Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 270535
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1235 AM CDT THU AUG 27 2015

.UPDATED FOR 06Z AVIATION DISCUSSION BELOW...

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 401 PM CDT WED AUG 26 2015

HIGH PRESSURE WAS CENTERED OVER THE TWIN CITIES AT MID AFTERNOON
ACCOMPANIED BY NEARLY CALM WINDS AND RELATIVE HUMIDITY IN THE 40 TO
45 PERCENT RANGE. THE HIGH WILL DRIFT SLOWLY EAST TONIGHT. THIS WILL
ALLOW FOR LOWS IN EASTERN MINNESOTA OUTSIDE THE METRO TO DROP INTO
THE LOWER 50S...WITH MIDDLE TO UPPER 40S IN WEST CENTRAL
WISCONSIN. PATCHY FOG IS FORECAST ONCE AGAIN FOR PORTIONS OF
CENTRAL MINNESOTA AND WEST CENTRAL WISCONSIN.

IN THE WAKE OF THE HIGH ON THURSDAY...SOUTHEAST SURFACE WINDS WILL
BEGIN TO INCREASE ACROSS THE AREA. LOW LEVEL MOISTURE TRANSPORT WILL
SPREAD INTO WEST CENTRAL AND SOUTHWEST MINNESOTA DURING THE
DAY...AHEAD OF A VIGOROUS LOW PRESSURE SYSTEM MOVING INTO THE
CENTRAL PLAINS. WEST CENTRAL AND SOUTHWEST MINNESOTA WILL ALSO SEE
INCREASING INSTABILITY DEVELOPING DURING THE DAY AS WELL. THE
SITUATION IS SIMILAR TO THIS MORNING WHEN A SMALL BAND OF
THUNDERSTORMS DEVELOPED NEAR KABR AND DROPPED SOUTHEAST THROUGH THE
MORNING AND EARLY AFTERNOON HOURS. THE ONE DIFFERENCE IS THAT MID
LEVEL FLOW WILL BE MORE ANTICYCLONIC ON THURSDAY DUE TO THE STORM
SYSTEM ARRIVING FROM THE WEST...WHEREAS THIS MORNING WE HAD A
WEAK SHORT WAVE MOVING SOUTHEAST ACROSS EASTERN SOUTH DAKOTA.
NEEDLESS TO SAY...MOST CAMS ARE SHOWING SOME SHOWER AND
THUNDERSTORM ACTIVITY PUSHING IN FROM EASTERN SOUTH DAKOTA FROM
LATE MORNING ONWARD WITH THE MOST CONCENTRATED ACTIVITY IN THE
AFTERNOON ACROSS SOUTHWEST AND SOUTH CENTRAL MN NEAR THE I-90
CORRIDOR.

AT THIS POINT...PUSHED CHANCE TO LIKELY POPS ACROSS THE
AFOREMENTIONED AREAS DURING THE AFTERNOON. THE ONE CONCERN IS THAT
IT MAY COME QUICKER AND HIGHER POPS MAY BE NEEDED SOONER (THURSDAY
MORNING). HIGH TEMPERATURES WILL LIKELY BE HELD TO THE LOWER 70S
ACROSS FAR SOUTHERN MN ON THURSDAY WITH MIDDLE TO UPPER 70S TO THE
NORTH AND EAST.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 401 PM CDT WED AUG 26 2015

TWO THINGS CAN BE SAID ABOUT THE LONG TERM. ONE...MODELS ARE
BEGINNING TO HONE IN ON A SOLUTION FOR THE TRACK OF A HEAVY RAIN
EVENT THU NIGHT/FRIDAY ALONG THE I-90 CORRIDOR. TWO...AFTER A TASTE
OF FALL THIS WEEK...A SIGNIFICANT PATTERN SHIFT WILL BRING SUMMER
LIKE WEATHER BACK NEXT WEEK.

