622 
FXUS63 KMPX 071202
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
602 AM CST THU FEB 7 2013

.UPDATED FOR 12Z AVIATION DISCUSSION...

&&

.DISCUSSION...
/ISSUED AT 443 AM CST THU FEB 07 2013/
OVERVIEW...REDUCED WHAT POPS WE HAD IN THE FORECAST TODAY FOR
EASTERN MN AND WESTERN WI. THE BIG STORY IS OBVIOUSLY THE WINTER
STORM EXPECTED THIS WEEKEND. THE LATEST MODEL GUIDANCE KEEPS THE
HEAVIEST SNOW IN FAR WESTERN PORTIONS OF THE FORECAST AREA AND
BRINGS A MIX OF SNOW/SLEET/RAIN ELSEWHERE. UNLESS SOMETHING
CHANGES...THERE WOULDN'T BE MUCH SNOW IN WI AND SOUTHERN MN.

07.09Z MSAS SHOWS THE AXIS OF THE INVERTED TROUGH EXTENDING FROM
WESTERN WI DOWN THROUGH IA. THE WARM FRONT STRETCHES FROM JUST
SOUTH OF EAU CLAIRE DOWN THROUGH ALBERT LEA AND INTO NORTH CENTRAL
IA. THE 850 MB FLOW IS ALMOST DUE WESTERLY AND HAS DECREASED OVER
THE LAST 6 HOURS...THUS THE REASON FOR STRATUS CLOUDS BUT NOT MUCH
ELSE. THERE IS CERTAINLY VERY LITTLE TO NO DRIZZLE BEING REPORTED
AND EVEN THE WORST OF THE FOG IS PATCHY AND CONFINED TO NORTHERN
IA AND FAR SOUTHERN MN. DON'T SEE THE NEED FOR LIKELY POPS IN
WESTERN WI TODAY...AND EVEN CHANCE POPS ARE A STRETCH. THINK THE
MODELS ARE HANGING BACK THE LIGHT QPF WAY TOO FAR TO THE WEST. THE
850 MB WINDS ARE WEAK AND NORTHERLY AFTER 12Z. STILL HAVE THE
SHORTWAVE COMING THOUGH TODAY...BUT THE SURFACE LOW
INTENSIFICATION IS JUST TOO FAR TO THE SOUTHEAST TO HAVE ANY
EFFECT ON OUR SENSIBLE WEATHER. IT WILL HOWEVER MAKE FOR AN ACTIVE
24 HOURS IN SOUTHEAST WI AND MICHIGAN WITH THE SLOWER TREND. 

HIGH PRESSURE WILL BUILD INTO THE AREA LATE TONIGHT INTO FRIDAY 
MORNING WITH A STRONG TROUGH DIVING INTO THE SOUTHWEST CONUS. THIS
IS THE SYSTEM EXPECTED TO IMPACT THE FORECAST AREA SATURDAY NIGHT
THROUGH MONDAY. THE HIGH WILL SLIDE EAST OF THE REGION ON SATURDAY
AS THE TROUGH EJECTS OUT OF THE ROCKIES INTO THE CENTRAL PLAINS.
THE TROUGH IS EXPECTED TO CLOSE INTO AN UPPER LOW OVER THE CENTRAL
PLAINS SATURDAY EVENING AND LIFT INTO THE UPPER MISSISSIPPI RIVER
VALLEY REGION LATE SATURDAY NIGHT INTO SUNDAY. STRONG WARM AIR
ADVECTION WILL INITIATE PRECIP SATURDAY SOUTH OF THE AREA AND
SPREAD NORTHWARD DURING THE NIGHT. PRECIPITATION IS EXPECTED TO
START OUT AS A SNOW/SLEET MIX SWITCHING OVER TO FREEZING RAIN THEN
EVENTUALLY OVER TO RAIN LATE IN THE NIGHT AS WARM AIR SURGES IN
ACROSS SOUTHERN MN AND PORTIONS OF WEST CENTRAL WI. SURFACE
TEMPERATURES SHOULD BE COLD ENOUGH THAT THE RAIN WILL FREEZE UPON
CONTACT EVEN THOUGH AIR TEMPERATURES ARE WARMING ABOVE FREEZING.

