National Weather Service Raw Text Product

872 
FXUS63 KMPX 220512
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1212 AM CDT MON APR 22 2013

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 310 PM CDT SUN APR 21 2013

STRONG 80-100M 500MB 12-HR HEIGHT FALLS JUST WEST OF LAKE WINNIPEG
THIS AFTERNOON. SHORTWAVE EVIDENT ON WATER VAPOR STRETCHING SOUTH
ACROSS THE EASTERN DAKOTAS AND EASTERN NE. THIS AREA LINES UP JUST
TO THE WEST OF THE SURFACE TROUGH AND COLD FRONT WHICH IS DENOTED
ON RADAR BY THE BAND OF SHOWERS CURRENTLY MOVING TO THE EAST AT
20-25 KTS. THE AREA OF RAIN WILL CONTINUE RIGHT ON THROUGH THE
AFTER NOON AND EVENING AND COULD ACTUALLY EXPAND SLIGHTLY IN
COVERAGE AND/OR INTENSITY EARLY THIS EVENING. THERE ISN'T MUCH OF
A TEMPERATURE CHANGE IMMEDIATELY BEHIND THE FRONT /THOSE ARE
FARTHER UPSTREAM/ ...BUT THERE IS A NOTABLE WIND SHIFT TO THE
NORTHWEST BEHIND THE FRONT. STILL GOOD AGREEMENT IN A QUARTER INCH
FOR THE QPF ACROSS EASTERN MN AND WESTERN WI...AMOUNTS SHOULD NOT
BE QUITE AS HIGH IN WESTERN MN. STILL A SMALL CHANCE FOR A RUMBLE
OF THUNDER OR TWO IN FAR SOUTHERN MN. SREF PROBS FOR THUNDER AND
SPC GENERAL THUNDER OUTLOOK STILL HIGHLIGHT SOUTHERN MN THIS
EVENING.

SHOULD BE A SIZABLE BREAK IN THE PRECIP BEFORE AN INVERTED TROUGH 
TO OUR SOUTH DEEPENS INTO A SURFACE LOW IN NORTHERN ILLINOIS BETWEEN 
00-12Z TUESDAY. THIS WILL BRING ABOUT WHAT COULD BE OUR LAST BOUT OF 
ACCUMULATING SNOW FOR THE SEASON. MID-LEVEL FRONTOGENESIS AND OMEGA 
ARE QUITE GOOD OVER THE FORECAST AREA /ESPECIALLY THE EASTERN HALF/ 
TOMORROW AFTERNOON AND EVENING. THE QPF SHOULD NOT BE A PROBLEM WITH 
0.25-0.75" OVER A LARGE AREA NEAR THE MID LEVEL FRONT. P-TYPE IS A 
QUESTION. GIVEN THE TIME OF DAY FOR THE ONSET OF PRECIP AND THE LAG 
OF 6-9 HOURS OF WHEN THE COLDEST AIR FILTERS IN...EASTERN MN AND 
WESTERN WI COULD LOSE A LOT OF SNOW TO RAIN. HOWEVER...THERE WILL 
ALMOST CERTAINLY BE AN OVERLAP OF THE COLD AIR AND WESTERN EDGE OF 
THE QPF MAX...THIS AREA WOULD LIKELY STRETCH FROM FAIRMONT...TO THE 
WESTERN TWIN CITIES METRO...TO RICE LAKE WI. THE 21.12Z GFS SHIFTED 
BACK TO THE WEST SLIGHTLY AND NOW THE 21.12Z GFS AND ECMWF ARE IN 
FAIRLY CLOSE THE AGREEMENT ON TIMING AND SNOW AMOUNTS OF 2-5" ACROSS 
EASTERN MN AND WESTERN WI. ADMITTEDLY...THE GFS IS STILL A BIT 
FARTHER EAST WITH THE HEAVIEST SNOW AS COMPARED TO THE ECMWF. OUR 
FORECAST SNOW AMOUNT FOR THE TWIN CITIES METRO IS BETWEEN 3-4" AND 
THE ACCUMULATING SHOULD LARGELY OCCUR BETWEEN 7 PM AND 12 AM. 

