March '10 Weather Discussion

[rod4soonrs]

anyone remember snow totals for the season, and what we need to break records?

[venture]

Text from the watch.

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
320 PM CDT THU MAR 18 2010

OKZ004>031-190430-
/O.NEW.KOUN.WS.A.0003.100320T1200Z-100321T1200Z/
HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD-
NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-
BECKHAM-WA****A-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN-
CLEVELAND-POTTAWATOMIE-SEMINOLE-
INCLUDING THE CITIES OF...BUFFALO...ALVA...CHEROKEE...MEDFORD...
PONCA CITY...ARNETT...WOODWARD...FAIRVIEW...ENID...PERRY ...
CHEYENNE...TALOGA...WEATHERFORD...CLINTON...WATONG A...
KINGFISHER...GUTHRIE...STILLWATER...ELK CITY...SAYRE...CORDELL...
ANADARKO...YUKON...EL RENO...MUSTANG...OKLAHOMA CITY...CHANDLER...
CHICKASHA...PURCELL...NORMAN...MOORE...SHAWNEE...S EMINOLE
320 PM CDT THU MAR 18 2010

...WINTER STORM WATCH IN EFFECT FROM SATURDAY MORNING THROUGH
SUNDAY MORNING...

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING FOR HEAVY SNOW
ACROSS PORTIONS OF NORTHERN...WESTERN...AND CENTRAL OKLAHOMA.

* TIMING: EARLY SATURDAY MORNING THROUGH SUNDAY MORNING.

* MAIN IMPACT: HEAVY WET SNOWFALL REDUCING VISIBILITY AND
ACCUMULATING OVER 4 INCHES IN MANY AREAS...WITH LOCAL AMOUNTS
OVER 8 INCHES IN NORTHCENTRAL OKLAHOMA.

* OTHER IMPACTS: WIND GUSTS OVER 45 MPH WILL COMBINE WITH
TEMPERATURES JUST BELOW FREEZING TO PRODUCE WIND CHILLS IN THE
TEENS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW ACCUMULATIONS ALONG WITH STRONG WINDS THAT MAY IMPACT TRAVEL
AND STRESS LIVESTOCK. CONTINUE TO MONITOR THE LATEST FORECASTS.

[venture]

anyone remember snow totals for the season, and what we need to break records?

This is what I can find on NCDC...which includes Snow, Ice Pellets, and Hail.

Feb '10: 1.5"
Jan '10: 5.2"
Dec '09: 14.0"

Total for the period: 20.7"

As far as records...http://downloads.newsok.com/knowit/okcsnowfall.pdf

Looks like we need to break 25.2" for the seasonal record. It should be noted, March is month where we normally see our highest snowfall events.

[rod4soonrs]

Here's Mike's totals

[venture]

OUN's first stab.

[OKCisOK4me]

I like that second graphic a lot better. *Weather forecaster* needs to take a chill pill--seriously...

[PennyQuilts]

Wake me when it's over. Like...July???

[Thunder]

I like the first graphic.

Just a reminder, rod4soonrs posted that graphic being linked to KFOR's site. It will change the next time a new graphic is uploaded.

For weather, save the graphics, upload them to imageshack.us and link to them on here. That way we can see the graphics at the time of the post rather than months later on seeing a Summer graphic in a Winter topic.

[venture]

Evening model runs are in and will have a discussion for each.

GFS
Snow change over in OKC looks to happen around 6-7AM on Saturday. Main bulk of precip is east of I-35 by this time, but some lingering wrap around. Wind will still be insane this weekend, so blowing snow is going to happen regardless of how much we get. It only takes a few inches to get snow drifts. Melting will take place for the first few hours of snowfall, so that will limit amount some.

Precip forecast looks like around 1" in SW OK, 2-3" NW, 3-5" NC, 2-4" Central, and 1-3" SC.

NAM
Snow change over in OKC is similar to GFS at 6-8AM time frame. Similar to GFS bulk of precip has pushed east, with lingering wrap around. Blowing snow and all that jazz.

Precip forecast shows 1" in SW OK, 1-2" NW, 3-6" NC, 1-3" Central, and 1-2" SC.

So my thoughts, the system is slowing and this will probably cause issues with the models getting a handle on this. If colder air gets in sooner, we'll see change over happen with the bulk of precip still here. If cold air doesn't come in fast enough, amounts will be much lighter as bulk of precip will be rain. Are we going to get a major snow storm? It depends on how things play out. If models show consistency on the lower totals, then probably not. Tonight's run definitely indicate just an annoying bout of snow with a good deal of wind. If anything, this will be more of a white out/blowing snow event than an accumulating snow event.

Either way, it's the last gasp of winter before it all melts in a day or two.

