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Sunday April 10th severe outbreak


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since it's going to to a very active weekend I thought that it may be better to make a sperate thread for Sunday because:

1) it will get confusing to seperate sundays forecast posts from Saturdays current posts

2) with over 600 post arleady Part 2 will likley be started anyway

so to start things off:

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0100 AM CDT SAT APR 09 2011

VALID 101200Z - 111200Z

..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF IA

WI..SE MN

AND NW IL...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER TO

MID-MS VALLEY...GREAT LAKES...OZARKS AND SRN PLAINS...

...TORNADO OUTBREAK POSSIBLE SUNDAY AFTERNOON AND EVENING ACROSS THE

UPPER MS VALLEY...

..UPPER MS VALLEY

AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE INTO THE GREAT PLAINS

SUNDAY AS A POWERFUL 90 TO 110 KT MID-LEVEL JET EJECTS NEWD ACROSS

THE CNTRL STATES. AT THE SFC...A STRONG LOW WILL MOVE NEWD INTO IA

SUNDAY AFTERNOON WITH SFC DEWPOINTS REACHING THE LOWER TO MID 60S F

SOUTH OF A WARM FRONT ACROSS MUCH OF THE UPPER MIDWEST. THE EXIT

REGION OF THE JET WILL OVERSPREAD THE UPPER MS VALLEY SUNDAY

AFTERNOON CREATING STRONG DEEP LAYER SHEAR PROFILES VERY FAVORABLE

FOR SEVERE STORMS. THIS COMBINED WITH STRONG INSTABILITY WILL RESULT

IN A SIGNIFICANT POSSIBILITY FOR SUPERCELLS AND TORNADOES ACROSS THE

MODERATE RISK AREA. AN UPGRADE TO HIGH RISK APPEARS LIKELY ACROSS A

PORTION OF THE UPPER MS VALLEY IN LATER OUTLOOKS.

THE CURRENT THINKING IS THAT CELLS WILL FIRST DEVELOP IN NRN IA AND

SE MN AND MOVE INTO NRN WI DURING THE AFTERNOON AHEAD OF THE TRACK

OF A SFC LOW AND ALONG A WARM FRONT. FORECAST SOUNDINGS AT 21Z NEAR

THE WARM FRONT SHOW MLCAPE VALUES AROUND 2000 J/KG...0-6 KM SHEAR

VALUES NEAR 60 KT AND 0-3 STORM RELATIVE HELICITIES OF 250 TO 350

M2/S2. LOW-LEVEL SHEAR SHOULD INCREASE WITH TIME AS A LOW-LEVEL JET

STRENGTHENS AND APPROACHES FROM THE SOUTH. THIS ENVIRONMENT SHOULD

SUPPORT THE DEVELOPMENT OF TORNADIC SUPERCELLS WITH A POTENTIAL FOR

LONG-TRACK TORNADOES WITH CELLS THAT TRACK ENEWD ALONG THE WARM

FRONT. ADDITIONAL SEVERE STORM DEVELOPMENT SHOULD OCCUR SWD ACROSS

THE WARM SECTOR FROM ERN IA NEWD INTO SRN AND CNTRL WI BY EARLY

EVENING. THIS ACTIVITY SHOULD ALSO RAPIDLY BECOME SUPERCELLULAR WITH

TORNADOES AND LARGE HAIL LIKELY WITH THE MORE DOMINANT CELLS. A

THREAT FOR STRONG TORNADOES SHOULD CONTINUE THROUGH MUCH OF THE

EVENING AS A CLUSTER OF SUPERCELLS MOVES ENEWD ACROSS WI. SEVERE

STORMS SHOULD ALSO DEVELOP SWD INTO NRN AND WRN IL WHERE THE

STRONGER CELLS SHOULD HAVE A TORNADO...WIND DAMAGE AND LARGE THREAT

DURING THE EVENING.

