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January 10th-12th OV/MW/GL Winter Storm prospects


Harry

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I'm thinking in excess of 4 inches now 20 miles west of the loop...:snowman:

I'm sticking with a general 2-4" across northern IL with perhaps some isolated higher amounts. Best chance of 4" or more looks like it's near the lake where there could be some totals over 4". The winds are very light so it would probably stay very close to the shore, but there's a window where the thermodynamics look decent before the low level winds shift the activity farther east.

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You're exaggerating.

It's fairly similar.

You can compare the H5 charts, H7 charts to the RUC and the current radar to the 18z NAM and see what is going on.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/ruc/hr3/images/ruc_500_012l.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_500_012l.gif

If the H5 chart at midnight looks anything like the NAM has it. I would really shocked.

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ILN sticking to their guns.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE WILMINGTON OH

330 PM EST MON JAN 10 2011

.SYNOPSIS...

A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE TENNESSEE VALLEY TODAY.

THE LOW WILL THEN LIFT NORTHEAST THROUGH THE UPPER OHIO VALLEY ON

TUESDAY. AS IT EXITS...NORTHWEST FLOW WILL SET UP OVER THE REGION

AND SCATTERED SNOW SHOWERS WILL BE FOUND THROUGH WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...

THOUGH A FEW BREAKS IN THE HIGHER DECK MAY BE FOUND EARLY THIS

EVENING AM LOOKING FOR INCREASING MOISTURE FROM THE TOP DOWN

OVERNIGHT. LOWERED THE CHANCE FOR SNOW THROUGH MIDNIGHT BUT THEN

LET IT RAMP UP PRETTY QUICKLY TOWARDS DAYBREAK. THINK THAT IT WILL

TAKE A WHILE FOR THE ATMOSPHERE TO SATURATE TONIGHT AND THE BRUNT

OF THE WEATHER WILL OCCUR TOWARDS DAYBREAK.

A VERY SLOW DROP IN TEMPS WILL OCCUR TONIGHT AND I TOOK THE

TEMPERATURES TO BLEND WITH THE PREVIOUS FORECAST AND WARMER MET

GUIDANCE.

REGARDING THE WARNING/ADVISORY...DID NOT CHANGE THE FORECAST.

THINK THAT EVERYONE WILL FEEL IMPACT FROM THIS AND THE SNOW WILL

START FLYING LATER TONIGHT.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...

WINTER STORM WILL TRACK THROUGH THE REGION WITH THE LIONS SHARE OF

SNOW OCCURRING DURING THE DAY...TAPERING TO LIGHT SNOW IN THE

EVENING. TRANSITIONED THE SNOW TO SNOW SHOWERS ON WEDNESDAY WITH

NORTHWEST FLOW OFF OF LAKE MICHIGAN AND A FAIRLY MOIST LOW LEVELS.

DEPENDING ON WHERE ANY UPPER LEVEL DYNAMICS ARE PRESENT DURING THE

DAY AND A PASSAGE OF A SECONDARY TROUGH IN THE EVENING...

SCATTERED SNOW SHOWERS WILL BE PREVALENT WITH LIGHT ADDITIONAL

ACCUMULATIONS RANGING FROM A QUARTER INCH TO AN INCH.

TOOK TEMPERATURES TO BE IN LINE WITH THE COOLER MAV GUIDANCE.

THOUGHT THAT THE MET WAS WAY TOO WARM IN NORTHWEST FLOW AND A

FRESH SNOW PACK...ESPECIALLY TOWARDS THE END OF THE PERIOD. WED

NIGHT MET GUIDANCE WAS 8-9 DEG HIGHER THAN WHAT WAS IN FORECAST

AND MAV GUIDANCE. BLENDED MAV AND PREV FCST FOR LATER PERIODS.

BELIEVE THAT THE TRACK OF THE H8 LOW WILL DICTATE THE HEAVIEST

SNOWFALL AMOUNTS...GENERALLY 5 INCHES. THINK THAT A GOOD 2-3

INCHES WILL BE FOUND SOUTH OF THE OHIO RIVER AND THE WATCH IS IN

EFFECT WHERE WE HAVE 3-4 INCHES OVER THE SOUTHERN HALF OF CWA. WSW

CRITERIA IS SPLIT...SO NORTHERN CWA WILL REMAIN IN ADVISORY AND

NOT BE UPGRADED TO A WARNING.

