Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 241219
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
719 AM CDT TUE MAR 24 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT TUE MAR 24 2015

TOUGH FORECAST AHEAD FOR THIS AFTERNOON AND TONIGHT ON PTYPE AND
RESULTING PRECIPITATION AMOUNTS. THERE WAS QUITE THE DIFFERENCE
OUT THE GATE WITH THE 00Z RUNS BETWEEN THE NAM/GFS VERSUS THE
ECMWF/CANADIAN ON THE LAYOUT OF THE PRECIPITATION PATTERN
DEVELOPING LATER THIS AFTERNOON AND SPREADING ACROSS THE FA
TONIGHT. THE ECMWF AND CANADIAN ARE MUCH FARTHER SOUTH ON THE QPF
AXIS WITH A QUARTER INCH TONIGHT BARELY ACROSS THE SOUTHEAST PART
OF MN WHILE THE NAM/GFS HAVE THE QUARTER INCH INTO THE TWIN
CITIES. A CHECK ON RAP RUNS OVERNIGHT INDICATED A QPF PATTERN
DEVELOPING LIKE WHAT THE ECMWF AND CANADIAN ARE SHOWING. WE
BELIEVE PART OF REASON FOR THE DIFFERENCE IS THE CONVECTION
ONGOING TO OUR SOUTH THIS MORNING WITH STRONGER ACTIVITY PROGGED
FOR THIS AFTERNOON. THE NOSE OF THE 925-850MB MOISTURE TRANSPORT
WITH THE ECMWF JUST REACHES UP INTO NE IA THIS EVENING AND THEN
PASSES ACROSS SOUTHERN WI THIS EVENING. OUR INTERNAL MPX ARW-WRF
IS ALSO SHOWING THE QPF AXIS FURTHER SOUTH AS WELL. PTYPE THIS
AFTERNOON IS IN QUESTION WITH THE HRRR AND RAP SOUNDINGS
INDICATING SURFACE DEW POINTS RISING INTO THE LOWER AND MIDDLE 30S
ACROSS SOUTHERN MN WITH ALL RAIN INDICATED. THEY MAY BE TOO WARM
AS OUR MPX WRF SHOWS A CHANGE OVER TO SNOW ACROSS SOUTH CENTRAL MN
IN THE 21Z-24Z TIME FRAME ALONG WITH SOME FREEZING RAIN. HEADING
THROUGH THE EVENING...A DEEP MID LEVEL WAVE WILL PASS ACROSS IA/MO
WITH A DEFORMATION ZONE FROM NEAR KAEL TO KEAU. THIS IS THE ZONE
FOR 2 TO 4 INCHES OF SNOW ACCUMULATION TONIGHT WITH MUCH OF IT
OCCURRING BEFORE 06Z. SNOW AMOUNTS ARE LESS TO THE NORTHWEST WITH
AN INCH OR TWO IN THE TWIN CITIES WITH AROUND AN INCH AT ST.
CLOUD. BASED ON PTYPE ISSUES THIS AFTERNOON ALONG WITH THE SNOW
TONIGHT COUPLED WITH SOME MIXED SLEET AND FREEZING RAIN...WE
ISSUED A WINTER WEATHER ADVISORY FOR SOUTH CENTRAL MN BEGINNING
LATE THIS AFTERNOON WITH THE ADVISORY SPREADING NORTHEAST ACROSS
MUCH OF WEST CENTRAL WI FOR TONIGHT.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM CDT TUE MAR 24 2015

THE EXTENDED IS ACTUALLY LOOKING FAIRLY QUIET WITH THE MAIN
HAPPENINGS BEING THAT OF A PATTERN SHIFT...WITH A HIGHLY AMPLIFIED
PATTERN THIS WORK WEEK FLATTENING OUT AND BECOMING MORE ZONAL THIS
WEEKEND INTO NEXT WEEK. THE RESULT...TEMPS WILL REMAIN WELL BELOW
NORMAL THE REST OF THIS WORK WEEK...BUT BY THE WEEKEND...THEY WILL
REBOUND BACK TO NEAR OR EVEN A LITTLE ABOVE NORMAL.

THE LONG TERM WILL START WITH TONIGHTS TROUBLE MAKER PUSHING OUT OF
THE MPX AREA WEDNESDAY MORNING. GUIDANCE HAS CONTINUED TO PUSH WRAP
AROUND PRECIP WED/WED NIGHT FARTHER NORTH. IT IS LOOKING MORE AND
MORE LIKELY THAT THE MPX AREA WILL REMAIN DRY THIS PERIOD AS THE
WRAP AROUND MOISTURE STAYS CLOSER TO THE NRN SFC LOW THAT WILL BE
TRACKING ACROSS THE ARROWHEAD. HAVE CONTINUED THE TREND OF CUTTING
BACK POPS ON WEDNESDAY...WITH WED/WED NIGHT NOW BASICALLY DRY SOUTH
OF I-94. WHAT LOOKS MORE CERTAIN FOR WEDNESDAY ARE BREEZY
CONDITIONS. THE NAM SHOWS 3 HR PRESSURE RISES OF ABOUT 6 MB
FOLLOWING THE SFC LOW ACROSS THE ARROWHEAD...WITH 3 MB/3 HR RISES
ALL THE WAY DOWN INTO CENTRAL MN. IN ADDITION...BUFR SOUNDINGS UP AT
AXN SHOW MID CHANNEL MIX DOWN WINDS NEAR 35 KTS WITH TOP OF THE
CHANNEL WINDS AROUND 40 KTS. AS A RESULT...GAVE FORECAST WIND SPEEDS
A PRETTY GOOD BOOST FOR WEDNESDAY...WITH BORDERLINE WIND ADVY WINDS
NOW IN PLACE ACROSS WEST CENTRAL MN.

