Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 161824
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
124 PM CDT WED APR 16 2014

.UPDATE...
ISSUED AT 1104 AM CDT WED APR 16 2014

DEFORMATION ZONE BETWEEN AREAS RECEIVING HEAVY SNOW...POTENTIALLY
1-2 IN/HR RATES...AND THE DRY SLOTTING ARRIVING FROM THE SW IS
BECOMING TIGHTER BUT ALSO SHIFTED SLIGHTLY FURTHER S. WITH STILL
PLENTY OF AVAILABLE MOISTURE AS THE LOWER LEVELS ARE GRADUALLY
BECOMING SATURATED...ACCUMULATING SNOWFALL IS NOW MUCH MORE LIKELY
OVER A TIER OF COUNTIES S OF ORIGINAL THINKING. RAP/RUC GUIDANCE
FALLS IN LINE WELL WITH A NUMBER OF FEATURES...INCLUDING THE
LOCATION/INTENSITY OF THE DRY SLOT...ENHANCED FGEN AND STRONGER
LIFT. PLUS...COLDER AIR BEING MORE RESIDENT DUE TO STRONG ELY FLOW
WITHIN THE PRECIP AND SOME EVAPORATIVE COOLING EFFECTS FURTHER S
HAVE FORCED LOWERING OF THE MAX TEMPS AND HOURLY GRIDDED TEMPS.
ALL IN ALL...THIS MEANS AN OVERALL RAISING OF SNOWFALL
ACCUMULATIONS AND A SOUTHWARD EXPANSION OF THE COUNTIES INCLUDED
IN THE WINTER WEATHER ADVISORY...INCLUDING HENNEPIN AND RAMSEY
COUNTIES. THERE STILL LOOKS TO BE A BREAK IN THE ACTION RIGHT UP
TO THE TWIN CITIES AND WHEN PRECIP WOULD CHANGE OVER TO RAIN FOR
SOUTH-CENTRAL PORTIONS OF THE MPX CWFA. HOWEVER...THIS WINDOW
LOOKS SMALLER /APPROXIMATELY 18Z-00Z/...WITH AN HOUR OR TWO OF
WIGGLE ROOM ON EITHER SIDE WHEN -RASN MAY OCCUR. PRECIP LOOKS TO
CHANGE BACK OVER TO ALL -SN BY ARND 02Z. THE CONCERN BY THEN IS
THAT THE UPPER TROF MAY BECOME MORE NEGATIVELY TILTED WITHIN THE
DEEPER MOISTURE AND COLDER AIR ON THE BACKSIDE OF THIS SYSTEM
WOULD CREATE BANDED HEAVIER SNOWFALL FOR ERN PORTIONS OF THE CWFA.
THIS COULD MEAN ADDITIONAL HEAVIER SNOWS THIS EVENING INTO TNGT.
WILL CONTINUE TO MAKE MODEL EVALUATIONS AND UPDATE THE FCST AS
NEEDED WITH THIS EVOLVING SYSTEM.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT WED APR 16 2014

UPPER TROUGH WAS ENTERING THE WESTERN DAKOTAS THIS MORNING WITH
INCREASING MOISTURE AS EVIDENT VIA WATER VAPOR IMAGERY.  MAIN
CHANGES TO THE SHORT TERM PACKAGE WAS TO SLIGHTLY SLOW THE SYSTEM
DOWN.  HI-RES MODELS AND NAM CAME IN WITH A SLOWER PROGRESSION OF
THIS WAVE.  DUE TO THIS SLOW DOWN...THE DEFORMATION ZONE WILL BE
ORIENTED SLIGHTLY FURTHER BACK TO THE WEST SO SNOW AMOUNTS WERE
INCREASED SOUTHWEST OF ALEXANDRIA.  THE NORTHERN PORTION OF THESE
COUNTIES WILL SEE SIGNIFICANT ACCUMULATION TODAY...SO WENT AHEAD
AND EXPANDED THE WINTER WEATHER ADVISORY SOUTH FROM MADISON
THROUGH WILLMAR AND BUFFALO. IN ADDITION...THE HEAVIEST
PRECIPITATION BAND STILL MATCHES UP WELL WITH THE WARNING
AREA...BUT NORTHEASTERN STEARNS AND NORTHERN BENTON COUNTIES SNOW
AMOUNTS WERE INCREASED GIVEN MORE MOISTURE AND ADDITIONAL QPF
PUSHING THESE AREAS INTO WARNING CRITERIA. THESE TWO COUNTIES HAVE
BEEN UPGRADED TO A WINTER STORM WARNING. FOR THE TWIN CITIES
METRO...LOW LEVEL DRY AIR WILL PUSH WELL NORTH OF THE IOWA BORDER
AND KEEP THE METRO RELATIVELY QUIET THROUGH THE MORNING. BY THE
TIME SATURATION IS ACHIEVED...IT WILL BE WARM ENOUGH FOR PURELY
RAIN TO FALL. WITH THE DEFORMATION ZONE TAKING MORE OF A TILT
TOWARD THE WEST...IT WILL PUSH THROUGH THE METRO THIS
AFTERNOON/EVENING AND CAUSE A CHANGEOVER TO SNOW ONCE SURFACE
TEMPERATURES BEGIN TO COOL. A QUICK BURST OF SNOW FOR THE METRO
COULD IMPACT THE EVENING COMMUTE IN...BUT ROAD SURFACES MAY REMAIN
MOSTLY WET. IN WESTERN WISCONSIN...TEMPERATURES APPEAR SLIGHTLY
WARMER IN THE LOW LEVELS...BUT ENOUGH TO MAKE A DIFFERENCE IN
RAIN/SNOW PLACEMENT. SNOW RATIOS LOOK LOWER THAN PREVIOUSLY IN
THIS AREA...ESPECIALLY GIVEN THE WARMER SURFACE TEMPERATURES THIS
AFTERNOON. SO...SNOW AMOUNTS WERE DECREASED SOMEWHAT...BUT THE
COUNTIES IN THE WARNING STILL LOOK TO SEE SIX OR MORE INCHES OF
SNOW. THE SNOW WONT COME TO AN END IN WESTERN WISCONSIN UNTIL
THURSDAY MORNING GIVEN THE SPEED OF THE SYSTEM SLOWING DOWN.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 415 AM CDT WED APR 16 2014

