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Severe Weather Threat May 7th - 13th


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Im excited about weds looking at the 18z GFS...one of those days where were already up to 3500 j/kg of SBCAPE by 18z with all of northern IL completely in the warm sector and bump that up to 5000 j/kg by late afternoon with better mid-level flow approaching the area during that time with dew points in the low 70's.

Still days away but just the fact that it looks like its going to be very humid and unstable excites me. Now we just need a subtle s/w to ripple on through to set off something fun.

I'd like this if the flow were 10-15 knots stronger throughout the column.

post-14-0-76414200-1304640605.gif

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This is actually for Saturday the 7th, but some interesting looking soundings for far western/northwest Illinois late Saturday afternoon. The new NAM shows a narrow ribbon of around 1000 j/kg cape in a highly sheared environment. Moisture won't be especially impressive, nor deep though. The NAM does show a nice little 50+kt punch ripping into this area as well. Could make for some mildly interesting storms if we can get the instability up that high.

NAM_218_2011050600_F48_41.5000N_90.0000W.png

NAM_218_2011050600_F48_41.5000N_90.0000W_HODO_SM.png

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Ya the 12z NAM was doing the same thing with regards to saturday, I will actually be at the cubs game for my 21st bday..:pepsi: so praying for no rain.

It looks like on this run of the NAM that a weak but compact almost meso-low like moves from north central IA to near DBQ during the afternoon and has a nice narrow axis of around 1250 j/kg of SBCAPE and the theta-e/dew point axis going up to and behind the low, like a cold-core event. And this setup does have some pretty cold air aloft with it (-18 at H5) so sfc heating would go along way.

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Ya the 12z NAM was doing the same thing with regards to saturday, I will actually be at the cubs game for my 21st bday..:pepsi: so praying for no rain.

It looks like on this run of the NAM that a weak but compact almost meso-low like moves from north central IA to near DBQ during the afternoon and has a nice narrow axis of around 1250 j/kg of SBCAPE and the theta-e/dew point axis going up to and behind the low, like a cold-core event. And this setup does have some pretty cold air aloft with it (-18 at H5) so sfc heating would go along way.

The 00z GFS and RGEM are way different. Actually the RGEM is somewhat similar, just much quicker. I've noticed the RGEM seems about 6hrs too quick sometimes this spring already though. The GFS is much further south of the NAM with the surface low. Pretty big differences for something now less than 48hrs out. If the NAM pans out I'll probably head out just for the hell of it, with it being so close and all.

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Gotta love the dryline setup over the Plains later this weekend and early next week. On Monday the GFS forecast dewpoints in the lower 70s in central Oklahoma, with dews in the lower 20s in the western part of the state lol. Really nice low-level jet feed those two days as well. Wouldn't mind parking myself in Oklahoma City Sunday and Monday. :guitar:

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Gotta love the dryline setup over the Plains later this weekend and early next week. On Monday the GFS forecast dewpoints in the lower 70s in central Oklahoma, with dews in the lower 20s in the western part of the state lol. Really nice low-level jet feed those two days as well. Wouldn't mind parking myself in Oklahoma City Sunday and Monday. :guitar:

This is it--i've seen way too much Kansas and Oklahoma sun. It better produce.

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Gotta love the dryline setup over the Plains later this weekend and early next week. On Monday the GFS forecast dewpoints in the lower 70s in central Oklahoma, with dews in the lower 20s in the western part of the state lol. Really nice low-level jet feed those two days as well. Wouldn't mind parking myself in Oklahoma City Sunday and Monday. :guitar:

Sunday through Wednesday look amazing here, I'm going to have to study my *bleep* off tomorrow and Saturday to free myself up for potential chasing later.

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day 3 -15% probs......hatched over srn ks/ok/tx

...CNTRL PLAINS...

...EXPECT HIGH-BASED STORMS WILL INITIATE OVER THE HIGHER TERRAIN OF WY...THEN

ROOT INTO THE MORE UNSTABLE BOUNDARY LAYER ALONG/NE OF THE SFC LOW

BY LATE AFTERNOON. SUPERCELLS WILL BE POSSIBLE WITH LARGE HAIL AND

POSSIBLY A COUPLE OF TORNADOES. ACTIVITY WILL PROBABLY BECOME MORE

ELEVATED DURING THE EVENING AND SPREAD/DEVELOP EWD INTO CNTRL/ERN

NEB AND POSSIBLY IA/NRN MO OVERNIGHT.

post-556-0-94746200-1304667616.gif

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the new days 4-8 :) , finally something close enough to my area to chase (maybe)

DRYLINE TSTM INITIATION IS COMPARATIVELY MORE UNCERTAIN ON MONDAY

AFTN THAN ON SUNDAY AS MID-LEVELS FURTHER WARM IN ADVANCE OF THE

DIGGING IMPULSE INTO THE DESERT SW. MORE ROBUST SEVERE EVENTS

APPEAR LIKELY ON TUESDAY AND...PARTICULARILY...ON WEDNESDAY /DAY 5

AND 6/ AS THE UPPER STORM SYSTEM BODILY MOVES ONTO THE PLAINS.

