Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 190801
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
301 AM CDT SUN APR 19 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT SUN APR 19 2015

TODAY AND TONIGHT...SFC ANALYSIS PUTS A SFC LOW PRES CENTER NEAR
KBDH WITH A CDFNT EXTENDING SWWD INTO THE SRN PLAINS BUT ALSO A SFC
TROF EXTENDING NWD INTO SRN MANITOBA. THESE FEATURES ARE UNDERNEATH
A SHARP H5 LONGWAVE TROF AXIS OVER THE DAKOTAS AND THE LEE OF THE
ROCKIES WHILE A WEAKENED CUTOFF LOW EJECTS FROM THE SWRN CONUS. THE
UPR TROF WILL ABSORB THE SRN UPR LOW...AIDING IN EXPANDING THE TROF
OVER THE NRN-CENTRAL PLAINS AND INTO THE UPR-MID MISS RIVER VALLEY
REGIONS THRU TNGT. THOUGH THERE IS LITTLE DOUBT IN THESE LARGER-
SCALE FEATURES...THE CHALLENGE COMES IN HOW THE DRY SLOT EVIDENT ON
KMPX RADAR OVER THE CENTRAL PORTIONS OF THE CWFA...IN FACT EVEN WELL-
PLACE OVER THE I-35 CORRIDOR...WILL PLAY A FACTOR IN THE RW-
DISTRIBUTION OVER THE CWFA THRU THIS SHORT-TERM PERIOD. HIGH
CONFIDENCE REMAINS IN MUCH OF THE CWFA SEEING SPRINKLES TO LIGHT
RAIN SHOWERS THRU THE FIRST HALF OF THE DAY...BUT QPF AMOUNTS WILL
BE MUCH LESS THAN ANTICIPATED DUE TO THE LARGER AREA OF DRY SLOTTING
MOVG NEWD IN CONJUNCTION WITH THE SFC LOW. HRRR/NAM/HOPWRF DO TRY TO
FILL MOISTURE BACK INTO THE AREA...RESULTING IN ADDITIONAL PRECIP
THIS AFTN/EVE...BUT NOT UNTIL THE CDFNT HAS SHIFTED TO THE MN/WI
BORDER WHICH WOULD CONFINE THE BULK OF THE PRECIP TO THE WRN WI
COUNTY PORTION OF THE WFO MPX CWFA. HAVE STRUCTURED GRIDDED POPS AS
SUCH...DROPPING POPS FROM W TO E THRU THE DAY TDA. IN ADDITION...
THE MEAGER INSTABILITY...LACK OF GOOD INSOLATION DUE TO EXTENSIVE
CLOUD COVER AND POORER LAPSE RATES INDICATE A MUCH LESSER CHC AT
CONVECTION SO HAVE OMITTED THUNDER MENTION THIS MRNG. PRECIP WILL
GRADUALLY END THIS EVE INTO THE EARLY MRNG HOURS SUCH THAT BY
DAYBREAK MON MRNG...PRECIP IS NO LONGER EXPECTED.

AS FOR TEMPERATURES...THE COLD FROPA WILL COMMENCE CAA FOR THE AREA
BUT THE EXPANSION OF THE UPPER TROF...MAKING FOR NW FLOW ALOFT...
WILL BE THE MAIN PLAYER IN BRINGING IN COLDER AIR THAT WILL REMAIN
IN PLACE GOING FORWARD. MILD TEMPS IN THE MID 40S TO MID 50S THIS
MRNG WILL ONLY RANGE FROM THE MID 50S TO MID 60S TDA. WITH DEEP NW
FLOW TNGT...LOWS WILL DROP TO THE MID-UPR 30S...WHICH IS NEAR TO
SLIGHTLY BELOW NORMAL FOR LATE APRIL.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 300 AM CDT SUN APR 19 2015