THE LONG TERM WILL START OFF RATHER QUIET ASIDE FROM A FEW
FLURRIES OR LINGERING LIGHT SNOW ACROSS THE CENTRAL WISCONSIN
COUNTIES EARLY THURSDAY MORNING. BY AFTERNOON...RIDGE OF HIGH
PRESSURE WILL BUILD IN WITH THE AXIS LOCATED ACROSS EASTERN
MINNESOTA AND WESTERN WISCONSIN THURSDAY NIGHT AND EARLY FRIDAY.
SHOULD BE ANOTHER NIGHT OF WELL BELOW AVERAGE TEMPS...ESPECIALLY
IN AREAS WITH SEVERAL INCHES OF SNOW ON THE GROUND. LOWERED TEMPS
A BIT ACROSS CENTRAL MN AND NWRN WI FOR THIS LIKELIHOOD. ON THE
SOUTHWESTERN PERIPHERY OF THE RIDGE...MODELS DISAGREE ON THE
EXISTENCE OF A FAST MOVING SHORT WAVE THAT BRINGS WITH IT A NARROW
SWATH OF PRECIP ACROSS SOUTH DAKOTA AND FAR SOUTHERN MN/NORTHERN
IOWA. GFS AND NAM SEEM MUCH TOO BULLISH ON AMOUNTS CONSIDERING THE
LARGE RIDGE JUST TO THE NORTH AND THE AMOUNT OF DRY AIR
ACCOMPANYING IT. GEM AND ECMWF DON/T ACKNOWLEDGE THIS FEATURE.
FIGURED IT WAS AT LEAST WORTH A SLIGHT CHANCE NEAR THE IOWA
BORDER.

A SYSTEM WILL PROPAGATE ACROSS THE NORTHERN PLAINS AND SOUTHERN
CANADA SATURDAY WITH THE COLD FRONT TRAVERSING THE CWA SATURDAY
NIGHT. MOISTURE RETURN AHEAD OF THIS FRONT APPEARS SUFFICIENT
ENOUGH FOR PRECIP TO ACCOMPANY THE FRONT...BUT NOT ENOUGH TO BRING
MUCH THREAT OF THUNDER.

A PATTERN SHIFT WILL BE UNDERWAY COME EARLY NEXT WEEK. TROUGHINESS
EMERGING ACROSS THE ROCKIES/WEST COAST WILL RESULT IN BUILDING
HEIGHTS TO THE EAST ACROSS THE CENTRAL CONUS. TEMPERATURES WILL
TREND ABOVE AVERAGE LEVELS DURING THIS TIME WITH HIGHS LIKELY
REACHING THE 60S AND 70S ON A NUMBER OF DAYS NEXT WEEK. WILL NEED
TO KEEP AN EYE ON A STORM SYSTEM DEVELOPING MIDWEEK ACROSS THE
WESTERN HIGH PLAINS IN RESPONSE TO THE DIGGING TROUGH. IT MAY
BRING SOME POTENTIAL OF SEVERE WEATHER ACROSS THE NORTHERN PLAINS
AND MISSISSIPPI VALLEY DEPENDING ON ITS EVOLUTION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 106 PM CDT WED APR 16 2014

