Alert archive / Iowa / Winter Storm Watches in 2011
Winter Storm Watch 4, NWS Des Moines, IA
NWS Des Moines, IA issued this winter storm watch at Feb 18, 2011, 3:48 PM CST for 7 counties in Iowa. It took effect at Feb 20, 2011, 12:00 AM CST. It was in force for .
The area
The counties it named.
The facts
- Issued
- Feb 18, 2011, 3:48 PM CST (21:48 UTC)
- In effect from
- Feb 20, 2011, 12:00 AM CST
- Expired
- Feb 19, 2011, 4:20 PM CST
- In force
- Issued by
- NWS Des Moines, IA
Counties Cerro Gordo County, IA, Emmet County, IA, Hancock County, IA, Kossuth County, IA, Palo Alto County, IA, Winnebago County, IA, Worth County, IA
The radar
The Des Moines radar (KDMX), 167 km from the middle of the area, began a volume at 21:49 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 12:00Z, 9.8 hours before the alert went out and 183 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 895 m above ground
- 0-6 km bulk shear
- 71 kt
- 0-1 km storm-relative helicity
- 31 m²/s²
- 0-3 km storm-relative helicity
- 60 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this winter storm watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Des Moines, IA wrote its last area forecast discussion before this winter storm watch went out at Feb 18, 3:35 PM CST, 13 minutes earlier.
Area forecast discussion, Feb 18, 3:35 PM CST, 13 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 335 PM CST FRI FEB 18 2011 SHORT TERM /TONIGHT/... LITTLE SENSIBLE WEATHER FOR OVERNIGHT. WEAK RIDGE KEEPS ZONAL FLOW ACROSS IOWA...WITH ABOVE NORMAL TEMPERATURES. HAVE TWEAKED OVERNIGHT LOW TEMPERATURES UP A FEW DEGREES WITH WEAK WAA AND INCREASING CLOUDS. WINDS WILL SHIFT TO THE EAST AROUND MIDNIGHT WITH VERY WEAK FRONTAL PASSAGE. MOISTURE IS EXTREMELY LIMITED...SO FRONT WILL PASS WITHOUT IMPACT. STORM SYSTEM PUSHING EAST WILL BEGIN TO AFFECT REGION SLIGHTLY...WITH MIDLVL MOISTURE INCREASING AFTER FRONTAL PASSAGE. THIS WILL INCREASE CLOUD COVER ACROSS THE AREA BY EARLY MORNING. LONG TERM /SATURDAY THROUGH FRIDAY/... STRONG UPR LVL LO PRES MOVING ONSHORE IN THE SW U.S. WILL BE THE WEATHER MAKER FOR THIS WEEKEND. PLENTY OF DYNAMICS WITHI THIS FEATURE AND MDLS HAVE HAD A DIFFICULT TIME HANDLING THE SYS. LAST NIGHT THE ECMWF AND GFS SWITCHED PLACES WITH POSITION/TRACK OF THE LOW. TODAY THE RUNS ARE MUCH CLOSER TOGETHER AND IT APPEARS THE GFS HAS A PRETTY GOOD HANDLE ON THE TRACK AT THIS POINT. PLENTY OF WARM AIR AND MOISTURE WILL BE DRAWN NORTH AS THE SYS LAST NIGHT DID NOT SCOUR OUT THE MOISTURE. THIS TIME THERE WILL BE MORE FOR THE SYSTEM TO WORK WITH. STRONG THETA-E ADVECTION WILL MOVE INTO THE CWA SAT NGT INTO SUN. EXPECT TO SEE A SHARP GRADIENT IN TEMPERATURE WITH THIS STORM WITH MOST OF THE AREA NORTH OF THE TRACK REMAINING NEAR OR BLO FREEZING. THINKING IS THAT THE HEAVIER SNOW WILL BE TO THE NORTH OF THE STATE WITH FREEZING RAIN BEING THE MAIN PROBLEM FOR IA. HAVE OPTED TO GO WITH A WINTER STORM WATCH FROM MIDN