[venture]

Area forecast discussion
national weather service norman ok
1013 pm cdt thu mar 18 2010

.update...little emphasis on the overnight gridded forecast at
this time. Most effort is going into ramping up the winter weather
message through various products. The key feature driving the
sudden upswing in snow and wind expectations...was an upper jet
streak that came onshore into the data network over western canada
early thursday. That feature is now into montana/idaho...and
digging toward a date with the late season arctic frontal zone
that will be setting up in the southern plains by saturday
morning. With the jet streak firmly in the data network over north
america...model consensus seems to have developed. The model track
of a closed and deepening cyclone near the red river on
saturday...with climatologically deviate...strong easterly wind
components at 850-700 mb...supports the idea of heavy snow and
strong winds. The only outlier has been the nam...but its 00z run at
least trended toward a stronger system.

The main question now...is how badly the snow will blow to reduce
visibility. Compared to the december storm...temperatures will be
warmer and sun angle higher...making the snow wetter. And winds...
Although very strong...are not forecast to be as severe as they
were during that storm. Still...there will no doubt be significant
impacts to travel. The heaviest snow totals look to occur near the
overlap of two outbursts of snow...affecting north central
oklahoma. The first outburst will occur within the strong frontal
zone saturday morning...while the second will occur as a jet
streak rounds the base of the trough...and the mid level cyclone
undergoes its most rapid deepening near central and north central
oklahoma saturday afternoon. The mature cyclone will translate
only slowly eastward...such that wraparound snow may continue
along i-35 eastward well into sunday morning.

[venture]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1205 AM CDT FRI MAR 19 2010

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
PATTERN SHIFT ALOFT WILL CONTINUE THROUGH PERIOD AS LOW CONTINUES TO
MOVE FARTHER OFF SERN CONUS OVER ATLANTIC. HEIGHTS WILL FALL ACROSS
MUCH OF CENTRAL/SRN ROCKIES AND ADJOINING PLAINS AHEAD OF TWO
PRIMARY SHORTWAVE TROUGHS...
1. INITIALLY OVER SRN NV...AND FCST TO PIVOT SEWD AND EWD ACROSS
NWRN/N-CENTRAL MEX THIS PERIOD.
2. NOW MOVING SSEWD OVER WRN MT...FCST TO CROSS 4-CORNERS REGION
AROUND 20/00Z...DECELERATING AS IT MOVES SEWD OVER REMAINDER NM
DURING ENSUING 12 HOURS.

AT SFC...COLD FRONT IS ANALYZED ATTM FROM SERN CO NEWD ACROSS NWRN
KS AND E-CENTRAL NEB. BY 20/00Z...THIS FRONT SHOULD MOVE SEWD TO
NEAR ORD...COU...BVO...LTS...LBB...ROW...ABQ. BY 20/12Z...FRONT
SHOULD BE INVOF SBN...STL...FSM...DFW...AUS...HDO AND INTO NRN
COAHUILA. FRONTAL-WAVE CYCLONE MAY DEVELOP OVER SERN OK NEAR END OF
PERIOD...AS NM UPPER TROUGH APCHS. DRYLINE...FROM COAHUILA NWD
ACROSS SW TX TO FRONTAL INTERSECTION OVER W-CENTRAL TX...WILL BE
SOMEWHAT DIFFUSE FOR MOST OF PERIOD GIVEN INCOMPLETENESS OF
MOIST-SECTOR AIR MASS MODIFICATION.

...PORTIONS OK...NWRN/W-CENTRAL TX...
BAND OF CONVECTION...INCLUDING WIDELY SCATTERED TO SCATTERED
TSTMS...IS EXPECTED TO FORM INVOF SFC COLD FRONT DURING MID-LATE
AFTERNOON...INCREASING IN COVERAGE INTO AT LEAST EARLY EVENING.
MAIN CONCERN WITH THIS ACTIVITY WILL BE OCCASIONAL HAIL AND GUSTS TO
NEAR SVR LIMITS. LACK OF GREATER PRE-STORM LAPSE RATES
ALOFT...WEAKNESS OF INFLOW-LAYER MOISTURE...AND RESULTING
IMPEDIMENTS TO BUOYANCY...AND MRGL SHEAR PROFILES...COMBINE TO KEEP
SVR POTENTIAL TOO MRGL AND DISORGANIZED FOR CATEGORICAL OUTLOOK
ATTM.

