Plains snowstorm: 18-21 March

[senorpepr]

Okay... for what it's worth... I'm starting to look at the 12Z GFS. I'm scratching my head, yet glad that I don't normally forecast winter events in the US. Anyway... I'm sticking bby my forecast above, but I will say at this time the 12Z GFS is "interesting." If it verifies, I hope you didn't put away your snowblowers yet. I'll look into it further...

[senorpepr]

Just a note...

The most snow during a single storm for Omaha was 18.3" on 11-12 Feb 1965. Omaha's most snow during a single month -- 29.2" during March 1912, which fell in 5 storms.

[Craig]

Okay... for what it's worth... I'm starting to look at the 12Z GFS. I'm scratching my head, yet glad that I don't normally forecast winter events in the US. Anyway... I'm sticking bby my forecast above, but I will say at this time the 12Z GFS is "interesting." If it verifies, I hope you didn't put away your snowblowers yet. I'll look into it further...

Please still be here.....Is there any chanec there wont be any dry air?

[simplykristi]

We will get some rain and a little snow.

Kristi

[Craig]

All my mets are forecasting 10-15 inches of snow here for the omaah area. SNOWDAY! Heaviest snow Sun afternoon-tuesday morn

[lester]

TWC is saying rain/snow mix
(for my area that is)

[Omaha DUDE]

Nobody is saying rain snow mix for Omaha, NE.

[Craig]

all snow for Omaha

[senorpepr]

Nobody is saying rain snow mix for Omaha, NE.

NWS has been hinting at it...

[Omaha DUDE]

They wouldn't be so sure about 12 inches plus already are local mets never would say that this early.

[Omaha DUDE]

Just looked at NWS graphical forecast shows no Mix or Rain just snow. Went to Omaha forecast Snow likely is all it says only mix is from saturday night into sunday morning.

[Craig]

They wouldn't be so sure about 12 inches plus already are local mets never would say that this early.

they seem pretty sure..even this morn. they said even more. totoals 12-18 inches!

[simplykristi]

I just went over to NOAA... NWS has posted a winter weather advisory for Omaha. No way is Omaha getitng a big snowstorm. But then again, who knows?

Kristi

[senorpepr]

Okay... now the numbers are starting to increase...

Although we still have to look out locally... convection to our south and dry air from our east may still pose a problem.

[Omaha DUDE]

I just went over to NOAA... NWS has posted a winter weather advisory for Omaha. No way is Omaha getitng a big snowstorm. But then again, who knows?

Kristi

Well that is only the first part of the storm. We are supposed to get 2-4 inches of snow sat night into sunday morn it takes a break and the 2nd band comes where we are supposed to get an addition 12 inches +.

[wx247]

Pay close attention to the amount of convection to your south. That will be your worst enemy as far as this storm is concerned.

[Craig]

Omaha dude...that is for the first part of the storm..the second part will be MUCH heavier. my guess right now is 12-16 inches

[Omaha DUDE]

I know that is for the first part of the storm (winter weather advisory) i was telling kristi that.

[senorpepr]

Still looks like convection and dry air pose a threat...

Code: Select all

FXUS63 KOAX 182124
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
324 PM CST SAT MAR 18 2006

.DISCUSSION...

SYNOPSIS...12Z SUBJECTIVE UPPR AIR ANLYS INDCD A SHRTWV RIDGE FM
ND SWD INTO SRN TX. UPSTRM SIG SYSTEM WAS MOVING THRU THE GREAT
BASIN WITH AN ASSOCIATED H5 HEIGHT FALL OF 100 M AT KNKX. AN
INITIAL SHRTWV AHEAD OF THE MAIN SYSTEM WAS NOTED OVR AZ/UT AT
12Z. AT H85 RIDGE AXIS HAD SHIFTED SLIGHTLY EWD AND EXTNDD FM
CNTRL MN SWD INTO WRN MO. A WRM FNT HAD DEVELOPED FM WRN KS INTO
ERN OK. 20Z OBJECTIVE MSAS ANLYS INDICATED SFC RIDGE FM ERN MN SWD
INTO ERN MO WITH LO PRES OVR CNTRL WY. REGIONAL RADAR MASAICS
INDCD MOST OF THE LIGHT -RA/SN HAD ENDED ACRS THE REGION.