..OZARKS/SRN PLAINS

AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE INTO THE GREAT PLAINS

SUNDAY AS A WELL-DEVELOPED 90 TO 110 KT MID-LEVEL JET EJECTS NEWD

ACROSS THE SRN PLAINS AND OZARKS. THE JET WILL CREATE STRONG DEEP

LAYER SHEAR PROFILES ACROSS MUCH OF THE REGION AS A COLD FRONT

ADVANCES SEWD. THUNDERSTORM DEVELOPMENT SHOULD OCCUR LATE SUNDAY

AFTERNOON FROM NCNTRL MO SWWD ACROSS NW AR INTO ERN OK AND ECNTRL TX

ALONG AN AXIS OF MODERATE INSTABILITY. THE SHEAR ENVIRONMENT SHOULD

SUPPORT SUPERCELL DEVELOPMENT BUT THE FAVORED MODE COULD BE

LINEAR...FORCED BY CONVERGENCE ALONG THE COLD FRONT. STORMS THAT

REMAIN DISCRETE COULD BECOME SUPERCELLS WITH A THREAT FOR ISOLATED

LARGE HAIL. WIND DAMAGE MAY BE THE FAVORED THREAT WITH LINE-SEGMENTS

THAT PERSIST THROUGH THE EVENING WITH THE THREAT GREATEST FROM NW AR

NEWD INTO WCNTRL IL WHERE A 30 PERCENT PROBABILITY IS LOCATED. IF A

SQUALL-LINE DEVELOPS ON THE SERN SIDE OF THE MID-LEVEL JET THEN AN

ENHANCED WIND DAMAGE THREAT COULD EXIST ACROSS ERN AND SRN MO.

..ERN GREAT LAKES AND UPPER OH VALLEY

AN UPPER-LEVEL RIDGE IS FORECAST TO BE LOCATED ACROSS THE SRN

APPALACHIAN MTNS EXTENDING NWD INTO THE UPPER OH VALLEY SUNDAY. AN

AXIS OF MODERATE INSTABILITY IS FORECAST FROM LOWER MI SEWD ACROSS

OH INTO WV. THUNDERSTORM DEVELOPMENT MAY OCCUR BENEATH THE

UPPER-LEVEL RIDGE AS SFC TEMPS WARM DURING THE DAY. HOWEVER...A LACK

OF LARGE-SCALE ASCENT SHOULD KEEP ANY CONVECTION ISOLATED. STRONG

DEEP LAYER SHEAR AND INCREASING LOW-LEVEL FLOW MAY RESULT IN A

MARGINAL WIND DAMAGE THREAT DURING THE AFTERNOON WHEN LOW-LEVEL

LAPSE RATES SHOULD BE STEEP.

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From LaCrosse AFD

ATTENTION THEN TURNS TO ROUND 2...AS MAIN SURFACE LOW PUSHES INTO

MINNESOTA. FORECAST AREA LOOKS TO BE IN THE WARM SECTOR WITH MIXED

LAYER CAPES NEAR 2000 J/KG AND 0-6KM SHEAR VALUES OF 60 KNOTS.

SIGNIFICANT TORNADO PARAMETERS QUITE IMPRESSIVE AND AFTER DISCUSSION

WITH SPC THERE IS A CONCERN FOR THE POSSIBILITY OF LONG TRACK

TORNADOES IN VICINITY OF THE ASSOCIATED WARM FRONT DURING THE LATE

AFTERNOON HOURS AS 0-3KM STORM RELATIVE HELICITY VALUES APPROACH

300 M2/S2. THERE IS SOME QUESTION AS TO THE GENESIS AREA OF

SUPERCELLS IN THE EVENING ALONG THE COLD FRONT...WITH POSSIBLE

DEVELOPMENT OVER THE FORECAST AREA AND THEN SLIDING EASTWARD. NONE

THE LESS THIS COULD BECOME A PARTICULARLY DANGEROUS SITUATION AND

PERSONS SHOULD MONITOR LATER FORECASTS FOR FURTHER DETAILS. HIGHER

END PROBABILITIES PER PREVIOUS FORECASTS STILL LOOK ON TRACK FOR

SUNDAY AFTERNOON AND EVENING.

