Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 150941
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
441 AM CDT TUE APR 15 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE APR 15 2014

JUST AS THE TROUGH OVERHEAD PIVOTS AND SLOWLY SLIDES EAST
TODAY...ANOTHER POTENT SHORTWAVE WILL MOVE FROM ITS CURRENT LOCATION
IN THE PACIFIC NORTHWEST TO THE NORTHERN ROCKIES AND NORTHERN HIGH
PLAINS TONIGHT. THIS WILL SET UP OUR PRECIP EVENT FOR WEDNESDAY AND
WEDNESDAY NIGHT. THIS MORNING`S WATER VAPOR ALREADY SHOWS GOOD
DRYING ON THE BACK SIDE OF THE WAVE AND 120DM 12-HR 500MB HEIGHTS
FALLS ACROSS OREGON. THE COLD POCKET OVERHEAD LOCALLY REMAINS IN
PLACE THROUGH AROUND 18Z BEFORE WARM ADVECTION KICKS IN LATE THIS
AFTERNOON AND CONTINUES THROUGH THE NIGHT. THE LLJ TONIGHT IS QUITE
STRONG. AT 12Z TOMORROW MORNING...THE ECMWF HAS 50KTS AT 850MB DOWN
NEAR THE MN/IA BORDER - THE GFS AND NAM HAVE 60KTS AND 65KTS
RESPECTIVELY. SO...THAT WILL CERTAINLY SET UP A NICE WARM SECTOR AND
BAROCLINIC ZONE TOMORROW MORNING. THE RESULTING FGEN WILL BEGIN
GENERATING SNOW IN THE NORTHEAST QUADRANT OF THE SURFACE CYCLONE
BETWEEN 09Z-12Z. THE REST OF THE PRECIP ACROSS THE PLAINS WILL BE ON
THE BACK SIDE OF THE LOW. THE EARLY ECHOES THAT FORM TOMORROW
EVENING IN SD/ND WILL POINT THE WAY TO WHERE THE HEAVIEST SNOW WILL
FALL. AT THIS TIME...THE NAM/GFS/ECMWF ARE ALL IN PRETTY GOOD
AGREEMENT WITH THE INITIAL LOCATION OF PRECIP...BUT THERE ARE SOME
TIMING ISSUES. BY SUNRISE WEDNESDAY MORNING...THE P-TYPE IN CENTRAL
MN SHOULD BE ALMOST COMPLETELY SNOW. THERE COULD ALREADY BE 1-2" ON
THE GROUND IN CENTRAL MN BEFORE THE MORNING COMMUTE.



.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE APR 15 2014

PICKING UP WEDNESDAY MORNING AS A LEADING BAND OF WARM ADVECTION SNOW
WILL BE SETUP ACROSS NORTH CENTRAL MINNESOTA...AND WILL BE MAINLY
AFFECTING THE NORTHERN TIER OF COUNTIES IN THE MPX FA. ADDITIONAL
PRECIPITATION WILL DEVELOP TO THE SOUTHWEST OF THIS BAND AND
EVENTUALLY MERGE WITH THE INITIAL BAND AS THE SURFACE LOW ENTERS
SOUTHERN MINNESOTA DURING THE DAY. THE MAIN CONCERNS WITH THIS
FORECAST PACKAGE ARE THE TIMING DIFFERENCES BETWEEN THE FAST
GFS AND SLOW ECMWF. THE NAM SPLITS THESE SOLUTIONS IN TERMS OF
TIMING...SO STILL DETAILS TO BE SORTED OUT IN THAT REGARD. DESPITE
THESE TIMING DIFFERENCES...THERE IS DECENT AGREEMENT IN
PRECIPITATION AMOUNTS...AND THE NORTHERN THIRD OF THE CWA IS STILL
EXPECTED TO RECEIVE THE HEAVIEST PRECIPITATION. WENT AHEAD AND
UPPED POPS TO CATEGORICAL ACROSS THE ABOUT THE NORTHERN HALF OF
THE CWA DURING THE DAY. THE HEAVIES SNOW WILL FALL DURING THE DAY
AS THE FORCING COMES TOGETHER. A WELL DEFINED PV ANOMALY WILL PUSH
EAST ACROSS SOUTHERN MINNESOTA...WHILE STRONG 700H OMEGA IS
MAXIMIZED ON ITS NORTHERN PERIPHERY (BETWEEN ST. CLOUD AND
BRAINERD) OFF THE NAM WHICH LINES UP WELL WITH THE GREATEST FN
VECTOR CONVERGENCE...AND ON THE SOUTHERN EDGE OF THE STRONGEST
FRONTOGENESIS. DIFFERENTIAL DIVERGENCE FROM JET LEVEL DOWN TO THE
LOW LEVELS INDICATES THIS AREA ALONG THE SOUTHERN PERIPHERY OF THE
STRONGEST LIFT AS WELL. CROSS SECTIONS OFF THE NAM INDICATE
NEGATIVE EPV ALOFT AND THE AGEOSTROPHIC CIRCULATION EXEMPLIFIED
THE DEEP LIFT ACROSS THIS SAME AREA. PRECIPITATION TYPE WILL
OBVIOUSLY PLAY A LARGE ROLE ON SNOW ACCUMULATIONS AND IMPACT.
LITTLE CHANGE WAS NEEDED TO THE PRECIPITATION TYPE FORECAST AS THE
TIMING DIFFERENCES AMONGST THE MODELS STILL LENDS UNCERTAINTY TO
THE RAIN/SNOW LINE. BUT OVERALL...NORTH OF ST. CLOUD STILL LOOKS
TO BE PRIMARILY SNOW...WITH THE POSSIBILITY OF A LITTLE RAIN
MIXING IN WEDNESDAY AFTERNOON...WHILE THE TWIN CITIES METRO WILL
SEE PRIMARILY RAIN DURING THE DAY BEFORE SWITCHING OVER TO SOME
LIGHT SNOW AT THE TAIL END OF THE EVENT. THE PRECIPITATION WILL
COME TO AN END WEDNESDAY NIGHT THROUGH THURSDAY MORNING FROM WEST
TO EAST. CONFIDENCE TO ISSUE A WINTER STORM WARNING WAS NOT
ACHIEVED WITH THE LATEST MODEL RUNS...SO DECIDED TO CONTINUE THE
WINTER STORM WATCH FOR THE SAME COUNTIES FOR NOW.