AXN/STC/RWF CONTINUE TO BE MOST AFFECTED BY MOD/HVY SNOW THIS AFTN
AS THE SWATH OF PRECIPITATION WITHIN AIR COLD ENOUGH TO PRODUCE
SNOW RATHER THAN RAIN LINGERS FROM SWRN MN INTO N-CENTRAL MN.
MSP/RNH/EAU HAVE EMERGED TO HAVE LITTLE-TO-NO PRECIP AT 16/18Z
INITIALIZATION...BUT WITHIN A FEW HOURS TIME THE PRECIPITATION
AREA WILL GRADUALLY SHIFT EWD...BRINGING PRECIP BACK TO THE ERN
TAFS. PRECIP LOOKS TO RETURN AS -RA FOR A FEW HRS BEFORE A BRIEF
TRANSITION TO -RASN BEFORE ALL -SN. THE CONCERN THEN BECOMES
MESOSCALE BANDING OF PRECIP FOR THESE ERN SITES AS THE UPR LEVEL
TROF PIVOTS ALOFT OVER SRN MN THIS EVENING...SETTING THE STAGE FOR
ENHANCED LOCALIZED LIFT WHICH COULD PRODUCE PERIODS OF IFR-WORTHY
HVY SNOW THIS EVENING. HAVE USED TEMPO GROUPS TO ADVERTISED THIS
ATTM. THE PRECIP LOOKS TO BE LARGELY AWAY FROM THE TERMINALS BY
06Z THIS EVE...A LITTLE LATER FOR THE WI SITES. THE OTHER CONCERN
IS THE POTENTIAL FOR LLVL STRATUS OVERNIGHT WITH THE DEEP MOISTURE
WITHIN THE BLYR...BUT AM NOT ENTIRELY SOLD ON THIS IDEA DUE TO THE
STRONG LLVL NW WINDS XPCTD SO ASIDE FROM MVFR CIGS...HAVE LEFT
VSBY AS IMPROVING TO VFR.

KMSP...DEFINITIVE BREAK IN THE PRECIP HAS DEVELOP OVER MSP...
GOING MAINLY S AND E FROM THERE...WHILE PRECIP IS NOT FAR OFF AT
ALL GOING N AND W. AS THE AFTN PROGRESSES...THIS DRY PERIOD WILL
COME TO AN END WITH -RA RETURNING FROM THE W BY MID-AFTN. TEMPS IN
THE MID-30S WILL ALLOW FOR A P-TYPE OF SHOWERY -RA WHEN IT
RESUMES. AS COLDER AIR WRAPS AROUND THE BACKSIDE OF THE LOW PRES
CENTER SHIFTING EWD OVER SRN MN LATE THIS AFTN...PRECIP WILL MIX
WITH AND EVENTUALLY CHANGE BACK OVER TO -SN. SOME MINOR SNOW
ACCUMULATION IS POSSIBLE...ALONG WITH POTENTIAL BANDS OF MOD-HVY
SNOW...DUE TO MESOSCALE EFFECTS BUT ITS POTENTIAL IS ENOUGH TO
CARRY A TEMPO GROUP THIS EVENING. CONDS IMPROVE LATE OVERNIGHT
THRU THE DAY TMRW TO VFR WHILE WINDS TAKE ON A DRIER NW FLOW.

/OUTLOOK FOR KMSP/
THU...MAINLY VFR. SOME MVFR CIGS EARLY. WINDS NNE 10-15 KTS.
FRI...MAINLY VFR. CHC MVFR FRI NIGHT WITH -RA/-SN. WINDS NE 5-10
KTS.
SAT...MAINLY VFR. CHC MVFR WITH -RA/-SN. WINDS E-SE 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 10 PM CDT THIS EVENING FOR MNZ041-
     047-048-054>057-064-065-073.

     WINTER STORM WARNING UNTIL 4 AM CDT THURSDAY FOR MNZ042>045-
     049>053.

     WINTER WEATHER ADVISORY UNTIL 4 AM CDT THURSDAY FOR MNZ058>063-
     066-068.

WI...WINTER STORM WARNING UNTIL 4 AM CDT THURSDAY FOR WIZ014.

     WINTER WEATHER ADVISORY UNTIL 4 AM CDT THURSDAY FOR WIZ023.

     WINTER STORM WARNING UNTIL 7 AM CDT THURSDAY FOR WIZ015-016.

     WINTER WEATHER ADVISORY UNTIL 7 AM CDT THURSDAY FOR WIZ025-027.

&&

$$

UPDATE...JPC
SHORT TERM...SPD
LONG TERM...BORGHOFF
AVIATION...JPC






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