From Milwaukee

SEVERE THUNDERSTORMS ARE LIKELY TO OCCUR BY LATE AFTERNOON AND

CONTINUE THROUGH THE EVENING HOURS...AS THE COLD FRONT CATCHES UP

TO THE EASTWARD MOVING PRE FRONTAL TROUGH/DRYLINE. STRONG

INSTABILITY WITH MEAN LAYER CAPES OF 1500 TO 2000 J/KG...STRONG

DEEP LAYER 0-6KM SHEAR OF AROUND 70 KNOTS...AND STRONG LOW LEVEL

SHEAR OF AROUND 20 KNOTS...SUPPORT SUPERCELL STORMS WITH POTENTIAL

FOR TORNADOES...VERY LARGE HAIL AND DAMAGING WINDS. SPC DAY 2

MODERATE RISK WITH HATCHED AREA FOR SIGNIFICANT SEVERE LOOKS

GOOD...AND MAY BE UPGRADED TO HIGH RISK IN LATER OUTLOOKS. ALL IN

ALL...A POTENTIAL OUTBREAK OF SEVERE WEATHER IS LIKELY LATE SUNDAY

AFTERNOON AND SUNDAY NIGHT ACROSS THE AREA. STAY TUNED...

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From DVN AFD.

SUNDAY-SUNDAY NIGHT...MAIN CONCERN IS REMAINS NEED TO LOWER POPS BYANOTHER ADDITIONAL 10 PERCENT OR MORE AFTERNOON AND EVENING. LOCALCALCULATIONS SUGGEST SCATTERED TO BROKEN CONVECTION TO FIRE AT 20Z ORLATER AND MOVE NE AT 40-50+ MPH. THIS WITH PW/S OF ~1.25" TO LIMITRAIN AMOUNTS TO LIGHT TO MODERATE WITH NARROW SWATHS NEAR AN INCH INTHE VERY STRONGEST STORMS. HIGH TEMPS SHOULD REACH INTO THE 83 TO 87FRANGE WITH DEWPOINTS OF 61-64F FOR SBCAPE OF 1600-2400 J/KG. INGENERAL...A CONVECTIVE NOT TOO FAR OFF FROM LAST SUNDAY APPEARS INTHE OFFING WITH LARGE HAIL AOA GOLF BALLS REASONABLE WITH SOMEPOTENTIAL TOWARD BASE BALLS. STRONG LOW LEVEL JET WITH S-SW WINDSOF 20 TO 35+ MPH AND A BIT MORE BUOYANCY SUGGESTS A BIT HIGHER RISKOF STRAIGHT LINE WINDS OF 60 TO 70 MPH. ISOLATED TORNADO RISK ISMARGINAL DUE TO LIMITED DIRECTIONAL SHEAR IN SUB CLOUD LAYER. NOEVIDENCE OF A WAVE ATTM THAT WOULD ALLOW FOR BACKING...THIS OBVIOUSLYA CONCERN TO MONITOR AS SYSTEM IS VERY DYNAMIC AND NO DOUBT FURTHERPHASING QUESTIONS MAY LINGER. OVERALL RAIN AMOUNTS OF .25 TO .75AGAIN TO BE ON TAP BUT WITH LARGER AREAS OF LIMITED RAINFALL AGAINDUE TO LOWER COVERAGE.

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From DVN AFD.