CORRIDOR OF SFC DEW POINTS LOW-MID 50S F -- FRAGMENTED DIURNALLY BY
DIABATIC HEATING/MIXING -- SHOULD RETURN NWD ACROSS N TX AND
PORTIONS OK SE OF COLD FRONT AND E OF DRYLINE. RELATED LOW LEVEL
WAA/MOIST ADVECTION WILL CONTINUE NOCTURNALLY...ALTHOUGH ANTECEDENT
AIR MASS THETAE SHOULD REMAIN SUFFICIENTLY WEAK THAT SIGNIFICANT
INCREASE IN SBCINH WILL OCCUR AHEAD OF FRONT CORRESPONDING TO SFC
DIABATIC COOLING. ACCORDINGLY MODIFIED WRF/ETA-KF SOUNDINGS YIELD
MLCAPE UNDER 750 J/KG OVER NW TX WHERE LAPSE RATES ARE RELATIVELY
MAXIMIZED BUT MOISTURE STILL SPARSE...TO UNDER 500 J/KG OVER CENTRAL
OK WHERE WEAKER LAPSE RATES BUT SLIGHTLY GREATER MOISTURE MAY BE
FOUND. FRONTALLY FORCED CONVECTION -- AIDED BY SFC HEATING --
SHOULD FORM AND SHIFT GENERALLY EWD...WITH SOME SWD BACKBUILDING
TOWARD NRN EDWARDS PLATEAU POSSIBLE.

WITH UPPER TROUGHS STILL LAGGING TO SW AND W OF THIS AREA...ONLY
MODEST HEIGHT-GRADIENT ENHANCEMENT IS EXPECTED...AS WELL AS WEAK
LOW-LEVEL SPEED SHEAR. THIS WILL LIMIT BOTH HODOGRAPH SIZE AND
DEEP-LAYER BULK SHEAR -- E.G. 25-35 KT EFFECTIVE SHEAR ALONG/AHEAD
OF FRONT DURING LATE AFTERNOON/EARLY EVENING. EXPECT SVR
POTENTIAL...THEREFORE...TO BE RATHER SPORADIC...AND TO DIMINISH
AFTER ABOUT 20/03Z AS BOUNDARY LAYER STABILIZES.
TSTMS...HOWEVER....MAY PERSIST INVOF FRONT FOR MUCH OF THE
NIGHT....ROOTED IN REGIME WHERE CONTINUED FRONTAL FORCING IMPINGES
ON ELEVATED WARM-SECTOR LAYER OF INCREASING MOISTURE.

..EDWARDS/STOPPKOTTE.. 03/19/2010

[oknacreous]

The 06 UTC runs of the GFS and NAM both came in with 10-15 inches of snow for OKC Saturday, with the 00 UTC run of the European around 10 inches. Latest run of the SREF (03 UTC) indicates a mean snowfall forecast of about 8 inches but with possibilities ranging from 4 to 14 inches. Big question will be where the comma head and deformation zone set up with this one - on top of I-35 or a little to the east. I'm going with pattern recognition on this one - it's a classic setup for heavy snow in central Oklahoma, and mid-March is the time we get wet snow that piles up quickly. So I'm going with an average of 8-10" in OKC with this one, with locally 12".

[rod4soonrs]

from the NWS:

THIS JUST IN - 06Z NAM HITS MUCH OF CENTRAL/NE OK WITH 15-25
INCHES OF SNOW BEFORE ALL IS SAID AND DONE ON SUNDAY. NOT BUYING
THAT MUCH YET... BUT WE WILL BE LOOKING VERY CLOSELY AT THIS RUN.

[adaniel]

I have to ask, how are these models computing snowfall amounts, as in, are these insane amounts of snow what the models think will fall from the sky or actually accumulate? Every forecast I've seen says it will hover aorund 32 until late Saturday afternoon, and even then it will take a few hours for the ground to get to less than 32 given how warm its been lately.

Also, to add one thing: if these models continue to indicate huge snowfall amounts how long before these winter stom watches are upgraded?

[venture]

I have to ask, how are these models computing snowfall amounts, as in, are these insane amounts of snow what the models think will fall from the sky or actually accumulate? Every forecast I've seen says it will hover aorund 32 until late Saturday afternoon, and even then it will take a few hours for the ground to get to less than 32 given how warm its been lately.

Also, to add one thing: if these models continue to indicate huge snowfall amounts how long before these winter stom watches are upgraded?

Warnings will go out later today. To the first part, I think that is one part that is missing...there needs to be a lot taken into account for this being a very wet snow and also it falling on a wet/warm ground. Of course if the intensity is high enough, it'll offset that...but there is going to be melting/compacting with a wet snow right away.

12Z runs are just now coming in, will wait to see what they say. I typically don't care for the secondary runs (6Z/18Z) as they tend to have some wild swings. However, if 12Z backs them up a bit...then we may need to be concerned a bit.

OUN did lower snow fall totals based on the 0Z runs, which you can see in their graphic a few posts back.

[rod4soonrs]

They did say 3-6 for metro, now 4-8 north side.

[possumfritter]

Last night on Fox25, the weatherman said as much as 12" possible, depending on what track the storm took.

[venture]

12Z NAM is coming in with 6-12" for the Metro now.

[venture]

GFS isn't far off...6-10" for the Metro area.

