Area Forecast Discussion
Issued by NWS Des Moines, IA

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123
FXUS63 KDMX 022345
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
545 PM CST TUE FEB 2 2016

.UPDATE...
ISSUED AT 545 PM CST TUE FEB 2 2016

DENSE FOG HAS DEVELOPED ACROSS OUR SOUTHERN AND SOUTHEASTERN
COUNTIES...AND IT IS ANTICIPATED THAT IT WILL PERSIST UNTIL WINDS
PICK UP LATER TONIGHT. THEREFORE WE HAVE ISSUED A DENSE FOG
ADVISORY FOR THOSE AREAS THROUGH MIDNIGHT. SOME AREAS WILL IMPROVE
BEFORE THEN AND THE ADVISORY WILL BE TRIMMED DOWN AS NEEDED.

&&

.SHORT TERM /TONIGHT/...
ISSUED AT 301 PM CST TUE FEB 2 2016

PRIMARY CONCERN TONIGHT WILL BE PRECIP TRENDS AND HEADLINE
ADJUSTMENTS. POWERFUL LONG WAVE TROUGH WITH NOTED PV ANOMALY IN THE
CORE CONTINUES TO AFFECT IA THIS AFTERNOON WITH IMPRESSIVE 170KT JET
LEADING THE WAY. LEFT EXIT REGION DIVERGENCE AND DPVA CONTINUE TO
PUSH PRIMARY LIFT ZONE WELL NORTH AND EAST OF IOWA.
STRONG DEEP QG FORCING...INCLUDING LOWER LEVEL THERMODYNAMIC
SUPPORT...ALSO LINGERS BACK INTO IA BUT THIS IS SOMEWHAT MOISTURE
STARVED AND IS CURRENTLY GENERATING NOTHING BEYOND LIGHT SNOW AND
THEN DRIZZLE FARTHER SOUTH WHERE ICE INTRODUCTION IS LACKING. THUS
MUCH OF OUR PRECIP HAS ENDED FOR THE TIME BEING. A CONSIDERABLE
AMOUNT OF BLOWING SNOW LINGERS NORTH IN THE HEAVIER SNOW BAND
HOWEVER...6 INCHES PLUS GENERALLY ALONG AND NORTH OF SAC
CITY...WEBSTER CITY...MASON CITY LINE...WITH BLIZZARD OR NEAR
BLIZZARD CONDITIONS STILL BEING REPORTED BY LAW ENFORCEMENT...SOCIAL
MEDIA...DOT PLOW CAMS...ETC.

PRECIP MAY NOT BE FINISHED OVERALL HOWEVER AS DEFORMATION ZONE WILL
STILL LIFT THROUGH CENTRAL AND NORTHERN PORTIONS OF THE FORECAST
AREA...AND MUCH LIKE DEPICTED YESTERDAY BY THE NAM AND ASSOCIATED
NMM CORE MODELS...A LOW STATIC STABILITY BURST OF PRECIP MAY OCCUR
NEAR THE LOW CENTER WHICH IS CURRENTLY IN THE KS/NE/IA NEIGHBORING
BORDERS. TOKEN MUCAPES ARE NOTED IN THIS AREA CURRENTLY SO IT IS
QUITE POSSIBLE WE SEE ANOTHER ROUND OF SHOWERY WINTRY PRECIP LATER
THIS EVENING JUST EAST OF THE DEF ZONE. MOST DOMINATE PRECIP TYPE
SEEMS TO BE SNOW...AND WE MAY SEE ANOTHER INCH OR TWO OF SNOW WITH
ANOTHER STRONG WIND SURGE FOLLOWING IMMEDIATELY BEHIND. THUS EVEN
THOUGH WINDS MAY DIMINISH SOMEWHAT THIS EVENING AS THE LOW
APPROACHES SERN IA...EXPECT A SHARP INCREASE AGAIN OVERNIGHT.

WHAT THIS MEANS FOR HEADLINES IS THAT WINTER WEATHER ADVISORY AND A
TIER OF THE WINTER STORM WARNING WILL BE CANCELLED. THERE WILL BE A
CONSIDERABLE LULL IN SENSIBLE WEATHER INTO THE EVENING IN THESE
LOCATIONS. ADDITIONAL HEADLINES COULD POTENTIALLY BE NEEDED
AGAIN...BUT THIS WOULD BE DEPENDENT ON ADDITIONAL PRECIP. THE SNOW
CONSISTENCY IN CENTRAL IA IS VERY WET AND NOT CONDUCIVE FOR
SIGNIFICANT BLOWING SNOW. FARTHER NORTH WHERE THE SNOW IS DEEPER AND
DRIER AND CURRENTLY BLOWING...ANOTHER INCREASE IN WINDS WITH GUSTS
LIKELY 35-40 MPH WILL LOOK TO PRODUCE ANOTHER ROUND OF BLIZZARD OR
NEAR BLIZZARD CONDITIONS. SO EVEN THOUGH THERE MAY BE A LULL...WILL
LEAVE THE BLIZZARD WARNING UNCHANGED AS TO NOT INJECT CANCELLED
WORDING AND FALSE MESSAGING.