SUNDAY-SUNDAY NIGHT...MAIN CONCERN IS REMAINS NEED TO LOWER POPS BYANOTHER ADDITIONAL 10 PERCENT OR MORE AFTERNOON AND EVENING. LOCALCALCULATIONS SUGGEST SCATTERED TO BROKEN CONVECTION TO FIRE AT 20Z ORLATER AND MOVE NE AT 40-50+ MPH. THIS WITH PW/S OF ~1.25" TO LIMITRAIN AMOUNTS TO LIGHT TO MODERATE WITH NARROW SWATHS NEAR AN INCH INTHE VERY STRONGEST STORMS. HIGH TEMPS SHOULD REACH INTO THE 83 TO 87FRANGE WITH DEWPOINTS OF 61-64F FOR SBCAPE OF 1600-2400 J/KG. INGENERAL...A CONVECTIVE NOT TOO FAR OFF FROM LAST SUNDAY APPEARS INTHE OFFING WITH LARGE HAIL AOA GOLF BALLS REASONABLE WITH SOMEPOTENTIAL TOWARD BASE BALLS. STRONG LOW LEVEL JET WITH S-SW WINDSOF 20 TO 35+ MPH AND A BIT MORE BUOYANCY SUGGESTS A BIT HIGHER RISKOF STRAIGHT LINE WINDS OF 60 TO 70 MPH. ISOLATED TORNADO RISK ISMARGINAL DUE TO LIMITED DIRECTIONAL SHEAR IN SUB CLOUD LAYER. NOEVIDENCE OF A WAVE ATTM THAT WOULD ALLOW FOR BACKING...THIS OBVIOUSLYA CONCERN TO MONITOR AS SYSTEM IS VERY DYNAMIC AND NO DOUBT FURTHERPHASING QUESTIONS MAY LINGER. OVERALL RAIN AMOUNTS OF .25 TO .75AGAIN TO BE ON TAP BUT WITH LARGER AREAS OF LIMITED RAINFALL AGAINDUE TO LOWER COVERAGE.

DVN has been very inconsistent with their AFD's for a few days now - the morning AFD's will downplay the threat and then the afternoon ones will come out hyping it up. This has been going on since Wednesday.

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I am glad good rain is coming for us. We need the rain to keep things saturated in the forest to prevent fires. Our snowfall was 50 inches below normal this winter and all of it was lake effect. Lake Effect doesn't contain the water content compared to synoptic snow. We were dry before winter came. Also, the good rain will wash off the tons of road salt on the roads.

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DVN has been very inconsistent with their AFD's for a few days now - the morning AFD's will downplay the threat and then the afternoon ones will come out hyping it up. This has been going on since Wednesday.

Yeah I have seen the same thing with both GRR and DTX over here, Morning talks it up and Afternoon talks it down.

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had to post this...an discussion Gilbert from NIU sent out on our codfcst email list

The new day 2 for Sunday is just scary. SPC is flat out saying that a high risk is likely, and a tornado outbreak is possible (ya think?).

I went with a high risk of severe on a day 3 forecast today. I've never done that before. While this is very "synoptically evident", the mesoscale features cannot be determined at this time, of course. I was going to go with at least a moderate, but bumped to an extraordinary high risk so early because:

1. Synoptically evident

2. Models have been very consistent, and doing well

3. The models were slightly underdoing the moisture and instability (the 0Z runs aren't; they're now up to snuff)

4. All the ingredients are going to be there. Period.

HOW all the ingredients pan out in who gets a tornado and who gets large hail, etc have yet to be seen, but wow. I pray that God would have mercy on southeastern Minnesota, eastern Iowa, much of Wisconsin (with lakes still frozen over as of this afternoon from north of Madison to the UP of Michigan), and northern IL.

I'm not sure what to do yet. Chasing supercells with tornadoes moving at 50-60 MPH in terrain that fairly quickly gets nasty east of Waterloo is not what I call fun. But when you look at that mid-level dry punch coming into DSM from the southwest late Sunday afternoon and pointing at Waterloo, you have to do a double take. We could...and should...see a dryline bulge in eastern Iowa on Sunday. Wrap your brain around that concept for a few moments and see how fast your head spins. These systems usually produce big...and I expect nothing less from this system. Jeff Craven from WFO MKX was noting an analog to a similar system back in 1981 that produced a nasty EF-4 *anticyclonic* tornado in West Bend, WI at midnight, killing 3 people.

Not saying we're going to have EF-4s Sunday night up in Wisconsin at midnight, but I'm just sayin'.

