Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 020904
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
404 AM CDT SUN AUG 2 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SUN AUG 2 2015

TODAY AND TONIGHT...SFC ANALYSIS DEPICTS A SFC LOW OVER ERN SD THIS
MRNG WITH A WMFNT EXTENDING SEWD AND A CDFNT EXTENDING SWWD FROM
THIS CENTER. ISOLD CONVECTION OVERNIGHT DUE TO CONVERGENCE INVOF THE
WMFNT AND A LOCALIZED MIDLVL JET EVIDENT ON WV IMAGERY HAS SHIFTED
OFF TO THE E AND WEAKENED...RESULTING IN A MAINLY DRY START TO THE
DAY. KMPX RADAR SHOWS WEAK ECHOES DRIVING SEWD FROM NERN ND AND NRN
MN BUT MUCH OF THIS IS NOT REACHING THE GROUND WITHIN THE WFO MPX
CWFA. HOWEVER...AS THE DAY PROGRESSES...DEEP MIXING WILL STILL
PROMOTE 30-40 KT OF BULK SHEAR HIGHLIGHTED OVER FAR ERN MN INTO WRN
WI THIS AFTN AND EVE. BEST INSTABILITY AND FORCING ALOFT WILL BE
WELL SE OF THE CWFA...BUT STILL BEING IN THE WARM SECTOR OF THIS
SYSTEM WILL ALLOW FOR SOME SBCAPE TO DEVELOP WHICH WILL MAKE FOR
SOME ISOLD-SCTD TSTM DEVELOPMENT LATER TDA. HAVE MAINTAINED SLGT-LOW
CHC POPS IN ERN PORTIONS OF THE CWFA TO ACCOUNT FOR THIS. AS THE
CDFNT SWEEPS SEWD ACRS THE REGION TDA...THIS WILL BRING AN END TO
ANY AND ALL PRECIP BY THIS EVE. COOLER/DRIER HIGH PRES WILL THEN
BEGIN TO MAKE INROADS TO THE REGION TNGT...STARTING A DRYING OUT
PERIOD FOR THE REGION GOING INTO THE FIRST HALF OF THE WEEK.

TEMPERATURES WILL STILL RUN WARM IN ADVANCE OF THE CDFNT TDA. HIGHS
WILL GENERALLY RANGE 80-90 DEGREES NORTH-TO-SOUTH ACRS THE CWFA TDA.
WITH LATE AFTN TIMING OF THE COLD FROPA...THIS WILL START CAA THAT
WILL BE FELT FOR TNGT. LOWS TNGT INTO EARLY MON MRNG WILL FALL TO
THE 50S ACRS THE CWFA...WHICH WILL BE ABOUT 10 DEGREES COOLER THAN
LOWS EXPERIENCED THIS MRNG.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 400 AM CDT SUN AUG 2 2015

THE MAIN FEATURE OF NOTE IN THE LONG TERM PERIOD CONTINUES TO BE
THE LARGE UPPER LOW OVER HUDSON BAY. BY TOMORROW MORNING...THIS
FEATURE WILL BEGIN SAGGING SOUTH TOWARD THE UPPER GREAT LAKES
REGION. THE LONGWAVE TROUGH ASSOCIATED WITH THE LOW WILL BE IN
PLACE INTO AT LEAST WEDNESDAY...MEANING MONDAY AND TUESDAY WE WILL
REMAIN IN RELATIVELY COOL NORTHWEST FLOW...WITH LITTLE CLOUD COVER
OWING TO THE DRY AIR MASS COMING IN FROM CANADA. HIGH TEMPERATURES
WILL GENERALLY BE IN THE MID TO UPPER 70S ALL WEEK...SLIGHTLY
COOLER THAN NORMAL FOR THIS TIME OF YEAR.

IT LOOKS LIKE WE HAVE ONE DECENT CHANCE OF PRECIPITATION IN THE
LONG TERM PERIOD...AND THAT COMES ON WEDNESDAY INTO WEDNESDAY
NIGHT. THE AFOREMENTIONED UPPER LOW WILL BEGIN DRIFTING VERY
SLOWLY EAST BY WEDNESDAY AS A SHORTWAVE TROUGH ADVANCES EAST OVER
THE ALONG THE LONGWAVE RIDGE OVER THE WESTERN CONUS. AT THIS
TIME...THIS FEATURE LOOKS TO HAVE THE INGREDIENTS FOR A DECENT
RAINFALL MAKER. AS THE TROUGH PUSHED INTO MN...A CYCLONICALLY
CURVED JET STREAK AROUND THE LONG WAVE TROUGH TO OUR NORTHEAST
WILL PLACE THE UPPER MIDWEST IN A FAVORABLE AREA OF UPPER LEVEL
DIVERGENCE. IN ADDITION...STRONG THETA-E ADVECTION IS FORECAST
WEDNESDAY- WEDNESDAY NIGHT AS LOW LEVEL WINDS TURN SOUTHERLY ON
THE LEADING EDGE OF THE WAVE...AND WE MAKE A GULF MOISTURE
CONNECTION WITH PRECIPITABLE WATER VALUES INCREASING TO GREATER
THAN 1.5 INCHES. AT THE SURFACE...A FRONTAL BOUNDARY WILL LIFT
NORTH INTO THE UPPER MIDWEST WITH INCREASING SURFACE DEW POINTS AS
WELL. BEST LI VALUES BECOME NEGATIVE FOR MOST OF SOUTHERN MN BY
WEDNESDAY AFTERNOON...SO THERE IS SOME INSTABILITY TO WORK WITH AS
WELL. BEING 4 DAYS AWAY HOWEVER...CONFIDENCE IN THE PLACEMENT OF
POTENTIAL RAINFALL IS NOT HIGH...ESPECIALLY GIVEN THE VARIOUS
SOLUTIONS OFFERED BY THE DETERMINISTIC GUIDANCE...AND THE FACT
THAT THE HUDSON BAY UPPER LOW COULD WREAK HAVOC ON THE ENTIRE
UPPER AIR PATTERN. SO...DECIDED TO STICK WITH THE ALLBLEND
GUIDANCE FOR THIS PERIOD WHICH FOR NOW SUGGESTS CHANCE POPS.

SLIGHT CHANCE POPS LITTER THE FORECAST LATE IN THE WEEK AS A WEAK
FRONTAL BOUNDARY PUSHES INTO WESTERN MN...BUT AT THIS TIME THERE
IS LITTLE AGREEMENT IN SEEING ORGANIZED PRECIPITATION DURING THAT
PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1145 PM CDT SAT AUG 1 2015

A FEW SHOWERS HAVE FORMED EAST OF MSP...NEAR RNH AND EAU. THESE
WILL DIMINISH DURING THE NEXT COUPLE HOURS WITH DRY WEATHER EXPECTED
FOR THE REST OF THE NIGHT. A FEW MORE STORMS COULD DEVELOP SUNDAY
AFTERNOON ACROSS WESTERN WI. MAIN STORY SUNDAY WILL BE STRONGER
NORTHWEST WINDS BEHIND COLD FROPA WHEN SOME GUSTS COULD EXCEED 25
KT.

KMSP...A SHOWER OR TWO NEAR MSP WILL DIMINISH BY 06Z TAF
ISSUANCE...THEN DRY WEATHER EXPECTED FOR THE REST OF THE PERIOD.

/OUTLOOK FOR KMSP/
MON...VFR. WIND NW 10-15KTS.
TUE...VFR. WIND N 5-10KTS.
WED...VFR. WIND SE 5-10KTS.


&&

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

$$

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



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