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 301 PM CST TUE FEB 2 2016

RELATIVELY QUIET IN THE LONG TERM PERIOD. FOR THE START OF THE
PERIOD...THE LAST OF THE DEFORMATION ZONE PRECIP WILL BE EXITING
THE EASTERN PORTION OF THE FORECAST AREA AND WILL BE OUT OF THE
AREA BY 18Z. LITTLE TO NO ACCUMULATION EXPECTED AFTER 12-13Z.
WINDS HOWEVER WILL STAY UP. WE ARE LOOKING AT WINDS IN THE MORNING
IN THE RANGE OF 15 TO 30 MPH AND THIS WILL CONTINUE TO PRODUCE
AREAS OF BLOWING SNOW...ESPECIALLY NW WHERE WE HAVE THE MOST NEW
SNOW. IT WILL ALSO BE MUCH COLDER SO EVEN THOUGH WE WILL NOT HAVE
SNOW TO CONTEND WITH IT WILL BE A RAW DAY. THERE MAY ALSO BE SOME
RESIDUAL TRAVEL CONCERNS AS MELTED ROADWAYS SLICKEN UP WITH THE
COLDER TEMPS AND WHEEL TRACK PRODUCE A GLAZE FROM DRIFTING SNOW
ACROSS THE ROADS.

ON THURSDAY THERE IS ANOTHER SHORTWAVE THAT GRAZES THE FORECAST
AREA ACROSS THE NORTHEAST. AT THIS POINT I LEFT THE FORECAST DRY
BUT WE COULD SEE A DUSTING OF SNOW IN THE MASON CITY AREA AND
LOCATIONS SOUTH AND EAST OF THE CITY.

FOR THE REST OF THE PERIOD UPPER RIDGING WORKS INTO THE AREA AND A
MORE WESTERLY FLOW DEVELOPS BRINGING IN WARMER...OR AT LEAST
MODERATING TEMPERATURES BACK TO THE AREA. SOUTHERN LOCATIONS COULD
SEE READINGS IN THE 40S WITH MID TO UPPER 30S NORTH OVER THE
WEEKEND.

THEN FOR SUNDAY THROUGH TUESDAY THE MODELS DROP ANOTHER DEEP
TROUGH OVER THE UPPER MIDWEST BRINGING COLDER TEMPERATURES BACK TO
CENTRAL IOWA ALONG WITH A CHANCE FOR SOME LIGHT SNOW. THIS SYSTEM
WILL LACK THE GULF MOISTURE TAP SO DESPITE THE SYSTEM BEING STRONG
AND MUCH COLDER AIR MOVING IN...WE ARE NOT LOOKING AT A LOT OF
SNOW WITH THE SYSTEM.

&&

.AVIATION...03/00Z
ISSUED AT 545 PM CST TUE FEB 2 2016

IFR CONDITIONS WILL PERSIST THROUGH THE NIGHT...EXCEPT FOR
POSSIBLY A BREAK OF A FEW HOURS AT OTM AROUND OR JUST AFTER
MIDNIGHT. LIGHT RAIN/SNOW WILL ALSO AFFECT MOST OF THE TERMINALS
OVERNIGHT WITH LIGHT ACCUMULATIONS. TOWARD WEDNESDAY
MORNING...ESPECIALLY AFTER SUNRISE...THERE WILL BE A GRADUAL
IMPROVEMENT IN VSBYS AND CIGS...BUT BLSN MAY CONTINUE TO CAUSE
SOME ISSUES AT FOD/MCW.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ADAIR-ADAMS-
APPANOOSE-CLARKE-DAVIS-DECATUR-JASPER-LUCAS-MADISON-MAHASKA-
MARION-MONROE-POLK-POWESHIEK-RINGGOLD-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.

WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR AUDUBON-BOONE-
BREMER-BUTLER-DALLAS-GUTHRIE-HARDIN-STORY.

BLIZZARD WARNING UNTIL 6 AM CST WEDNESDAY FOR CALHOUN-CARROLL-
CERRO GORDO-CRAWFORD-EMMET-FRANKLIN-GREENE-HAMILTON-HANCOCK-
HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT.

&&

$$

UPDATE...LEE/CURTIS
SHORT TERM...SMALL
LONG TERM...FAB
AVIATION...LEE



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