SVR-FD 5-17-13

Severe Weather Forecast Discussion for Monday, May 20, 2013
(GFS for 18z and 0z, NAM for 18z only)

Trigger
Cold front over the plains which will move across Missouri Monday/Tuesday.

Winds
    250mb: Nose of jet stream has moved further back into KS but still in W MO by 0z according to GFS. NAM is taking a much more aggressive move as it is putting the nose of the jet stream well into Central MO by 18z. (This change in GFS would suggest that Tuesday may be a better svr day for E MO)
   H5: Big increase in H5 winds along hwy 36 starting at 18z. Speeds up to 70kts along that area. Winds on GFS are out of the SW. NAM is not as predominant as GFS with 45-60kt winds out of the SW.
   850mb: GFS has an existing llj from earlier in the day by 18z but only at 40kts with the nose of the llj south of I-70. Same holds true for NAM. There is winds at 850 North of Hwy 36 but not very impressive. 
   Surface: GFS winds are now showing out of the SSW at 18z. That changes to the South by 0z. NAM agrees with this having SSW surface winds at 5-10kts.
Bulk Shear:
   sfc-850: GFS has once again pulled back on the shear across N MO. Only some 20kt shear around the COU area at 18z. By 0z this kicks up from a line around P Hill MO over to COU then a break and another spot to the NE of UIN. Only 35kts. NAM has now shear thru this level.
   Sfc-700: Once again the bulk of shear has decreased and moved south, now along the I-70 area across MO at 18z. By 0z seeing some 50kt shear across UIN. NAME has no shear again thru this level.
   Sfc-500: Finally some good news. VERY good bulk shear from KC over to Macon MO at 18z, 60-70kts. By 0z GFS has much of that activity in IA. What little bulk shear at this level there is on NAM its here and there, nothing real solid.

Moisture
    Surface: Good 70dp from KC to KIRK according to GFS at 18z. (image below) NAM is pulling back on dp around 60°. By 0z the 70 dp expand to cover all Missouri. bottom line, moisture will not be a problem.
   850mb Dp: GFS has came back on its moisture in NW MO to 0-5° at 18z. at 0z looking at +15° south of I-70 with 12-15° from St. Joe to NC MO. NAM agrees with 18z GFS.
   Mixing: Nothing really has changed at the surface, still have good mixing. 16-18 from KC to NC MO at 18z for GFS. Mixing stays the same for 0z except central MO towards UIN sees a little jump. NAM at 18z is the same but backed off a little. 850 mixing is still impressive as well. hwy 36 towards Chillicothe is upwards of 7-10 at 18z with the same at 0z excepting heading up I-35. This is going to be the main item that determines chase location. (image below) NAM isnt as pronounced as GFS.

Instability
   SBCAPE: GFS CAPE at 18z has backed off for NW Mo but still decent at 2000 j/kg from KC to NC MO. By 0z it blows up with 3000 j/kg common across all of MO. Even seeing a spot of 4000 j/kg in the Pike Counties up to UIN. Little different layout for 18z NAM. Increases of CAPE begin on that KC/NC MO line starting at 2000 j/kg with 2500 in the Macon/KIRK area. 
  LI: Surprise surprise, KC to NC MO like is the spike for LI on 18z GFS as it increase rapidly from 0 to -12 in that area. -13 across all of MO at 0z with a spot of -14 right around UIN. NAM is not as aggressive with LI at 18z. -8 along the line previously mentioned, higher values down by Springfield MO.
   SuperComp: Weird 7-10 around STL on 18z GFS with 4-7 along I-70. 0z  GFS has 7-20! from COU to UIN and then towards ILX. Interestingly, only 2-4 in NW MO. 18z NAM is not as aggressive with only 2-4 along Hwy 36.
   3km EHI: Again weird 3-4 in the STL areal on 18z GFS. By 0z the same line holds true as it did for SuperComp on line from COU/UIN/ILX. 6-8 in UIN extending to the NE. 18z NAM is again not being that aggressive as GFS.
   SigiTor: First look at this with NAM... Not impressive, less then 1 across MO. Not a surprise though considering what it was doing with SuperComp and EHI.

Other
   CIN: Thank you GFS, still putting a big "go there" sign on 18z (image below). Line from KC/NC MO still at 0 CIN. NAM at 18z has NO CIN for MO.
   LCL: Little bit in the Chillicothe area but for the most part it follows the same path as CIN. 18z NAM is putting 750-1000 LCL across MO north of 36.
NAM SimRader: showers out of MO by 15z,Storms firing on Lincoln Co at 18z.
Cloud Cover: GOOD NEWS! N MO looking at most 30% cloud cover by 18z.
   
Notes/Target:
  If you take pieces of GFS and pieces of NAM then this still looks like an impressive day across Monday. sfc-500 bulk shear is good, Instability is still there as well. Was a little worried in previous runs or lingering shower activity or cloud cover, looks like that may not be a problem. Target area is along that KC/NC MO line by 18z.

18z GFS Surface Dp

CIN 18z GFS

SVR-FD 5-16-13

Severe Forecast Discussion focusing on Monday, May 20th.
(ETA based)

Trigger
Cold front located over W MO tailing down to central OK with a surface low attached over Kansas.

