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000
FXUS63 KARX 110853
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
353 AM CDT TUE MAR 11 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT TUE MAR 11 2014

AT 3 AM...A WARM FRONT EXTENDED FROM OMAHA NEBRASKA SOUTHEAST INTO
MISSOURI...AND A COLD FRONT WAS LOCATED OVER CENTRAL MINNESOTA AND
NORTHERN WISCONSIN. THE 11.00Z MODELS ARE IN GOOD AGREEMENT THAT
THE COLD FRONT WILL MOVE SOUTH TO THE INTERSTATE 90 CORRIDOR BY
NOON AND THEN MOVE THROUGH NORTHEAST IOWA AND SOUTHWEST WISCONSIN
THIS AFTERNOON. RAIN IS CURRENTLY FALLING ALONG THE 700 TO 600 MB
FRONTOGENESIS. THIS FRONTOGENETIC BAND BECOMES DEEPER /EXTENDING
FROM 900 TO 600 MB AS IT MOVES SOUTH TOWARD INTERSTATE 90 CORRIDOR
THIS MORNING...AND THEN MOVES SOUTH INTO NORTHEAST IOWA AND
SOUTHWEST WISCONSIN THIS AFTERNOON. BOTH THE NMM...ARW...AND RAP
HAVE A FAIRLY GOOD HANDLE ON THIS PRECIPITATION...SO USED THEM
NARROW THE BAND OF PRECIPITATION MOVING THROUGH THE AREA AND ALSO
TIME ITS OCCURRENCE BETTER. AS WITH THE PAST COUPLE OF DAYS...THE
PRECIPITATION TYPE IS GOING TO BE AN ISSUE. THIS COMPLICATED BY
THE MID 30 DEW POINTS IN THE AREAS WHICH ARE CURRENTLY SEEING
RAIN. THE MODELS ARE ABOUT 3 TO 5F TOO DRY WITH THESE DEW POINTS.
THE DEW POINTS HAVE ACTUALLY ROSE A COUPLE OF DEGREES ONCE THE
RAIN STARTS WHICH MAKE ONE WONDER IF THE MODELS ARE EITHER NOT
HANDLING THE DRY AIR ALOFT THAT WELL OR THE RATES ARE NOT HIGH
ENOUGH TO INCREASE THE EVAPORATIVE COOLING CAUSING THEM TO LOWER.
LOOKED FOR SOME AMDAR SOUNDINGS...BUT DID NOT SEE ANY THAT HAD A
DEW POINT TRACE IN THEM...SO MAY HAVE TO WAIT UNTIL THE 12Z DATA
COMES IN TO EVALUATE THIS. ANOTHER THING THAT CONTINUE TO SHOW UP
IN THE MODELS THAT THEY ARE SLOWER AT COOLING THE NOSE OF THE
WARM AIR ALOFT. STILL EXPECT THAT THE COLUMN WILL EVENTUALLY COOL
ENOUGH FOR A CHANGE OVER FROM RAIN TO A WINTRY MIX OF
RAIN...SLEET...AND SNOW...AND THEN EVENTUALLY TRANSITION OVER TO
ALL SNOW. THIS WINTRY MIX ALONG WITH WARM ROADS /MID AND UPPER
30S/...ABOVE FREEZING TEMPERATURES...AND PRECIPITATION DURATION
GREATLY COMPLICATES THE SNOW FORECAST. IF WE GET PRECIPITATION
RATES HIGH ENOUGH LIKE THE ARW AND NMM SUGGEST...THERE COULD BE A
QUICK SLUSHY 1 TO 2 INCHES OF SNOW ACROSS PARTS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. ELSEWHERE SNOW TOTALS LOOK TO BE
LESS THAN AN INCH.

FOR THIS EVENING...A WINTRY MIX OF RAIN...SLEET...AND SNOW WILL
CHANGE OVER TO ALL SNOW ACROSS NORTHEAST IOWA AND SOUTHWEST
WISCONSIN. UP TO A HALF INCH OF SNOW IS EXPECTED DURING THE
EVENING.