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I am going to be sitting on top of Blue Mounds (400 feet above the surrounding terrain) Sunday. You are able to see 25-30 miles in all directions and it is located west of Mt Horeb and along hwy 18-151. I will be trying out my new i phone with radar scopesmile.gif.

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I am going to be sitting on top of Blue Mounds (400 feet above the surrounding terrain) Sunday. You are able to see 25-30 miles in all directions and it is located west of Mt Horeb and along hwy 18-151. I will be trying out my new i phone with radar scopesmile.gif.

Good luck and stay safe! Sounds exhilarating.

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12 gfs just came in stronger and farther northwest with the LP. looks like it has it pegged at 985mb over st. cloud by 7pm sun. if we can stay in the warm sector and delay the FROPA enough, the cities may be in play, but i'm not convinced that'll be the case.

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Craven's mentioning the 1981 West Bend tornado, eh? Guess I'll have to go down Memory Lane with him.

Bunch of us were out having fun the night of April 3-4th, 1981. To be 16 or 17 and have your license and for it to be 70 degrees on an early April night is an irresistible combination. :thumbsup:

We were about 7 miles away from that tornado when it hit. We knew we might get a good storm, but had no idea how close we were to a BIG problem. Probably about 15-20 of us were in a car caravan, waiting to see if this guy's shed was open and if he had beer to share. And as luck would have it, we were up on a high ridge. When we got blasted by (RFD maybe?) we didn't have a clue, except that it was scary. Nobody (even me, the confirmed wx geek of the bunch) knew we had watches and/or warnings out.

We never saw a tornado, and I don't recall there being much lightning. Just knew the west side of everybody's cars were getting pelted with dirt and gravel. It passed in a few minutes, we got out, went in and partied. Then when we got home a while later, a lot of our parents were up, wondering if we knew about the tornado that had hit West Bend. Remember, this was all before cell phones, 24-hour Breaking News!! and the like. It ended up being a very big deal; everyone around here has a story.

Now to contribute something useful to this thread, I'll type up where you can chase in WI, with decent views and road options. If you take the current SREF 50% bullseye verbatim (insert standard disclaimers), there could be a real decent chance of a viewable tube in WI tomorrow aft/eve. Stand by for my slant on where you can chase in WI without pulling your hair out.

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Craven's mentioning the 1981 West Bend tornado, eh? Guess I'll have to go down Memory Lane with him.

Bunch of us were out having fun the night of April 3-4th, 1981. To be 16 or 17 and have your license and for it to be 70 degrees on an early April night is an irresistible combination. :thumbsup:

We were about 7 miles away from that tornado when it hit. We knew we might get a good storm, but had no idea how close we were to a BIG problem. Probably about 15-20 of us were in a car caravan, waiting to see if this guy's shed was open and if he had beer to share. And as luck would have it, we were up on a high ridge. When we got blasted by (RFD maybe?) we didn't have a clue, except that it was scary. Nobody (even me, the confirmed wx geek of the bunch) knew we had watches and/or warnings out.

We never saw a tornado, and I don't recall there being much lightning. Just knew the west side of everybody's cars were getting pelted with dirt and gravel. It passed in a few minutes, we got out, went in and partied. Then when we got home a while later, a lot of our parents were up, wondering if we knew about the tornado that had hit West Bend. Remember, this was all before cell phones, 24-hour Breaking News!! and the like. It ended up being a very big deal; everyone around here has a story.

Now to contribute something useful to this thread, I'll type up where you can chase in WI, with decent views and road options. If you take the current SREF 50% bullseye verbatim (insert standard disclaimers), there could be a real decent chance of a viewable tube in WI tomorrow aft/eve. Stand by for my slant on where you can chase in WI without pulling your hair out.

Based on the SREFs, the area bounded by West Bend, Waukesha, down to the Illinois border, Beloit, Madison, up through maybe Stevens Point and then back south again will be prime territory. I hope most cars are off I94 b/w Madison and Milwaukee by evening (except chasers, of course).