Winds
250mb: Still seeing a deep trough digging into the central plains thru the weekend. Progression has slowed a little since previous SVRFD now putting the nose of the jet in extreme NW MO at 0z. 50-60kts.
H5: still showing good SW winds at 500mb heading into N MO.45kts avg but a streak of 50 kts thru KC over towards Chillicothe.
850mb: 18z LLJ now shifted a bit more to the east located from COU to KIRK over to KEOK. 40-45kt llj with winds at a 190°. 0z broadens the llj for all of Western Mo and E. IL.
Surface: still seeing good wind flow from the gulf. winds are not as backing as in previous run for W MO but are for E MO.
Bulk Shear: a lot of differences between levels compared to yesterday.
   18z - sfc-925 is now gone. sfc-850 just a little north of hwy 36 along 35 up to the IA boarder.  sfc-700 is the same area just a little stronger. sfc-500 is the most impressive w. 50kt shear in that same area.
    0z - sfc-850 30kt dot over COU. sfc-700 30kts over Pike MO. sfc-500 fingers coming down the river of 30kts, 40-60 kts on the IA/MO boarder.

Moisture
Surface: DP are still hovering around 70-75° thru pretty much all of Northern Missouri. This also works its way down thru KC down to SW KS. Models are probably still overdoing those numbers but expect dp to be in the upper 60's.
805 Td: still seeing some 14-18° dp in the low levels. probably being a little overdone as well but still within severe perimeters. 18° dp are located over St. Joe, KC then down to SW KS at 0z. that is a little concerning considering the cf should be well across Missouri by that time.
Mixing: surface mixing is decent at 18z. around 14-16. by 0z that amplifies over NE MO and WC IL. 850 mixing still pretty decent across W MO at 18z by 0z the bulk of mixing moves to central MO up to the IA boarder.

Instability
SBCAPE: {5000j/kq across Pike-STL on sunday at 0z.} CAPE still looks good for Monday. 3000 j/kg at 18z down towards Springfield, MO up thru Warrenton, close to I-35 the over to KIRK and UIN. By 0z 3000 j/kg is covering all of the MO/IA boarder with a finger heading thru St Joe and KC and another finger heading thru COU.
LI: follow the same lines as CAPE does for 18z and 0z. -11 to -12 for all of N MO for 18z. By 0z still seeing the same numbers with a -13 north of KIRK.
SuperComp: 4-7 boxed in from west of I-35 and then North of hwy 36 extended past UIN. By 0z the highest numbers are past UIN?!?! Still 2-4 across Northern MO.
EHI: 3-4 at 18z from KIRK to UIN then by 0z 3 along the river up to 8 East of Pike IL.

Other
CIN: not as clear cut on the 18z run as to where the firing line will be as now those locations are seeing -100 CIN. lowest values are on a line from Springfield MO to Marshall. Extreme N MO has no CIN at 18z. By 0z it becomes much more evident where the line will be. No CIN from KIRK down to Columbia.
LCL: 18z- Extremely low LCL's in the NW corner of MO. COU and points south will have too high of LCL to help storms (above 1250). 0z LCL's are in good shape across all of MO.

Notes/Target:
~Not as clear cut today after the model run as it was yesterday. Location of CF is a bit harder then yesterday as it was BOOM there it is then. CF could be slowing down.  Still believe storms will fire up along a line just East of KC with max potential of tornadic activity North of hwy 36. It will probably change but being on 36 seems like the best bet for Monday, maybe close to Chillicothe by 2pm and then work East as the day goes on. Overall still looks like the potential is there, not as excited today as I was yesterday though.

~Do need to keep in mind that overnight convection from Sunday night may be an issue for Monday.
~Luckily will be getting help from NAM models in the next day or so. Might clear up some timing issues.


SBCAPE at 18z

Sfc-500 Bulk Shear

SPC D4-8 Outlook (Day 4 - Sunday, Day 5 - Monday)

SVR-FD 05-15-13

Forecast for next seven days, specifically 5/19, 5/20

Sunday 5/19 (GFS)

Trigger/Target
Cold front extending from MN thru TX with a surface low attached over OK. Focus area Central/Eastern Kansas.

Winds
250mb -  jet nosed over Central Kansas. This has slowed since model run 24 hours ago.
H5 - 60 kt southerly flow over E KS, (unidirectional?)
850mb - llj lost a little intensity over E KS. llj max as 45kts.
~ 850 and 500 are unidirectional (straight line wind event?)
Surface - south winds still giving way to unidirectional winds with 850 and 500

Moisture
60-65° surface dewpoints.

(going to stop there. Not chasing on Sunday and not in forecast area)


Monday 5/20 (GFS)

Trigger/Target
Cold front now over NW Missouri at 18z then move across state by 0z.

Winds
250mb jet streak nose right into NW missouri by 18z/.
500mb winds ejecting right into the same area. 65kts out of the sw. strengthens up to 75kts at 0z
850mb - 50kt LLJ over Western MO. winds out of the south
surface - winds backing from the se 5-10kts,
Bulk Shear - impressive bulk shear from surface up to H7 atleast 45kts. 



Moisture
65+ surface dp over NW/NC Mo. Models have been overdoing them a little but expect them to be in the 60's.

~nice 14° dp in the 850mb area over same area.
~nice mixing up to 850mb from just west of KIRK down to SE KS.

Instability
~Crazy SBCAPE across Missouri during the time period. 18z CAPE above 3000 j/kg over Northern Missouri. It increases by 0z to 5000 j/kg over Eastern MO. Pretty much a certainty these numbers are being overdone do to high temp/dp across the area but still impressive.
~LI - -9 to -10 across Northern MO.
~SuperComp - seeing 4-6 by 18z from NC MO to STL area. Bumps up to 10-15 from E KS to OKC by 0z. This would suggest that the cold front may still be in NW MO by 0z.
~EHI - highest EHI values as of 18z will be in extreme NW MO into NE. By 0z EHI is strongest over NE MO/WC IL. Seeing the same EHI values across E KS to OKC like the SuperComp.

Other Notes:
The bulk shear really caught my attention. If this would be tomorrow I would be targeting the Chillicothe, MO area. Everything we need for tornadic activity is there. SPC already has noticed this system on D6.


Images for Monday:
CINH 0z

LCL 18z