FOR THURSDAY AND FRIDAY...THE H5 FLOW BECOMES ALMOST NORTHERLY...
WHICH WILL ALLOW A 1035MB HIGH TO DROP DOWN OUT OF CANADA. WITH H85
TEMPS DOWN BETWEEN -6 TO -10C...WE WILL SEE HIGHS REMAIN IN THE 30S
BOTH DAYS...WITH SOME LOWS IN THE SINGLE DIGITS NOT OUT OF THE
QUESTION FRIDAY MORNING AS THE SFC HIGH SETTLES OVER MN AND OUR SNOW
COVER. THE ONE CHANGE SEEN WITH THE GUIDANCE THIS PERIOD IS THE
GEM/GFS/ECMWF ARE ALL SHOWING A QUICK HIT OF LIGHT PRECIP WORKING
ACROSS THE ERN DAKOTAS AND FAR WRN MN FRI/FRI NIGHT AS SHORT WAVE
ENERGY DROPPING DOWN IN THE NRLY FLOW WORKS WITH THE BAROCLINIC ZONE
ON THE BACKSIDE OF THE HIGH TO PRODUCE SOME LIGHT QPF. STILL HAVE A
DRY FORECAST OUT THAT DIRECTION...BUT IF THIS TREND CONTINUES...WE
MAY NEED TO START ADDING SOME SNOW CHANCES TO THE WEST FOR FRIDAY
EVENING.

THIS WEEKEND...AS THE UPPER FLOW BECOMES LESS AMPLIFIED...WE WILL
SEE A DEEP SFC LOW DROP OUT OF THE CANADIAN ARCTIC AND MOVE TOWARD
NW QUEBEC. WE WILL BE WELL WITHIN THE WARM SECTOR OF THIS SYSTEM...
THOUGH SAID WARM SECTOR IS STILL SCHEDULED TO COME THROUGH IN THE
DEAD OF NIGHT SATURDAY NIGHT. THE GEM/GFS BOTH HAVE A NICE SWATH OF
QPF WORKING DOWN WITH THE FRONT...BUT THE ECMWF CONTINUES TO BE DRY.
WITH THE GULF STILL CUT-OFF...THESE TYPES OF PATTERNS/FROPAS ARE
USUALLY DRY FOR US...SO DEFINITELY FAVOR THE DRIER ECMWF SOLUTION.
HOWEVER...WITH THE GEM/GFS IN THE BLENDING PROCEDURE USED...WE DO
HAVE POPS SPREAD ACROSS THE ENTIRE AREA SAT NIGHT...WITH THE HIGHEST
POPS OVER WI.

AFTER THIS WEEKEND...BOTH THE GFS/ECMWF SHOW THE REGION BEING DRY
UNTIL ANOTHER POWERFUL SPRING SYSTEM SHOWS UP TO WELCOME US TO APRIL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 719 AM CDT TUE MAR 24 2015

IFR/LOW MVFR CEILINGS COVER THE MN TAF SITES THIS AM. WE MAY
STRUGGLE FOR MUCH IMPROVEMENT IN THE MN RIVER VALLEY TODAY WITH A
MOIST SOUTHEAST LOW LEVEL FLOW WITH CEILINGS KEPT IN PLACE. LOW
MVFR CEILINGS MAY EVEN SNEAK BACK IN AT KRNH AND KEAU FOR A TIME
THIS MORNING ALTHOUGH CONFIDENCE IS NOT HIGH. SEVERAL RUNS OF THE
HRRR STILL SHOW THAT ANY MVFR CEILINGS FROM KMSP WILL MOVE OUT
EARLY THIS AFTERNOON. PRECIPITATION TRENDS HAVE CHANGED SOME SINCE
THE LAST TAF ISSUANCE. SHORT TERM SOLUTIONS ARE INDICATING A
SLOWER ONSET FOR THE TWIN CITIES ON EAST AND THIS WAS INCORPORATED
INTO THE NEW SET. A MIX OF RAIN AND SNOW SHOULD SWITCH OVER TO
SNOW FROM THE TWIN CITIES ON EAST AND SOUTH THIS EVENING WITH A
BAND OF MODERATE SNOW TO THE SOUTHEAST OF THE TWIN CITIES TO KEAU.
DRIER MID LEVEL AIR WILL WORK IN FROM THE SOUTHWEST LATE IN THE
NIGHT...ENDING PRECIP TO THE WEST AND SOUTH OF THE TWIN CITIES. SE
WINDS GUSTING 15-20 KNOTS TODAY VEERING WESTERLY LATE TONIGHT.

KMSP...LOW MVFR CEILINGS ARE BACK BUT EXPECT A BREAK OUT TO VFR
THIS AFTERNOON BEFORE DETERIORATING BACK DOWN TO LOW MVFR/IFR
TONIGHT. RAIN/SNOW SPREADING IN AFTER 25/00Z CHANGING TO ALL SNOW
BY 03Z AND CONTINUING UNTIL ABOUT 09Z. SNOWFALL RATES ARE EXPECTED
TO BE HIGHEST FROM 03Z-06Z WITH AROUND A 1/2 INCH PER HOUR.

/OUTLOOK FOR KMSP/

WED...MVFR. WINDS W 15G25 KTS.
THU...MVFR AND -SN POSSIBLE EARLY. WINDS NNW 15G25 KTS.
FRI...VFR. WINDS NW 5-10 KTS BCMG SW IN THE AFTN.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM CDT
     WEDNESDAY FOR MNZ082>085-091>093.

     WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
     WEDNESDAY FOR MNZ077-078.

WI...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM CDT
     WEDNESDAY FOR WIZ024>028.

&&

$$

SHORT TERM...RAH
LONG TERM...MPG
AVIATION...RAH


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