TOWARD MORNING...AN INVERTED TROUGH AND UPPER LEVEL SHORT WAVE
TROUGH WILL MOVE THROUGH THE REGION. THE MODEL CONTINUE TO SUGGEST
THAT THE LOW LEVEL LAPSE RATES WILL STEEP ENOUGH AND THERE WILL BE
ENOUGH OMEGA ALOFT FOR SOME LIGHT SNOW. AMOUNTS LOOK TO BE VERY
LIGHT LESS THAN A HALF INCH...SO KEPT A 20 PERCENT CHANCE FOR NOW.
HOWEVER IF THIS SIGNAL AND LOCATION BECOMES A BIT MORE
CONSISTENT...MAY HAVE TO INCREASE THESE SNOW CHANCES MORE. STRONG
COLD AIR ADVECTION IN THE WAKE OF THIS WAVE WILL RESULT IN THE
HIGH TEMPERATURE FOR WEDNESDAY TO OCCUR BETWEEN MIDNIGHT AND 4 AM.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 350 AM CDT TUE MAR 11 2014

ON WEDNESDAY...SOME LINGERING LIGHT SNOW MAY CONTINUE ACROSS THE
AREA DURING THE MORNING AS THE NORTHERN STREAM SHORT WAVE AND
INVERTED SURFACE TROUGH EXITS THE REGION. STRONG COLD AIR
ADVECTION IN THE WAKE OF THESE TWO SYSTEMS WILL KEEP DAY TIME
TEMPERATURES IN THE TEENS AND LOWER 20S.

ON WEDNESDAY NIGHT AND THURSDAY...STRONG WARM AIR ADVECTION WILL
DEVELOP AHEAD OF AN APPROACHING SHORT WAVE IN THE NORTHERN STREAM.
THIS WILL RESULT IN A WARM FRONT SLIDING EAST ACROSS THE AREA. DUE
TO THIS...WENT WITH A NON-DIURNAL TEMPERATURE CURVE LATE ON
WEDNESDAY NIGHT ACROSS NORTHEAST IOWA AND SOUTHEAST MINNESOTA. THE
280 TO 300K CONDENSATION DEFICITS DECREASE ENOUGH NORTH OF
INTERSTATE 94 THAT THERE MAY BE SOME LIGHT SNOW ASSOCIATED WITH
THIS FRONT. SNOW AMOUNTS LOOK TO BE LESS THAN A HALF INCH.

ON FRIDAY...ANOTHER STRONG CANADIAN COLD FRONT MOVES THROUGH THE
REGION. WITH DRY AIR BEING ADVECTED FROM THE PLAINS AHEAD OF THIS
FRONT...IT STILL LOOKS LIKE THAT THIS FRONT WILL MOVE THROUGH THE
REGION. IF PRECIPITATION DOES HAPPEN TO DEVELOP...IT LOOKS TO BE
NORTH AND EAST OF INTERSTATE 94.

FOR THE WEEKEND...THE MODELS CONTINUE TO SUGGEST THAT MUCH COLDER
925 AND 850 MB TEMPERATURES WILL MOVE INTO THE REGION. THE 850 MB
TEMPERATURES FOR MUCH OF THE WEEKEND ARE IN -8 TO -14C RANGE. WITH
THESE TEMPERATURE...THINKING THAT OUR FORECAST HIGHS AND LOWS ARE
PROBABLY TOO HIGH. THOUGHT ABOUT LOWERING THEM SOME MORE...BUT
WITH THE MODELS STRUGGLING ON THE WESTERN EXTENT OF THIS COLD AIR
DECIDED TO WAIT ANOTHER DAY BEFORE LOWERING THEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1100 PM CDT MON MAR 10 2014

BAND OF PCPN CONTINUES TO DEVELOP WEST-EAST ACROSS THE NORTHERN
PLAINS LATE THIS EVENING...IN A REGION OF FRONTOGENETIC FORCING.
MESO MODEL TRENDS CONTINUE TO SUGGEST THE PCPN WILL MOVE IN A BIT
FARTHER NORTH THAN PREVIOUS FORECASTS...AND HAVE NUDGED THE FORECAST
THIS WAY. THIS DELAYS PCPN ONSET AT KRST/KLSE BY AN HOUR OR TWO.
BUFKIT SOUNDINGS POINT TO A LOW LEVEL WARM/DRY LAYER THAT WILL MAKE
-RA/-RASN MORE LIKELY INITIALLY...WITH QUICK COOLING/SATURATION
CHANGING PTYPE OVER TO -SN WITHIN 3 HOURS OR SO. VSBYS WILL DROP
FROM MVFR TO IFR WITH THE CHANGE OVER. STRONG ENOUGH FORCING THAT A
NARROW BAND OF 1/2SM SN WOULD BE POSSIBLE. MODEL TRENDS SUGGEST THE
BAND OF PCPN WILL SINK SOUTH OF KRST/KLSE BY 00Z...AND SHOULD BE
BREAKING BACK INTO VFR SHORTLY AFTER IT DOES. LOW CLOUDS COULD
QUICKLY RETURN OVERNIGHT TUE AS A SHORTWAVE TROUGH SCOOTS ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY. CONFIDENCE NOT HIGH IN THIS
POTENTIAL AT THIS MOMENT. ANTICIPATE THERE WILL BE REFINEMENTS TO
TIMING/EXITING OF THE PCPN AS TRENDS BECOME CLEARER.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION.....RIECK