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I laugh when out-of-staters automatically discount chasing in WI. It's like when I say that the state of "Misery" is useless for chasing. A lot of Missouri is bad but it's not 100% hopeless, everywhere. (altho navigators who never got carsick before in their lives and ended up puking on Missouri chases might dispute that, LOL) And sometimes us chasers are just going to go where the storms are best, regardless. We all get that.

But, if you want to have better visibility and road options in WI, I suggest you zero in on the areas east, northeast and north of Madison. I'm sure other folks could chime in here, and I hope they do. All things equal, I'd want to chase in an area of south-central and central WI bounded by: Madison on the SW, over east to a bit west of Waukesha (talking north of I-94.) From Waukesha continuing north up to Fond du Lac and Oshkosh and Appleton, on the west side of Hwy 45 and Lake Winnebago. Then going WNW to about Stevens Point and WI Rapids, basically along and south of Hwy 10. From Wisconsin Rapids, going south, just stay east of the Wisconsin River, and back south toward Madison again. Most places inside that irregular circle are decent chase territory.

The person who spoke about the driftless area -- I liked their strategy of being on top of something like Blue Mounds. Many places in SW WI have awesome vistas. There's merit for simply finding one of those places and hoping like heck one of these ropes hauling azz comes within your view.

One last thing, this is coming from a 46 year-old. I know chasers chase. BTDT. But WI isn't West Texas, Oklahoma or KS. There's more people, more Sunday drivers, more farm equipment and critters, too. Do your best to drive sanely and defensively. Don't be the headline in Monday's news. As a lifelong Badger, I thank you in advance. :thumbsup:

EDIT -- 11:40 central -- I see while I was taking my usual 1000 words pace, wisconsinwx summed it up perfectly. Plus he/she is right that the area south of Madison down to Monroe, Beloit and then south to Rockford, IL is good chase territory.

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You can just feel the anticipation by the lack of posts on this board, waiting for the midday update for the SWODY2.

We are hosting 40+ people for a birthday party tomorrow from 1 - 6 p.m.. House cleaning has been ongoing but we need to kick it in to high gear or be stuck with it all tomorrow morning.

Meanwhile, my wife says I should not dare scare people away early by my "storm talk." I try not to overplay but I think the wording through local media outlets will have already informed many anywayMany will be here from Chicago. Assuming these storms fire to the west, at least they'll be heading away and not into them on the way home.

I'm also hoping I'll be able to get out of town west or northwest before things come in (after 6 of course :rolleyes:), and that it happens before dusk. The good news is both of those directions is largely flat and open from here. A fascinating lead up no doubt for the region. On the heals of the epic lead up to the GHog Blizzard as well.

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We are hosting 40+ people for a birthday party tomorrow from 1 - 6 p.m.. House cleaning has been ongoing but we need to kick it in to high gear or be stuck with it all tomorrow morning.

Meanwhile, my wife says I should not dare scare people away early by my "storm talk." I try not to overplay but I think the wording through local media outlets will have already informed many anywayMany will be here from Chicago. Assuming these storms fire to the west, at least they'll be heading away and not into them on the way home.

I'm also hoping I'll be able to get out of town west or northwest before things come in (after 6 of course :rolleyes:), and that it happens before dusk. The good news is both of those directions is largely flat and open from here. A fascinating lead up no doubt for the region. On the heals of the epic lead up to the GHog Blizzard as well.

Yeah, any major severe weather outbreak we get up here before May or June is rare, and perhaps it will be a sign of what this summer has in store? Anyways, after hearing the GFS shifted about 60 miles northwest at the 12z run, I guess I can't say it's a certainty yet, but it's looking like from Madison to LaCrosse over to Green Bay will be primed.

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SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE

NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD

1629Z SAT APR 09 2011

A GOES-EAST RSO WILL BE IN OPERATION FROM 9/1644Z TO 10/0344Z TO

HELP WITH SVR WX OPS.

$$

SHIREY/SDM/NCO/NCEP

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