FORECAST...QUIET EVNG IN STORE FOR MOST OF THE FA. AS NEXT PIECE
OF SHRTWV ENERGY OVR NM/CO THIS AFTN LIFTS NEWD INTO NEB/SD LATER
THIS EVNG...EXPECT UPPR LVL DIVERGENCE TO INCREASE SIGNIFICANTLY
OVR CNTR NEB. THIS ALNG WITH STG WAA ACTING ON THE TIGHT THRML
GRADIENT AT H7 ACRS THE AREA FM CONFLUENT UPPR LVL FLOW SHLD GET
PRECIP GOING LATER THIS EVNG TO OUR W. THIS IS LIKELY TO MV INTO
OUR WRN FA ARND MIDNIGHT. PRECIP WL LIKELY START INITIALLY AS SOME
-RA/SN MIX ACRS THE ENTIRE REGION. PRECIP WL HAVE A VRY HARD TIME
MOVING EWD TONIGHT WITH THE VRY DRY AIR OVR IA BEING ADVECTED WWD.
THIS IS VRY VISIBLE IN THE LOWER TEEN SFC DEW POINTS OVR THIS
AREA. THUS PRECIP MAY NOT MAKE IT TO A OMA TO AFK TO FNB LINE
UNTIL AFTN 09Z. PRECIP ACRS OUR NW FA SHLD SWITCH TO SNOW FAIRLY
QUICKLY WITH THE SRN CWA DOING THE SAME BY MRNG. HAVE PUSHED BACK
THE START TIME OF THE WRNG OVR THE NW FA TO MIDNIGHT TO MATCH THE
ONSET OF PRECIP. HAVE ALSO REMOVED THE IA COUNTIES FM THE ADVRY
WITH LITTLE OR NO SN EXPECTED THERE. DID EXTEND THE ADVISORY S TO
THE KS/NEB BORDER WITH THIS PACKAGE. FORCING IS PROGGED TO CONT
THRU THE DAY ON SUN OVR MOST OF THE FA SEEN IN THE H7
FRONTOGENESIS AND ISENTROPIC ANALYSIS. MID LVLS DO TEND TO DRY
THOUGH IN THE SRN FA AND WL CONT TO MENTION SOME SLEET OR EVNG A
LITTLE -RA IN THE AFTN THERE. OTHERWISE THE NW IS LIKELY TO STAY
SN. HEAVIES SN IS LIKELY TO FALL FM ARND 09Z THRU 18Z SUN. DID CUT
BACK ON THE AMNTS IN THE NW FA BASED ON THE INITIAL -RA MIX AND
LOOKING AT THE STRENGTH OF THE LIFT.

AS MAIN UPPR LVL SYSTEM STARTS TO EDGE EWD SUN NIGHT...LO LVL FLOW
BACKS TO THE E...AND WE BRING IN EVEN DRIER AIR TO THE AREA. THUS
PRECIP IS LIKELY TO END FOR ALL BY OUR FAR W AND SW FA FOR MOST OF
THE NIGHT. MODELS ARE CONSISTENT IN THE MAIN UPPR LVL SYSTEM
MOVING INTO THE PLAINS ON MON TAKING A TRACK THRU KS AND INTO MO
BY TUES MRNG. UPPR LVL Q-G FORCING IS VRY STG ON MON AND A VERY
GENEROUS PRECIP SHIELD SHLD DVLP LATE SUN NIGHT OVR KS AND PUSH
NWD ON MON MRNG INTO THE FA. WE ARE STILL GOING TO BE FIGHTING THE
DRY AIR OVR THE FA...AND THIS IS STILL EXPECTED TO BRING A VRY
TIGHT GRADIENT TO THE SNOWFALL. GFS QFP CONTS TO APPEAR
UNREASONABLE...AND ALTHOUGH THE MODEL DYNAMICS SEEM
REASONABLE...WILL USE MORE OF THE NAM FOR PRECIP ORIENTATION. THUS
SN...SOME POSSIBLY HEAVY SHLD MV NWD THRU ABOUT I-80 BY EARLY
AFTN. HAVE REDUCED POPS TO CHC IN THE N AND REMOVED MOST OF THE SN
ACCUM FOR THERE. SWD...GIVEN THE DEGREE OF LIFT AND DURATION OF THE
EVNT...A VRY SIG SN STORM SEEMS IN THE CARDS. HAVE ISSUED A WINTER
STORM WATCH FOR COUNTIES FM OLU TO OMAHA AND SWD FOR MON AND MON
NIGHT WHEN THE HEAVIES OF THE SNOW IS EXPECTED. H85 WINDS INCREASE
ON THE NAM TO 60 KTS OVR THE SRN FA ON MON...WHICH MAY LEAD TO SOME
15 TO 25 MPH WITH GUSTS TO 30 MPH AT THE SFC. ALTHOUGH WE ARE
EXPECTED A FAIRLY WET SNOW...THERE MAY BE SOME ISSUES WITH BLOWING
AND DRIFTING BY MON. ALTHOUGH MODEL QPF GRAPHICS SHOW EXTREME
AMOUNTS FOR OUR FA...WL CONT TO TAKE MORE OF A CAUTIOUS APPROACH
ATTM GIVEN THE VRY TIGHT GRADIENT AND THE AMOUNT OF DRY AIR.
SYSTEM WL EXIT THE REGION ON MON NIGHT WITH SN COMING TO AN END FM
N TO S BY TUES MRNG.