OVERALL...OUR CHANCES FOR PRECIP SHOULD NOT BE IN QUESTION ON
SUNDAY...WE HAVE 90% IN THE FORECAST NOW AND EVEN IF WE GET THE
DRY SLOT IN HERE SUNDAY EVENING...THE WARM AIR ADVECTION WING OF
THIS SYSTEM WILL BE LONG AND STRONG AND WE COULD JUST AS EASY GO
100% POPS DUE TO THIS. THE P-TYPE IS MESS THIS FAR OUT. THE ECMWF IS 
THE COLDEST /WHEN COMPARED TO NAM AND GFS/ AND THE LATEST NCEP FIM 
MODEL IS EVEN FARTHER EAST WITH THE LOW TRACK WHEN COMPARED TO THE 
GFS AND THE LAST FRAME OF THE NAM AT 84 HOURS. THE NAM IS VERY FAR 
WEST AND WOULD SUGGEST A LOT OF RAIN HERE. THE 07.00/06Z GFS IS 
ABOUT 10 MB LOWER WITH THE CENTRAL PRESSURE WHEN COMPARED TO THE 
ECMWF. WITH A SYSTEM THIS STRONG...HAVE TO BE CONCERNED ABOUT 
DYNAMIC COOLING AND A QUICKER CHANGE OVER TO SNOW...BUT THE TRACK 
WOULD STILL HAVE TO FOLLOW A BLEND OF THE ECMWF/FIM /NOT A BAD BET A 
THIS POINT/...FOR THERE TO BE A BIG CONCERN ABOUT HEAVY SNOW IN 
EASTERN MN AND WI. THE TROWL FEATURE AND STRONG MID LEVEL 
FRONTOGENESIS JUST CLIPS OUR FAR NORTHWEST CWA...SO INCLUDED 
MODERATE TO HEAVY UP NEAR ALEXANDRIA /WITH DOUBLE DIGIT SNOW 
AMOUNTS/...BUT MOST OF THIS WOULD FALL OUTSIDE OF THE CWA AT THIS 
POINT. WE HAVE A MIX ELSEWHERE. WE'LL WAIT AND SEE. TOUGH TO GO WITH 
THE MORE EASTERLY/COOLER SOLUTION WITH ECMWF STILL VERY SLOWLY 
DRIFTING WESTWARD.

&&

.AVIATION.../12Z TAF ISSUANCE/ 
THE INVERTED SURFACE TROUGH TO THE SOUTHEAST WILL GRADUALLY SHIFT
SOUTHEASTWARD TODAY...CAUSING THE WINDS TO REMAIN MAINLY NORTHERLY
TODAY. FORECAST MODELS SHOW LOW LEVEL MOISTURE HANGING AROUND MOST
OF THE DAY...SO HAVE KEPT THE MVFR/IFR CIGS AROUND THROUGH
TONIGHT. CLOUDS SHOULD GRADUALLY BEGIN TO BREAK UP FRIDAY MORNING. 

KMSP...
IFR CIGS TO THE NORTH SHOULD MOVE OVER KMSP THIS MORNING BEFORE
LIFTING TO MVFR THIS AFTERNOON. NOT ANTICIPATING CIGS RISING ABOVE
1700FT BEFORE LATE THIS EVENING. NORTHERLY WINDS WILL GRADUALLY
DIMINISH TONIGHT...AND BECOME EASTERLY ON FRIDAY.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS SE AT 5-10KTS.
SAT...VFR/MVFR WITH -SN POSSIBLE LATE. WINDS SSE AT 10G15KTS.
SUN...MVFR/IFR WITH SN/RA/FZRA. SIGNIFICANT IMPACTS POSSIBLE.
WINDS ESE AT 15G50KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

CLF/JRB