Area Forecast Discussion
Issued by NWS Des Moines, IA

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400
FXUS63 KDMX 041743
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1143 AM CST THU FEB 4 2016

.UPDATE...
ISSUED AT 1142 AM CST THU FEB 4 2016

OVERALL MINIMAL CLOUD AND WEATHER MODIFICATIONS WITH THIS NOON
UPDATE. COMPACT PV ANOMALY OVER THE SIOUXLAND WILL RACE
SOUTHEASTWARD THIS AFTERNOON ACROSS NORTHERN IOWA. MARGINAL DGZ
FORCING AND MOISTURE COMBINED WITH WEAK STATIC STABILITY SHOULD BE
ENOUGH TO FUEL SCATTERED FLURRIES OVER NORTHERN IOWA...BUT NO
IMPACTS ARE EXPECTED. KFSD STILL SHOWS POCKETS OF SNOW SHOWERS IN
FAR SOUTHWEST MN...BUT TRENDS DOWNSTREAM ARE HARD TO JUDGE GIVEN
THE SHALLOW NATURE OF THE CELLS AS THEY MOVE FARTHER FROM THE RDA.

&&

.SHORT TERM /TODAY/...
ISSUED AT 333 AM CST THU FEB 4 2016

BROAD NORTHWEST FLOW WILL PERSIST ACROSS THE REGION THROUGH NEXT
WEEK WITH SEVERAL DIFFERENT SYSTEM SET TO AFFECT THE STATE.
INITIALLY...WARM ADVECTION UNDERWAY EARLY THIS MORNING WITH MID
AND HIGH CLOUDS MOVING INTO THE STATE. THIS IN ADVANCE OF
APPROACHING SHORTWAVE. FORCING AND ASSOCIATED LIFT WILL INCREASE
BY LATE MORNING BUT SYSTEM IS OVERALL STARVED FOR MOISTURE. A FEW
FLURRIES/VERY LIGHT SNOW MAY BE SQUEEZED OUT IN FAR NORTHERN
IOWA...HOWEVER THIS SYSTEM WILL MAINLY PRODUCE CLOUDS ACROSS THE
STATE.

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 333 AM CST THU FEB 4 2016

QUIET CONDITIONS ARE EXPECTED TONIGHT WITH SURFACE RIDGE
MOVING INTO THE STATE. THE NEXT SHORTWAVE WILL APPROACH THE STATE
ON FRIDAY WITH INCREASING ISENTROPIC LIFT DURING THE MORNING. BEST
THREAT OF DEEPER SATURATION REMAINS ACROSS THE NORTH AND IS THE
LOCATIONS OF HIGH END CHANCE POPS...MAINLY IN THE AFTERNOON INTO
THE EARLY EVENING. SOME LIGHT SNOW AMOUNTS WILL BE POSSIBLE...BUT
ONCE AGAIN THE BEST FORCING AND PCPN THREAT WILL BE NORTH OF IOWA.
BOTH THE SYSTEM TODAY AND ON FRIDAY ORIGINATED OVER THE
PACIFIC...THEREFORE NO COLD BLAST WILL OCCUR ON THE BACKSIDE OF
THESE SYSTEMS. SATURDAY WILL BE A RELATIVELY QUIET DAY AS WARM
ADVECTION INTENSIFIES WITH APPROACH OF THERMAL RIDGE LOCATED IN
THE PLAINS. TEMPERATURES WILL STAY AT OR ABOVE NORMAL DURING THE
WEEKEND PRIOR TO THE ARCTIC AIR POISED TO DROP INTO THE REGION
EARLY NEXT WEEK.

WILL SEE THE PATTERN AMPLIFY INTO MONDAY WITH STRONG SHORTWAVE
DROPPING SOUTHEAST THROUGH THE MIDWEST. THIS WILL DEEPEN THE
EASTERN TROF WITH ARCTIC AIR SPILLING SOUTH INTO THE STATE. THE
AIRMASS WILL ARRIVE LATE SUNDAY WITH STRONG COLD ADVECTION
PERSISTING INTO MONDAY. THERE IS SOME CONCERN FROM SUNDAY NIGHT
INTO MONDAY AS STRONG WINDS ARE EXPECTED DURING THIS TIME.
FORECAST SOUNDINGS SHOW A 1-1.5KM MIXED LAYER DEVELOPING ACROSS
MUCH OF IOWA ON MONDAY WITH 40-50KTS AT THE TOP OF THE LAYER. THIS
WILL LIKELY PRODUCE GUSTS OF OVER 40 MPH LATE SUNDAY NIGHT INTO
MONDAY INITIALLY ACROSS NORTHERN IOWA BUT SPREADING SOUTHWARD ON
MONDAY. IN ADDITION...A GOOD PORTION OF THE LOW LEVELS DROP INTO
THE DENDRITIC GROWTH ZONE WITH SCATTERED SNOW SHOWERS EXPECTED
DURING THE DAY. IT IS LIKELY BLOWING SNOW AND REDUCED VISIBILITIES
WILL OCCUR DURING THE DAY WITH VERY UNPLEASANT CONDITIONS. THE
COLD AIR WILL LAST THROUGH AT LEAST MID WEEK WITH SOME GRADUAL
MODERATION INTO THE LATER HALF OF THE WEEK.

&&

.AVIATION...04/18Z
ISSUED AT 1142 AM CST THU FEB 4 2016

SCATTERED FLURRIES ARE EXPECTED ACROSS NORTHERN IOWA THIS
AFTERNOON...BUT LITTLE AVIATION IMPACTS ARE EXPECTED ASIDE FROM
POCKETS OF MVFR CIGS. CURRENT SOUTHWEST WIND WILL VEER TO THE
NORTHWEST THIS AFTERNOON AND EVENING AS A FRONT PASSES
THROUGH...BACKING TO THE SOUTH AGAIN TOMORROW MORNING.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...SKOW
SHORT TERM...COGIL
LONG TERM...COGIL
AVIATION...SKOW



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