Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 310848
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
348 AM CDT THU JUL 31 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM CDT THU JUL 31 2014

EARLY MORNING SURFACE ANALYSIS SHOWED A WEAK ZONAL
PRESSURE TROUGH DRAPED ACROSS THE ARROWHEAD OF MN...WITH THE SURFACE
RIDGE CENTERED ACROSS THE DAKOTAS. AS A RESULT OF THIS RELAXED
PRESSURE FIELD THE WIND WERE LIGHT AND GENERALLY HAD A SOUTH
WESTERLY COMPONENT.

LATER THIS MORNING FORECAST SOUNDINGS SHOW NORTHERLY WINDS RETURNING
AS DIABATIC HEATING MIXES OUT THE NOCTURNAL INVERSION. WITH
RELATIVELY DRY AIR IN PLACE...THE FEW AFTERNOON CUMULUS THAT DEVELOP
WILL HAVE BASES GENERALLY IN THE 4-6KFT RANGE. THIS AFTERNOON A
SUBTLE PV ANOMALY CURRENTLY LOCATED OVER NORTH DAKOTA WILL SLIDE
SOUTHWARD AND DRAG THE SURFACE TROUGH WITH IT. ISOLATED SHOWERS AND
THUNDERSTORMS WILL DEVELOP ALONG THE UPPER MISSOURI RIVER
VALLEY...BUT SHOULD REMAIN SOUTH AND WEST OF THE FORECAST AREA.
MEANWHILE HIRES MODELS SUCH AS THE MPXWRF...NMM...ARW...AND EVEN THE
LAST FEW HOURS OF THE HRRR INDICATE LATE AFTERNOON CONVECTION ACROSS
WESTERN WI AND FAR EASTERN MN ONCE AGAIN. ALTHOUGH CONFIDENCE IN
OCCURRENCE IS HIGH...COVERAGE WILL BE LOW SO CONTINUE WITH 20 PERCENT
POPS. AS WAS THE CASE YESTERDAY...FEW STRONG WIND GUSTS ARE POSSIBLE
UNDER THE HEAVIER PRECIP CORES GIVEN THE INVERTED V SOUNDINGS. THE
ISOLATED CONVECTION WILL TAPER OFF AFTER SUNSET...WITH ANOTHER QUIET
NIGHT IN STORE THURSDAY NIGHT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM CDT THU JUL 31 2014

ONE MORE BROKEN RECORD DAY WILL OCCUR FRIDAY WITH SCATTERED
AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS EASTERN MN
AND WESTERN WI AS ANOTHER WEAK WAVE ROTATES AROUND THE SLOWLY
DEVOLVING SOUTHERN HUDSON BAY UPPER LOW. ECMWF IS MOT GENEROUS
WITH DEVELOPMENT...WHILE THE GFS AND NAM CONFINE THE BEST
COVERAGE TO SRN WI. MAINTAINED CHC POPS FOR THE EASTERN
AREAS...PRIMARILY BETWEEN 4-7 PM.

THE PATTERN WILL FINALLY DEAMPLIFY SOMEWHAT THIS WEEKEND WITH THE
EASTERN TROUGH EASING AND THE WESTERN TROUGH SPILLING SOUTHEAST
INTO THE PLAINS. THIS WILL KEEP THE UPPER LEVELS WEST NORTHWEST
ACROSS THE MIDWEST FOR THE REMAINDER OF THE LONG TERM. WHILE IT
WILL BRING SLIGHTLY WARMER TEMPS INITIALLY FOR THIS WEEKEND...IT
WILL ALSO BRING INCREASING CHANCES FOR THUNDERSTORMS AND HEAVY
RAINFALL EARLY NEXT WEEK. INTERESTINGLY...FOR THE PAST SEVERAL
WEEKS THE CFS HAS GENERALLY BEEN CALLING FOR A DRY SECOND HALF OF
JULY FOLLOWED BY A DECENT HEAVY RAIN EVENT FOR THE FIRST OR SECOND
WEEK OF AUGUST.

AFTER A CLEAR SATURDAY...CLOUDS WILL INCREASE AND CHANCES OF
STORMS WILL REENTER THE PICTURE LATE SATURDAY NIGHT ACROSS CENTRAL
MN...EXPANDING SOUTHEAST THROUGH WESTERN WISCONSIN SUNDAY WITH A
WEAK SHORTWAVE.

THE MAIN SHOW WILL ORIGINATE OVER THE DESERT SOUTHWEST WITH
MONSOONAL MOISTURE. THIS DISTURBANCE WILL TRACK NORTH AND EAST
AROUND THE UPPER RIDGE CENTERED OVER THE SOUTHERN PLAINS EARLY
NEXT WEEK. MODELS ARE IN GENERALLY GOOD AGREEMENT WITH THE OVERALL
SCENARIO SET TO PLAY OUT...BUT AS CAN BE EXPECTED 5 TO 6 DAYS
OUT...DIFFERENCES ARE SIGNIFICANT ENOUGH TO REDUCE CONFIDENCE ON
PLACEMENT AND TIMING OF THE BEST RAINFALL. GENERALLY PREFER THE
ECMWF AND GFS ENSEMBLE MEAN WHICH ARE FAVORING SIMILAR SOLUTIONS AND
ARE QUITE DIFFERENT THAN THE OPERATIONAL GFS WHICH IS MUCH FURTHER
NORTH THAN THE REST OF THE GUIDANCE ENVELOPE.

MID LEVEL WINDS SHOULD BE SUFFICIENTLY WEAK TO GREATLY LIMIT THE
THREAT FOR SEVERE WEATHER...BUT MAY FAVOR A HEAVY RAIN SCENARIO
WITH A SLOW MOVING OR BACK BUILDING MCS ALONG THE STATIONARY FRONT
TUESDAY NIGHT/EARLY WEDNESDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 348 AM CDT THU JUL 31 2014

POCKETS OF FOG WILL QUICKLY DISSIPATE WITH VFR CONDITIONS
EXPECTED ACROSS THE REGION TODAY AND TONIGHT. LIGHT...VARIABLE
WINDS WILL GRADUALLY BECOME NORTHWESTERLY TODAY AT AROUND 5 TO 10
KTS. A FEW SHOWERS AND THUNDERSTORMS SHOULD DEVELOP ACROSS FAR
EASTERN MN AND WESTERN WI AGAIN LATER THIS AFTERNOON...BUT
COVERAGE WILL BE LIMITED TO DID NOT INCLUDE ANY MENTION IN THE
TAFS.

KMSP...
VFR CONDITIONS THROUGHOUT. CONFIDENCE IS TOO LOW TO INCLUDE ANY
MENTION OF PRECIP IN THE TAFS AT THIS TIME...BUT THE MOST LIKELY
PERIOD WITH THE HIGHEST COVERAGE ACROSS THE REGION WILL BE FROM 22
TO 01.

/OUTLOOK FOR KMSP/
SAT...VFR. WINDS VARIABLE 5 KTS.
SUN...VFR WITH MVFR/TSRA POSSIBLE. WINDS SW 5-10 KTS.
MON...VFR WITH MVFR/TSRA POSSIBLE. WINDS SW 5-10 KTS.


&&

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

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JRB





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