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You can compare the H5 charts, H7 charts to the RUC and the current radar to the 18z NAM and see what is going on.

http://www.nco.ncep....uc_500_012l.gif

http://www.nco.ncep....am_500_012l.gif

If the H5 chart at midnight looks anything like the NAM has it. I would really shocked.

We're pretty much in nowcast....I'll be watching that area of heaviest precip over central MO. According to the nam it tracks into central IL then into n. IN. That should tell us whether the nam is cracked or not.

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LOT

CLOSED UPPER LOW CENTERED OVER EASTERN MONTANA THIS AFTERNOON...

WITH RATHER STRONG SHORT WAVE TROUGH ROTATING AROUND THE SOUTHERN

PERIPHERY INTO THE LOWER MISSOURI VALLEY PER GOES WATER VAPOR.

DIFFUSE AREA OF LOW PRESSURE OVER SOUTHWEST MISSOURI AND INVERTED

TROUGH EXTENDING UP THE MO VALLEY ARE REFLECTIONS OF LIFT PROVIDED

BY THIS SHORT WAVE...AND NICE AREA OF DIFFLUENCE AND UPPER

DIVERGENCE ALONG NORTH/NORTHEAST SIDE OF MID/UPPER LEVEL JET.

GUIDANCE REMAINS IN VERY GOOD AGREEMENT IN DEVELOPING MORE ORGANIZED

SFC LOW OVER THE LOWER OHIO VALLEY THROUGH TUESDAY MORNING AS MAIN

SHORT WAVE CONTINUES TO TRACK EAST AND DEEPEN. REGIONAL RADAR MOSAIC

AND MIDWEST SFC OBS INDICATE AREA OF SNOW HAS DEVELOPED FROM

KS/MO/IA AND SOUTHERN MN AT THIS TIME...AND THIS EXPECTED TO

CONTINUE TO SPREAD EAST INTO WESTERN IL THIS EVENING. ANALYSIS OF

VARIOUS MODEL SOLUTIONS INDICATES STRONGEST FORCING ACROSS THE AREA

WILL COME TONIGHT AND EARLY TUESDAY...THOUGH WITH RETREATING SFC

HIGH ACROSS THE UPPER LAKES AND ONTARIO...DRY EASTERLY LOW LEVEL

FLOW WILL TAKE SOME TIME TO SATURATE. FORCING ALONG NORTHERN PART OF

DISTURBANCE IS ALSO EXPECTED TO WEAKEN WITH TIME TUESDAY...AS MAIN

VORT PROPAGATES THROUGH THE OHIO VALLEY AND CLOSED UPPER LOW TO THE

NORTHWEST BECOMES MORE SHEARED OUT. BASED ON TRACK OF MAIN VORT AND

SFC LOW ALONG THE OHIO RIVER...GREATEST SNOW ACCUMULATION EXPECTED

TO BE GENERALLY SOUTH OF THE FORECAST AREA FROM MISSOURI INTO

CENTRAL/SOUTHERN PORTIONS OF IL/IN/OH. STILL...ACCUMULATING SNOW

ANTICIPATED ACROSS WFO LOT FORECAST AREA...WITH AN BLEND OF MODEL

QPF AMOUNTS SUPPORTING GENERALLY 2-4" ACROSS THE NORTHERN 2/3 OF THE

CWA AND 3-5" AMOUNTS ACROSS THE SOUTH. SOME QUESTION REMAINS ABOUT

POTENTIAL FOR A LITTLE LAKE ENHANCEMENT WITH E/NE FLOW INTO

NORTHEAST IL TUESDAY. FORECAST SOUNDINGS DO DEPICT WEAK LAKE INDUCED

INSTABILITY OVER THE LAKE...THOUGH LIGHT LOW LEVEL WIND FIELD MAY

NOT ALLOW FOR APPRECIABLE MOISTURE FLUX TO THE DEGREE THAT SNOW

AMOUNTS WOULD BE TOO MUCH HIGHER. HAVE INDICATE SLIGHTLY HIGHER

AMOUNTS IN LAKESIDE COUNTIES...BY A FEW TENTHS OF AN INCH.

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FWIW, GRR does briefly mention the dry air being a problem, but like I said it's a miniscule and brief mention.

However, what they did emphasize is the possibility of higher amonts (in SC/SE Michigan) if the transfer takes longer than expected. Also advisories would likely be neded for Jackson/Lansing, but I believe they're waiting another cycle to be sure.

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Yeah, they are saying around an inch for the Saginaw Valley but I think that is on the low side. They have a total of 2-3 inches here in the zones.