SAT NGT UNTIL MON MRNG WITH THE MAIN THREAT FOR BEING ICE ACRUAL. A 3-6 TENTHS INCH ACRUAL IS NOT OUT OF THE QUESTION. THE POSSIBLE SAVING GRACE IS THAT DURING THE DAY SUN...TEMPS MAY PUSH JUST ABOVE FREEZING AND MELT OFF SOME OF IT BEFORE THE COLDER AIR MOVES IN BHND THE STORM. TOTAL SNOW ACCUM OVER THE FAR NORTH SHOULD BE UNDER 2 INCHES...WITH LITTLE ACCUM FARTHER SOUTH. HI PRES WILL BUILD INTO THE STATE BY LATER MON INTO MID WEEK WITH TEMPS FALLING TO AOB NORMAL FOR A FEW DAYS. WARMING IS EXPECTED FOR THE LATER PART OF THE WEEK...BUT ANOTHER WEATHER SYSTEM WILL BRING A CHANCE OF PCPN TO THE STATE. THINKING AT THIS POINT IS THAT THIS STORM WILL BRING MIXED RASN INSTEAD OF FREEZING PCPN. && AVIATION...18/18Z VFR CONDITIONS WILL PERSIST ACROSS ALL SITES THROUGHOUT THE PERIOD...WITH WEAK RIDGE. WINDS WILL SHIFT TO THE EAST OVERNIGHT WITH WEAK FRONTAL PASSAGE. LARGE AREA OF LOW PRESSURE WILL PUSH INTO REGION AT END OF PERIOD. THIS WILL BRING INCREASE IN MID LEVEL MOISTURE...WITH CEILINGS DROPPING TO THE LOW END OF VFR. WINDS WILL ALSO SWING TO THE SOUTH WITH APPROACHING SYSTEM...INCREASING BY 18Z. && HYDROLOGY... RECENT WARM WEATHER AND SNOW MELT RUNOFF WILL CONTINUE TO HELP BREAK UP ICE ALONG AREA RIVERS AND STREAMS INTO SUN. THE THREAT FOR ICE JAMS WILL CONTINUE THROUGH THE PERIOD WITH THE POTENTIAL FOR FLASH FLOODING AS WATER BACKS UP AND RISES RAPIDLY BEHIND THESE JAMS. THE ICE JAMS TYPICALLY OCCUR NEAR SHARP BENDS IN STREAMS WHERE ICE CAN BECOME HUNG UP. IN ADDITION...A ROUND OF WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS IS EXPECTED SATURDAY NIGHT AND SUNDAY. RAINFALL AMOUNTS OF ONE HALF TO ONE INCH ARE FORECAST OVER CENTRAL MUCH OF THE STATE. THIS PRECIPITATION WILL CAUSE FURTHER RISES ON ALREADY NEAR BANKFULL STREAMS AND COULD CAUSE FURTHER ICE ACTION. MUCH OF THE ICE HAS BEEN FLUSHED OUT OF THE RIVERS OVER SOUTHERN IOWA...BUT HAS YET TO BE FLUSHED OUT OVER PARTS OF THE CENTRAL AND MOST OF THE NORTHERN COUNTIES. TEMPERATURES WILL BE CLOSE TO FREEZING OVER THE NORTH...WITH MOST OF THE PRECIPITATION FALLING AS FREEZING RAIN OR SNOW. THESE TWO FACTORS WILL TEND TO MINIMIZE THE ICE ACTION FROM THE FAR NORTH. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH LATE SUNDAY NIGHT FOR CERRO GORDO-EMMET-HANCOCK-KOSSUTH-PALO ALTO-WINNEBAGO- WORTH. && SHORT TERM...WILKINS LONG TERM...MS FEB 11 AVIATION...WILKINS HYDROLOGY...MS FEB 11
Hazardous weather outlook, Feb 18, 4:50 AM CST, 10 hours 58 minutes before
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</html>The office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 18, 12:05 AM CST | River Flood Warning | DMX | Mahaska, Marion | 6 hr |
| Feb 18, 5:39 AM CST | River Flood Warning | DMX | Emmet | 12 hr |
| Feb 18, 5:06 PM CST | River Flood Warning | DMX | Black Hawk, Butler | 28 hr |
Nearby
Winter Storm Watches in Iowa, 2011Every winter storm watch in 2011
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.