000
FXUS63 KDMX 041802
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1202 PM CST TUE MAR 4 2014

...UPDATED FOR 18Z AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
ISSUED AT 327 AM CST TUE MAR 4 2014

INCREASING CHANCES OF SNOW THIS AFTERNOON AS A QUICK MOVING
SHORTWAVE ENTERS SOUTHERN MINNESOTA AND NORTHERN IOWA BY LATE THIS
AFTERNOON. GOOD THETA-E ADVECTION BETWEEN 850MB TO 700MB ENTERS
NORTHERN IOWA PAST 21Z AND SOUNDINGS FROM EST TO MCW BECOME DEEPLY
SATURATED B/T 21Z TO 00Z TIME FRAME. BOTH THE NAM/GFS HAVE SOME
WEAK FRONTOGENETICAL FORCING IN THE 750-700MB LAYER BY 00Z
WEDNESDAY AND IS PRIMARILY WITHIN THE DENDRITIC LAYER...WHICH
LOOKS TO BE BETWEEN 700-600MB. THIS MATCHES UP WELL WITH THE
DEEPER MOISTURE MOVING ACROSS NORTHERN IOWA LATE THIS AFTERNOON.
SNOW RATIOS SHOULD INCREASE TO AROUND 15:1 BY 22-23Z TIME
FRAME...LEADING TO HALF TO UP TO AN INCH POSSIBLE BY 00Z WEDNESDAY
OVER FAR NORTHERN IOWA.

WITH REGARD TO TEMPERATURES TODAY...WENT GENERALLY ABOVE GUIDANCE
FOR MAX TEMPS TODAY OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST
AREA AS THERE WILL BE SOME WEAK WAA AND LIKELY ENOUGH SUNSHINE
BEFORE THE CLOUD COVER MOVES BACK IN THIS AFTERNOON. FURTHER
NORTH...LEANED TOWARD THE NAM FOR TEMPERATURES.

.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 327 AM CST TUE MAR 4 2014

MAIN CHALLENGE IN THE EARLY PORTION OF THE FORECAST PERIOD WILL BE
THE SHORT WAVE NOW OVER THE PACNW HEADING ESE BY TOMORROW EVENING
AND AFFECTING NORTHERN/CENTRAL IOWA. MODELS IN GENERALLY GOOD
AGREEMENT ON TIMING WITH WARM AIR ADVECTION AND INCREASING
H700/H850 FRONTO FORCING BY 00Z OVER NORTHERN IOWA. THE FORCING
IS TENDING TO WEAKEN WITH TIME AS THE WAVE TRACKS OVER THE
REGION...SO QPF SHOULD REMAIN ON THE LIGHT TO MODERATE SIDE
GENERALLY UNDER A TWO TENTHS OF AN INCH OVER THE NORTH WITH LESSER
AMOUNT SOUTH. GFS TIME CROSS SECTION AT KMCW SHOWS THE BETTER LIFT
BENEATH THE DENDRITIC LAYER THOUGH IT JUST ENTERS THE LOWER
PORTION OF THE LAYER FROM 00Z THROUGH 03Z. TONIGHTS EURO RUN HAS
INCREASED FORCING ACROSS THE NORTH BY LATE TODAY/TONIGHT AND WITH
A BLEND OF SOLUTIONS AN AREA OF 2 TO 3 INCHES OF SNOW SHOULD OCCUR
OVER THE NORTH WITH LIGHTER SNOW TOTALS CENTRAL AND SOUTH OF ABOUT
AN INCH. THE MODELS SUGGEST ANOTHER WEAKENING WAVE TRACKING ACROSS
SOUTHERN NEBRASKA EAST TO NORTHERN MISSOURI FROM 12Z WED THROUGH
00Z THURSDAY AND THIS MAY ADD ANOTHER DUSTING TO THE SOUTH DURING
THE DAY ON WEDNESDAY.

THOUGH MILDER AIR IS THE THEME THIS WEEK...AFTER LOWS IN THE TEENS
TUES NIGHT WED HIGHS WILL BE SOMEWHAT COOLER THAN TUES WITH H850
TEMPS -4C WEST TO -9C NORTHEAST DURING THE AFTERNOON HOURS. THERE
MAY BE SOME SUNSHINE BUT THE RIDGE ISNT AROUND LONG ENOUGH TO
COMPLETELY CLEAR OUT THE REGION.  A MORE SIGNIFICANT PUSH OF MILDER
ADIABATICALLY FORCED AIR FROM THE WESTERN PLAINS WILL MOVE ACROSS
THE REGION WED NIGHT INTO THURSDAY. UNFORTUNATELY A STRONG
INVERSION WILL MASK MUCH OF THE WARMING OVER IOWA...THOUGH SFC
ADVECTION AND AFTERNOON MIXING WILL STILL ALLOW FOR A NICE WARMING
INTO THE 20S NORTHEAST TO THE UPPER 30S TO LOWER 40S SOUTHWEST.
WITH SEVERAL DAYS OF MODERATING TEMPERATURES THE POTENTIAL FOR
STRATUS AND POTENTIAL FOR FOG WILL INCREASE ACROSS THE AREA AS
WELL...MAINLY LATE THURSDAY INTO FRIDAY. MODELS BEGIN TO PART WAYS
FRIDAY AS GFS/NAM LIGHT UP A COOL FRONT WITH LIGHT PRECIPITATION
WHILE THE EURO/GEM ARE TOO DRY TO INITIATE ANY QPF UNTIL SATURDAY
AS THE FRONT DROPS INTO NORTHERN MISSOURI. FOR NOW WILL LEAVE
SLIGHT CHANCES FOR R/S MIX ON FRIDAY THOUGH CONSENSUS WOULD FAVOR
LATE FRIDAY NIGHT/SATURDAY ACROSS THE SOUTH. TEMPS WILL RECOVER
SUNDAY AND MONDAY WITH A NICE PUSH OF MILD AIR INTO THE STATE FROM
THE WEST. HIGHS SHOULD WARM INTO THE 40S SUNDAY AND THE 40S TO
LOWER 50S BY MONDAY. FROM LATE WEEK INTO THE WEEKEND FOG OR SOME
STRATUS MAY BECOME MORE OF A CONCERN AND WILL NEED TO MONITOR
THROUGH THE PERIOD.

&&

.AVIATION...04/18Z
ISSUED AT 1145 AM CST TUE MAR 4 2014

SNOW TO IMPACT ALL TAF SITES DURING FORECAST PERIOD. HIGH
CONFIDENCE THAT KMCW AND KALO WILL SEE BIGGEST IMPACTS AS MVFR AND
IFR CIGS/VSBYS TO DEVELOP PRIMARILY AFTER 03Z WED. INTENSITY SNOW
BIGGEST FACTOR...AND WILL BE MONITORING POTENTIAL FOR LOWER VSBYS
AT KMCW...KALO...AND KFOD. BY 09Z...HEAVIEST SNOW TO START
PUSHING EASTWARD OF KMCW...AND BY 12Z HEAVIEST SNOW TO BE EAST OF
KALO. WATCHING FOR POTENTIAL OF LIGHT BAND OF SNOW TO PROPAGATE SE
FROM KFOD THROUGH KOTM FROM 06Z TO AROUND 14Z. WITH NERLY WINDS
LESS THAN 10KTS...KEPT VSBY AROUND 6SM DURING BAND OF LIGHT SNOW.

&&

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

$$

SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...KOTENBERG