WATER VAPOR IMAGERY THIS MORNING CLEARLY SHOWED TWO DISTINCT
FEATURES OF CONCERN FOR THE LONG TERM PERIOD.  THE UPPER LEVEL LOW
PUSHING FROM COLORADO INTO WESTERN KANSAS...AND A SHARP SHORTWAVE
TROUGH EXTENDING FROM THE SASKATCHEWAN/MANITOBA BORDER THROUGH
EXTREME EASTERN MONTANA AND WYOMING.  THE UPPER LOW HAS BEEN QUASI-
STATIONARY FOR DAYS NOW...BUT THE PROGRESSIVE SHORTWAVE WILL HELP
IT FINALLY GAIN SOME STEAM TO THE EAST. BY MONDAY MORNING...THE
SHORTWAVE WILL DEEPEN AND BECOME A CLOSED LOW AT 500MB AND THE
CENTER OF IT WILL BE OVER WESTERN ONTARIO.  AT 850MB AND THE
SURFACE...WE`LL BE SQUARELY WITHIN THE COLD AIR ADVECTION REGIME...
AND STRONG NORTHWEST WINDS.  DEEP MIXING AND A STRONG PRESSURE
GRADIENT ACROSS THE AREA ON MONDAY WILL PERSIST INTO TUESDAY AS WELL
AS LOW PRESSURE AT THE SURFACE OVER THE GREAT LAKES MOVES NORTH
TOWARD HUDSON BAY.  A WIND ADVISORY WILL BE A POSSIBILITY FOR MONDAY
AFTERNOON...BUT LATER SHIFTS WILL MAKE THE CALL ON THAT.
GENERALLY...20 TO 30 MPH NORTHWEST WINDS WITH GUSTS OF 30 TO 40 MPH
ARE EXPECTED ON MONDAY...AND ABOUT 15 TO 25 MPH WITH GUSTS TO 30 ON
TUESDAY. TEMPERATURES WILL RUN ABOUT 10 TO 15 DEGREES BELOW
NORMAL...SO A STARK DIFFERENCE FROM THE RECENT WARM STRETCH WE`VE
EXPERIENCED.  IN TERMS OF PRECIPITATION...STILL EXPECT SHOWERY
ACTIVITY TO DEVELOP IN THE CYCLONIC FLOW ACROSS OUR AREA FOR MONDAY
AND TUESDAY. MID LEVEL LAPS RATES LOOK STEEP ENOUGH TO HELP PRODUCE
SAID SHOWERS. SURFACE TEMEPRATURES WILL COOL INTO THE LOW AND MID
30S MONDAY NIGHT...SO SNOW SHOWERS ARE ALSO A POSSIBILITY DURING
THAT TIME.

FOR WEDNESDAY THROUGH SATURDAY...THE MAIN FOCUS IS THE
AFOREMENTIONED UPPER LOW THAT WILL MOVE OVER THE NORTHERN GREAT
LAKES AND BECOME QUASI-STATIONARY...KEEPING OUR REGION IN THE
BACKSIDE OF THE TROUGH AND NORTHWEST FLOW...MEANING CONTINUED COOL
TEMPERATURES. TOWARD THE END OF THE WEEK...THE GFS AND ECMWF REALLY
BEGIN TO DIVERGE IN THEIR HANDLING OF THIS LOW.  THE ECMWF IS MORE
PROGRESSIVE IN SLOWLY PUSHING IT EAST AND TRYING TO PUSH THE UPPER
RIDGE INTO THE UPPER MIDWEST BY NEXT WEEKEND.  THE GFS INDICATES A
SECONDARY UPPER LOW TO THE NORTHWEST OF THE MAIN LOW WILL BE PULLED
SOUTH AND MOVE THROUGH THE WESTERN GREAT LAKES REGION NEXT
WEEKEND...WHICH WOULD KEEP US COOLER AND POSSIBLY GIVE US SOME
PRECIP.  WITH THE DISAGREEMENT BEYOND THURSDAY...NOT TOO CONFIDENT
IN EITHER SOLUTION SO STUCK WITH A BROAD BLEND AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1119 PM CDT SAT APR 18 2015

RAIN MOVING IN TONIGHT. THE 06Z TAF REFLECTS THE BEST ESTIMATE ON
TIMING. WE DON`T THINK THERE WILL BE MUCH IN THE WAY OF IFR...BUT
CERTAINLY PLENTY OF MVFR CEILINGS LATE TONIGHT AND EARLY TOMORROW
MORNING.

KMSP...
NOT MUCH TO ADD...STEADY LIGHT RAIN SETS IN TONIGHT AND LAST
THROUGH THE MORNING TOMORROW. WE THINK THE VIS WILL REACH 4SM
BRIEFLY AND THE CEILING SHOULD GET CLOSE TO 2000 FT EARLY IN THE
MORNING...BUT WE ARE SOMEWHAT UNSURE ON WHEN SPECIFICALLY THAT
WILL HAPPEN. THE TAF REPRESENTS ARE BEST ESTIMATE ON TIMING.
CERTAINLY LOOKS LIKE A SOGGY EARLY MORNING.

/OUTLOOK FOR KMSP/
MON...VFR WITH MVFR/-SHRA POSSIBLE. WINDS NW AT 20G35KTS.
TUE...VFR. WINDS NW AT 15G25KTS.
WED...VFR. WINDS NW AT 15G25KTS.


&&

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

$$

SHORT TERM...JPC
LONG TERM...SPD
AVIATION...CLF


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