[oknacreous]

The winter storm warning is being generated and uploaded as I type this, will include OKC metro area.

[venture]

Text of warning.

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
1145 AM CDT FRI MAR 19 2010

...SIGNIFICANT WINTER STORM BEARING DOWN ON THE SOUTHERN PLAINS...

A SIGNIFICANT WINTER STORM IS EXPECTED TO AFFECT OKLAHOMA
BEGINNING IN NORTHWEST OKLAHOMA AS EARLY AS TONIGHT. MUCH COLDER
AIR IS BEGINNING TO MOVE INTO NORTHWESTERN OKLAHOMA... AND WILL
OVERSPREAD THE REST OF OKLAHOMA AND NORTHERN TEXAS LATER TODAY AND
OVERNIGHT. A POWERFUL LATE-WINTER STORM SYSTEM WILL BRING SNOW AND
BLOWING SNOW TO MOST OF NORTHERN... CENTRAL... AND EASTERN
OKLAHOMA... BEGINNING IN NORTHWESTERN OKLAHOMA TONIGHT AND THEN
SPREADING SOUTHEAST TONIGHT AND SATURDAY. HEAVY SNOW... STRONG
WINDS... AND SEVERE BLOWING AND DRIFTING SNOW WILL LEAD TO
BLIZZARD OR NEAR- BLIZZARD CONDITIONS IN PORTIONS OF OKLAHOMA SATURDAY
AND SATURDAY NIGHT. SNOW WILL CONTINUE TO ACCUMULATE INTO SUNDAY.
TRAVEL WILL BECOME VERY DIFFICULT OR IMPOSSIBLE IN SOME AREAS THIS
WEEKEND. THIS IS A POTENTIALLY DANGEROUS WINTER STORM SITUATION
WHICH NEEDS TO BE TAKEN SERIOUSLY. PREPARATIONS FOR SEVERE WINTER
WEATHER SHOULD BE PERFORMED TODAY... AND COMPLETED BY TONIGHT.

OKZ008-012-013-018>020-024>032-042-200045-
/O.UPG.KOUN.WS.A.0003.100320T1200Z-100321T1200Z/
/O.NEW.KOUN.WS.W.0004.100320T0900Z-100322T0000Z/
KAY-GARFIELD-NOBLE-KINGFISHER-LOGAN-PAYNE-CANADIAN-OKLAHOMA-
LINCOLN-GRADY-MCCLAIN-CLEVELAND-POTTAWATOMIE-SEMINOLE-HUGHES-
PONTOTOC-
INCLUDING THE CITIES OF...PONCA CITY...ENID...PERRY...
KINGFISHER...GUTHRIE...STILLWATER...YUKON...EL RENO...MUSTANG...
OKLAHOMA CITY...CHANDLER...CHICKASHA...PURCELL...NORMAN...M OORE...
SHAWNEE...SEMINOLE...HOLDENVILLE...ADA
1145 AM CDT FRI MAR 19 2010

...WINTER STORM WARNING IN EFFECT FROM 4 AM SATURDAY TO 7 PM CDT
SUNDAY...

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WARNING FOR HEAVY SNOW AND NEAR BLIZZARD CONDITIONS...WHICH IS IN
EFFECT FROM 4 AM SATURDAY TO 7 PM CDT SUNDAY. THE WINTER STORM
WATCH IS NO LONGER IN EFFECT.

* TIMING: EARLY SATURDAY MORNING THROUGH SUNDAY MORNING.

* MAIN IMPACT: HEAVY SNOW AND STRONG WINDS GUSTING OVER 40 MPH
CREATING NEAR-BLIZZARD CONDITIONS. SNOWFALL OF 4 TO 8 INCHES IS
LIKELY OVER THE WARNING AREA WITH. LOCAL AMOUNTS OVER 8 INCHES
WILL BE POSSIBLE ACROSS PORTIONS OF CENTRAL AND EAST CENTRAL
OKLAHOMA.

* OTHER IMPACTS: WIND CHILL TEMPERATURES WILL FALL INTO THE
TEENS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED AS WELL AS STRONG WINDS CREATING NEAR-BLIZZARD CONDITIONS.

[mugofbeer]

Sounds like deja vu of Christmas Eve all over again !!

[Thunder]

This is gonna be worse than the Christmas Blizzard. THIS IS IT!!!!!

The governor is preparing to declare STATE OF EMERGENCY!!!

[mugofbeer]

Well if they are that certain about it, just watch, we'll get a dry finger of air out of Mexico and it will all miss us. (smile)

[venture]

This is gonna be worse than the Christmas Blizzard. THIS IS IT!!!!!

The governor is preparing to declare STATE OF EMERGENCY!!!

Okay. Time to unplug your computer and put your tinfoil hat back on. :-P