.LONG TERM...(TUESDAY THROUGH SUNDAY) 
ISSUED AT 310 PM CDT SUN APR 21 2013

CDFNT WILL BE CLEAR OF THE WFO MPX CWFA BY DAYBREAK ON TUE...SO
SAVE FOR A FEW LINGERING RAIN/SNOW SHOWERS IN THE MRNG...PRECIP
WILL COME TO AN END FOR THE AREA. FOLLOWING THE SYSTEM WILL BE
MODEST NW FLOW...ALLOWING FOR SOME CAA ON THE BACKSIDE OF THE
EXITING SYSTEM. THIS WILL KEEP TEMPERATURES COOLER THAN WHAT WAS
EXPERIENCED ON SUNDAY...WITH HIGHS ONLY IN THE LOW-MID 40S DESPITE
PARTIALLY CLEARING SKIES TUE-WED. WED LOOKS TO HAVE A QUICK-MOVING
SYSTEM SWING ON THROUGH...AND THIS DOES LOOK POTENTIALLY POTENT
WHAT WITH THE NAM/EC/GFS/GEM SHOWING A NEGATIVELY TILTED H5 TROF
PIVOTING OVER THE AREA. THERE IS ALSO A DECENT SLUG OF HEIGHTENED
MOISTURE CONTENT THAT WILL AID IN QPF. THEREFORE...HAVE NUDGED UP
POPS INTO THE HIGH-END CHC CATEGORY FOR MAINLY LATE DAY WED INTO
WED NIGHT. THE PRECIP WILL START OUT AS RAIN WED THEN TRANSITION
TO SNOW WED NIGHT...BUT ANY ACCUMULATIONS WILL BE LESS THAN AN
INCH WITH LOWS DROPPING TO THE UPPER 20S TO ARND 30. ONCE THIS
FRONT EXITS...THEN A PROLONGED DRYING OUT PERIOD LOOKS TO DEVELOP
OVER THE AREA. MODELS ARE IN HIGH DISAGREEMENT ON THE PROGRESSION
OF THE UPPER FLOW AND OF THE DEVELOPMENT OF SFC SYNOPTIC FEATURES.
THERE MAY BE A WEAK MIDLVL DISTURBANCE AND SFC TROUGH SWING THRU
THE AREA THU AND/OR FRI...BUT MODELS BARELY SQUEEZE OUT 0.01 INCH
QPF. THEREFORE...HAVE OPTED TO RUN WITH A DRY FCST FOR THE REGION
THU THRU SAT. A MORE ORGANIZED SYSTEM LOOKS TO AFFECT THE REGION
BY SUNDAY...BUT TEMPERATURES WILL BE WELL ABOVE FREEZING AT THAT
POINT SO AM FINALLY ABLE TO ADVERTISE A FORECAST PERIOD WITHOUT
SNOW. TEMPERATURES GRADUALLY RISE THROUGH THE WEEK...WITH HIGHS
AROUND 60 BY NEXT WEEKEND AND LOWS IN THE 40S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1154 PM CDT SUN APR 21 2013

MAIN CONCERN FOR THE FIRST 6 HRS IS ASSOCIATED WITH CLEARING LINE
ACROSS NW MN...AND WHETHER ENOUGH DRYING AT LOW LEVELS HELPS TO
ERODE THE IFR/MVFR CLDS ACROSS THE FA. AXN HAS THE BEST CHC OF VFR
CONDS AFT 8Z...BUT WITH WINDS DECREASING TO LESS THAN 5 KTS...BR
OR EVEN FG MAY FORM DUE TO PRECIPITATION ON SUNDAY AND SOME SNOW
MELT. ELSEWHERE...THIS IS HIGHLY DEPENDENT ON THE AMT OF MIXING
OF THE DRIER AIR IN THE LOWEST 1KM. WILL LEAN TOWARD MVFR CIGS FOR
MOST TAFS...BUT STC/RWF COULD SEE VFR CONDS BY 9-11Z IF THE DRIER
AIR IS MORE DEVELOPED. AFT 12Z...TAFS IS HIGHLY DEPENDENT ON THE
INITIAL DRY AIR MASS BELOW 1KM...AND CRITICAL TEMPS IN THE
BOUNDARY LAYER...UP TO 1 KM. MODELS HAVE BEEN TRENDING TOWARD A
REDEVELOPMENT OF SNOW AT RWF BY 15-17Z WITH MODERATE TO HEAVY
SNOWFALL BY THE AFTN/EVENING HRS. AXN WILL LIKELY BE ON THE EDGE
OF THE HEAVIEST SNOWFALL...SO WILL LEAN ON ONLY A FEW HRS OF IFR
IN -SN. STC WILL LIKELY SEE THE BULK OF THE -SN AFT 21Z...WITH
MODERATE SNOW BETWEEN 00-06Z. RNH WILL BE ON THE EDGE OF A MIXTURE
OF RA/SN BEFORE 00Z...THEN ALL SNOW WITH MODERATE/HEAVY SNOW AFT
00Z. EAU WILL LIKELY REMAIN ALL LIQUID UNTIL AFT 6Z. WINDS WILL
CONTINUE OVERNIGHT FROM THE NW/N...AND VEER TO THE N/NNE MONDAY
MORNING AND INCREASE IN SPD. WINDS SHOULD BEGIN TO BACK TO THE NW
MONDAY EVENING. 

KMSP...

THERE COULD BE A PERIOD OF VFR CONDS AFT 11Z...AND UNTIL 15Z AS
DRIER AIR BELOW 1KM FILTERS SOUTHEAST ACROSS THE REGION. NO
PRECIPITATION WILL OCCUR UNTIL AFT 18Z...WITH MODERATE TO HEAVY
PRECIPITATION DEVELOPING BY 00Z. A MIXTURE OF RAIN/SNOW IS LIKELY
DURING THE AFTN BEFORE CHANGING OVER TO ALL SNOW MONDAY EVENING.
IT WILL BE HEAVY AT TIMES DURING THE EVENING WITH IFR/LIFR
CIGS/VSBYS IN SNOW. AFT 6Z...EXPECT A SLOW IMPROVEMENT AS THE
SYSTEM MOVES OUT OF THE REGION TUESDAY MORNING. WINDS WILL
CONTINUE FROM THE NW OVERNIGHT...VEER TO THE N/NNE MONDAY
MORNING...THEN MORE N/NNW...THEN NW MONDAY EVENING. 

/OUTLOOK FOR KMSP/

TUE...MVFR IN THE MRNG...THEN VFR. NW WINDS 10-15 KTS. 
WED...VFR. CHC MVFR/-RASN AFTN. SW WINDS 10-15 KTS.
THU...VFR. W WINDS 10 KTS.

&&

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

$$

SHORT TERM...CLF
LONG TERM...JPC
AVIATION...JLT