CANADIAN HIGH PRESSURE WILL BE ON THE HEELS OF THE STORM...AND
WILL KEEP TEMPERATURES COLDER THAN NORMAL TO FINISH OUT THE WORK
WEEK. BOTH THE GFS AND EC ADVERTISE A WAVE BRINGING RAIN TO THE
REGION SATURDAY NIGHT...BUT THERE WILL BE A GOOD DEAL OF DRY AIR
TO COMBAT...SO DECIDED CHANCE POPS WERE IDEAL FOR NOW. WE`RE STILL
EXPECTING A WARMING TREND THROUGH THE WEEKEND WITH A RETURN TO
MORE SPRING LIKE TEMPERATURES...ESPECIALLY BY MONDAY.



&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1044 PM CDT MON APR 14 2014

VFR OVERNIGHT AND TUESDAY AS HIGH PRESSURE SETTLES IN. NW WINDS
10 KNOTS OR LESS OVERNIGHT BACKING TO THE WSW ON TUESDAY.
CLOUDINESS WILL BE THICKENING AND LOWERING TUESDAY NIGHT AHEAD OF
A DEVELOPING WARM FRONT SOUTH OF THE TAF SITES. SOME LIGHT SNOW IS
POSSIBLE NEAR THE END OF THE TAF PERIOD BUT CONFIDENCE IS NOT
HIGH. INDICATED VCSH FOR NOW. MVFR/IFR CEILINGS DEVELOPING LATE
TUESDAY NIGHT ALONG WITH AREAS OF RAIN/SNOW.

KMSP...VFR THROUGH TUESDAY EVENING. NW WINDS WILL SLOWLY DIMINISH
OVERNIGHT TO AROUND 7 KNOTS AND THEN BACK TO THE SW BY LATE IN
THE DAY ON TUESDAY. WINDS BACKING TO THE ESE TUESDAY EVENING ALONG
WITH SPEEDS INCREASING TO AROUND 10 KNOTS. A SMALL THREAT FOR
LIGHT SNOW TUESDAY NIGHT WITH HIGHER CONFIDENCE TO THE NORTH OF
THE AIRFIELD.

/OUTLOOK FOR KMSP/

WED...MVFR/IFR. RAIN LIKELY. WINDS E 10-15 KTS BECOMING NE.
WED NGT...MVFR/IFR. RAIN CHANGING TO SNOW EARLY. WINDS NNE 10-15 KTS.
THU...VFR. WINDS NNE 10-15 KTS.
FRI...MAINLY VFR. SLGT CHC MVFR CIGS WITH -RA/-SN. WINDS NE 10 KTS.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING
     FOR MNZ042>045-050-052-053.

WI...WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING
     FOR WIZ014>016.

&&

$$

SHORT TERM...CLF
LONG TERM...SPD
AVIATION...RAH






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