SW

Old

New

Reed Timmer put out this outlook map on FB

In a slight risk for tonight now, just inside the northern fringe as they elongated it eastward.

1 hour ago, snowlover2 said:

Very rare update to the current day 3.

 

Beat me to it, just got home and seen that. I know better than to get my hopes up, but 3 straight days in a Mrgl or Slight. Still haven't heard thunder this year.

Have a solid coating- 1/2" here in KSPI

Pavement's actually coated

Snowing here

CPC still with a rather large severe area in the 8+ day range. SPC and WPC have nothing delineated in the 7-8 day range, SPC with predictability too low.

New thing for CPC? Usually the delineate the SPC and WPC areas of notez but now they are going out on their own beyond warmer/colder than average.

Marginal risk for Thursdayfor a portion of the forum, CPC also has a pretty big area delineated just south of the region. Not yet in SPC range

No thunder today, onto the next one.......

Can't let winter ending kill the pessimism