EXTENDED...MAIN CHALLENGE THROUGH THIS PERIOD WILL BE
TEMPERATURES CONSIDERING THE HEFTY SNOW PACK THAT WILL BE ON THE
GROUND...AND A SECONDARY CHANCE OF SNOWFALL AGAIN WEDNESDAY
AFTERNOON THROUGH THURSDAY MORNING. THIS NEXT SYSTEM DOESN/T HAVE
NEAR THE POTENCY THAT THE FIRST TWO STORMS WILL POSE...BUT
NEVERTHELESS STILL LOOKS LIKE ABOUT A 30 TO 40 PERCENT CHANCE.
GENERALLY WENT BELOW GUIDANCE VALUES THROUGH THE PERIOD WITH THE
COLDEST READINGS MORNING WEDNESDAY MORNING AS HIGH PRESSURE SHOULD
ALLOW FOR QUICK RADIATIVE COOLING TUESDAY EVENING BEFORE WEAK
RETURN FLOW SETS UP BY WEDNESDAY MORNING. LATER IN THE PERIOD BY
FRIDAY AND SATURDAY...GOOD WARMING ALOFT IS EXPECTED AS AN UPPER
RIDGE BEGINS TO BUILD ACROSS THE PLAINS WITH GOOD DOWNSLOPING
POTENTIAL. HIGHS SHOULD SLOWLY WARM...REACHING THE LOWER TO MID
40S BY SATURDAY WHICH WILL DEFINITELY HELP THE SNOW TO MELT. WHILE
IT/S TOO SOON TO PREDICT WITH ANY CERTAINTY...THERE COULD BE SOME
PATCHY DENSE FOG DURING THE NIGHTTIME HOURS LATER IN THE WEEK DUE
TO INCREASED BOUNDARY LAYER MOISTURE AND HIGH PRESSURE
OVERHEAD...BOTH FRIDAY AND SATURDAY MORNINGS.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT
     FOR NEZ030-NEZ042-NEZ043-NEZ044-NEZ045-NEZ050-NEZ051-NEZ052-
     NEZ053-NEZ065-NEZ066-NEZ067-NEZ068-NEZ078-NEZ088-NEZ089-
     NEZ090-NEZ091-NEZ092-NEZ093.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST SUNDAY
     FOR NEZ044-NEZ045-NEZ050-NEZ051-NEZ052-NEZ053-NEZ065.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST SUNDAY
     FOR NEZ066-NEZ067-NEZ078-NEZ088-NEZ089.

     SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST SUNDAY FOR
     NEZ012-NEZ015-NEZ018-NEZ032-NEZ033-NEZ034-NEZ043.

     WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST SUNDAY
     FOR NEZ011-NEZ016-NEZ017-NEZ030-NEZ031-NEZ042.

IA...WINTER STORM WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT
     FOR IAZ069-IAZ079-IAZ080-IAZ090-IAZ091.

&&

$$

BOUSTEAD/DEWALD


[senorpepr]

Looking at the raw model data, I would go with 8-12" total at this time...

We'll have to see how much this dry air in Iowa kills the storm -- it's MUCH too dry for a winter storm.