THESE STORMS WILL DEVELOP IN INCREASINGLY LARGE HODOGRAPHS AND

BUOYANCY...YIELDING THREATS FOR VERY LARGE HAIL...TORNADOES AND

DAMAGING WIND GUSTS.

post-556-0-37610000-1304672594.gif

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day 3 -15% probs......hatched over srn ks/ok/tx

I think that's a little too far west considering where the NAM/GFS/Euro have the dryline on Sunday Evening.

I like how the NAM is showing a 70kt 250 mb jet nosing into the area on Sunday Evening...could provide the forcing to trigger isolated storms along the dryline in a high CAPE environment.

NAM_250mbWinds_1.png

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The GFS is dry in the Day 3 hatched area, the NAM pops a few storms, but forecast soundings show big temperature-dewpoint spreads and attendant high cloud bases.

The warm front around IA/MO/IL/IN etc. might end up being a better play, but deep layer shear magnitudes continue to look borderline. I think we'll probably see some slight risks for the warm front as we get closer.

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Gosh does eastern NE look sexy on the warm front on monday if the 18z NAM were to verify...looks like some of the of the moisture mixes out some near OAX really wraps up and around along and north of the warm front with easterly flow where the juice is! And also right on the nose of the mid-level jet.

The problem though looks to be the cap, as most of us know without that strong of mid/upper support from the jet. A nice strong but small s/w would go along wa and couldyield some great storms next week if things can work themselves out.

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I like south-central Kansas for Monday. The low level jet looks a little feistier down there. You have 45kts at 800mb near Wichita by early evening. Nice punch at 700mb. Mid and upper support seems better there as well. Capping concerns are definitely there as Thundersnow mentioned. Building heights aren't helping matters much either. If the cap can go in south-central Kansas down to north-central/northwest Oklahoma it will go crazy! Eastern Nebraska and southwest Iowa look interesting if we can get stronger low level wind fields up into that region. Again the damn cap may hold there too.

NAM_221_2011050618_F81_EHI_3000_M.png

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I like south-central Kansas for Monday. The low level jet looks a little feistier down there. You have 45kts at 800mb near Wichita by early evening. Nice punch at 700mb. Mid and upper support seems better there as well. Capping concerns are definitely there as Thundersnow mentioned. Building heights aren't helping matters much either. If the cap can go in south-central Kansas down to north-central/northwest Oklahoma it will go crazy! Eastern Nebraska and southwest Iowa look interesting if we can get stronger low level wind fields up into that region. Again the damn cap may hold there too.

Ya but your going to get some serious heating just behind the dryline with the NAM showing temps into the 100's...still a few days away but I'd rather play further north on the warm front If I could chase, some seriously backed sfc winds and the NAM also showing a secondary LLJ maxima in that area after 0z.

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I continue to be amazed at some of these set-ups over the last 45 days with strong early season capping - I noted in one or two AFD's today that the subject was once again brought up.

I wonder if the strong capping is related to the dry conditions over the Oklahoma and Texas region. It is unusual and has been unusual for awhile now to see some of these capping numbers.

Based on my experience watching severe weather out here for the past 5-6 years, I think it is indeed. And that's what makes this year so frustrating. Any other year, the H5 map progged for Monday would have me salivating. It doesn't look all that dissimilar to the Greensburg case, synoptically. But the hellacious cap will almost certainly rip the setup from our under feet, except possibly along the warm front in NE/IA. I still think that the best bet for significant Plains activity will be from I-70 northward this year, as snowpack in the central and northern Rockies is much better, along with less severe drought in the adjacent central and northern High Plains.

Tuesday and Wednesday still look fairly interesting, yet imperfect due to the trough beginning to roll over and shear out.

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00z NAM still looks interesting in IL on Monday. Parameters aren't extreme by any stretch but there is a pocket of stronger flow and the directional shear is hard to ignore. Unclear if there will be a well organized MCS or more scattered activity but anything that can root at the surface would be something to watch.

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