Yeah it seems strange for sure especially there where you are as i would *think* moisture off of Huron could help a little?

Parts of the AFD from GRR.

THIS IS NOT A LAKE EFFECT SNOW EVENT, AND WILL BE UNLIKE THE

THURSDAY THROUGH SUNDAY TIME FRAME WHEN MOST OF THE SNOW FELL WEST

OF HIGHWAY 131. ACTUALLY, THE HIGHEST ACCUMULATIONS FOR THIS STORM

ARE EXPECTED TO BE SOUTH AND EAST OF GRAND RAPIDS WHERE 3 TO 5 INCH

TOTALS ARE POSSIBLE. AMOUNTS OF 1 TO 3 INCHES ARE ANTICIPATED NORTH

AND WEST OF GRAND RAPIDS.

HE MAIN CONCERN IS TOTAL SNOWFALL AMOUNTS FOR TUESDAY AND TUESDAY

NIGHT. IT SEEMS THE CRUX OF PROBLEM IS HOW SOON THE EAST COAST LOW

TAKES OVER AS THE MAIN SYSTEM. THE LONGER THAT TAKES, THE MORE SNOW

IS POSSIBLE IN SOUTH CNTRL AND SE LWR MI. ADVISORIES MAY BE NEEDED

FOR THE LANSING AND JACKSON AREAS, ESPECIALLY SINCE IT APPEARS THE

TUE EVENING COMMUTE COULD BE HIGHLY IMPACTED.

CLOSED UPPER LOW NOW OVER ERN MONTANA IS PROGGED TO TRACK TO NEAR

YOUNGSTOWN OHIO BY 06Z WEDNESDAY. INITIALLY THE SFC REFLECTION IS AN

INVERTED TROUGH, ALTHOUGH THE MODELS ARE SHOWING A CLOSED CONTOUR

SFC LOW EVENTUALLY FORMING OVER SRN IL BY 12Z TUE AND DEEPENING A

BIT AS IT TRACKS NE TOWARD WRN PA BY 06Z WED. THE POTENTIAL EXISTS

FOR A DECENT TROWAL FEATURE TO IMPACT THE SE PORTION OF THE GRR

CWFA... INCLUDING LAN AND JXN... DURING THE TUESDAY EVENING COMMUTE.

THE NAM IS MORE AGGRESSIVE THAN THE GFS IN TERMS OF QPF AND SNOW

AMOUNTS... AND OPTED ATTM FOR A BLEND OF THE TWO. DRY AIR IN THE LOW

LEVELS MAY DELAY THE ONSET OF THE SNOW WHICH COULD CUT DOWN A BIT ON

TOTAL AMOUNTS.

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It looks like it will take much of the day just to saturate the atmosphere around here. The eastward progress of the actual snowfall is painfully slow. Ottumwa finally just reported light snow.

friv might have a point about the 18z nam. I just checked and it shows a pretty good thump for the western and central parts of IA at hour 6z and 12z. Here's the current radar loop. Doesn't look too promising, unless it's expected to really start filling in fast.

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?radar_us+/2h/

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Zone forecast has me at 4-6 inches. :thumbsup:

ZONE FORECAST PRODUCT

NATIONAL WEATHER SERVICE WILMINGTON OH

355 PM EST MON JAN 10 2011

OHZ051>053-061-062-110945-

MIAMI-CHAMPAIGN-CLARK-MONTGOMERY-GREENE-

INCLUDING THE CITIES OF...PIQUA...URBANA...SPRINGFIELD...DAYTON...

XENIA

355 PM EST MON JAN 10 2011

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 AM TUESDAY TO

MIDNIGHT EST TUESDAY NIGHT...

.TONIGHT...CLOUDY. A 50 PERCENT CHANCE OF SNOW...MAINLY LATE.

LOWS 15 TO 20. NORTHEAST WINDS AROUND 10 MPH.

.TUESDAY...SNOW. ACCUMULATION OF 2 TO 4 INCHES. HIGHS IN THE MID

20S. NORTHEAST WINDS 5 TO 10 MPH. CHANCE OF SNOW 100 PERCENT.

.TUESDAY NIGHT...CLOUDY. SNOW LIKELY IN THE EVENING...BECOMING

SCATTERED AFTER MIDNIGHT. TOTAL ACCUMULATION OF 4 TO 6 INCHES

POSSIBLE. LOWS 15 TO 20. WEST WINDS 10 TO 15 MPH. CHANCE OF SNOW

60 PERCENT.

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