THE WAVE OF INTEREST FOR THU NIGHT/FRIDAY IS NOW MOVING ACROSS UTAH
AND WILL CONTINUE TO ROUND THE UPPER RIDGE CENTERED OVER
NM/CO...EVENTUALLY MOVING ALONG THE MN/IA BORDER FRIDAY. WITH THE
12Z MODEL RUNS...WE HAVE SEEN MODELS START TO HONE IN ON PRODUCING
THE HEAVIEST PRECIP ALONG THE I-90 CORRIDOR...LIKELY IN THE FORM OF
2-3 INCHES OF RAIN. THOUGH THIS AMOUNT SEEMS A BIT EXCESSIVE
CONSIDERING THE FACT THAT INSTABILITY AND THEREFORE CONVECTION WILL
BE LACKING...THIS WAVE WILL BE JUICED...WITH PWATS PUSHING
1.75"...WHICH IS NEAR THE CLIMATOLOGICAL MAX FOR STC/MPX FOR THE END
OF AUGUST. IN ADDITION...IT/S NOT JUST H85 MOISTURE TRANSPORT THAT
IS STRONG...BUT SW MID LEVEL JET IN EXCESS OF 40 KTS OUT AHEAD OF
THE WAVE WILL ENSURE DEEP MOISTURE TRANSPORT AT THE NOSE OF THE LOW
LEVEL AND MID LEVEL JETS...AIDING IN THE HIGHER PRECIP AMOUNTS
EXPECTED. THERE WILL BE A TIGHT GRADIENT IN QPF AS WELL...WITH VERY
LITTLE PRECIP EXPECTED ACROSS CENTRAL MN. FOR QPF...STUCK CLOSE TO
WHAT WPC HAS...WHICH IS A GOOD BLEND BETWEEN THE GFS/ECMWF.

FOR CHANGES MADE TO THE GOING FORECAST THU NIGHT/FRIDAY...KEPT THE
NRN EDGE OF MENTIONABLE PRECIP UNCHANGED...BUT DRAGGED THE LIKELY
AND HIGHER POPS QUITE A BIT FARTHER NORTH...WITH MODEL AGREEMENT
PRETTY GOOD IN SPREADING PRECIP UP THROUGH WILLMAR...ACROSS THE TWIN
CITIES AND TOWARD LADYSMITH. ALSO SLOWED POPS A BIT ACROSS THE AREA
FRIDAY INTO FRIDAY EVENING AS THE 12Z ECMWF SLOWED THE PROGRESSION
OF THE SYSTEM A BIT. LOOKS VERY LIKELY THAT FRIDAY MAY PRETTY MUCH
BE A WASHOUT ACROSS MUCH OF SOUTH CENTRAL INTO EAST CENTRAL MN.

BEHIND THIS SYSTEM...THE GFS/ECMWF CONTINUE TO BE IN GOOD AGREEMENT
WITH H5 HEIGHTS RAPIDLY BUILDING ACROSS THE AREA ON SATURDAY AS A
DEEP THROUGH DIGS INTO THE PAC NW AND RIDGING BEGINS TO BUILD UP
INTO THE GREAT LAKES. BY SUNDAY...THE ECMWF SHOWS H85 TEMPS BUILDING
TO A FEW DEGREES ON EITHER SIDE OF 24C...WHICH REMAIN IN PLACE
THROUGH THE REMAINDER OF THE WEEK. THESE SORT OF H85 TEMPERATURES
WILL SUPPORT HIGHS IN THE MID/UPPER 80S ALL OF NEXT WEEK...WITH A
FEW 90S NOT OUT OF THE QUESTION EITHER...ESPECIALLY IN WRN MN. WE
STILL HAVE A SMALL MENTION FOR PRECIP TUE/WED IN RELATION TO A FRONT
THAT WILL BE WASHING OUT ACROSS THE AREA. HOWEVER...WITH THE RIDGE
OVERHEAD...WE LOOK TO REMAIN CAPPED NEXT WEEK...SO DOUBT THIS WASHED
OUT FRONT WILL DO MUCH OF ANYTHING. IN FACT...THE GFS/ECMWF DO NOT
SHOW MUCH OF A CHANCE FOR PRECIP UNTIL LABOR DAY WEEKEND WITH THE
UPPER RIDGE REMAINING IN CONTROL NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1230 AM CDT THU AUG 27 2015

VFR CONDITIONS EXPECTED THROUGH MN PORTION OF THE FA WITH AREAS OF
LIFR/IFR FOG OVER WEST CENTRAL WI THROUGH 13Z THU.

SOME MID/HIGH LEVEL CLOUDS SPREADING EAST/SOUTHEAST ACROSS MN
OVERNIGHT INTO THURSDAY. SOME THREAT OF -SHRA INTO THU MORNING
OVER THE WEST...BUT EXPECT THAT TO GRADUALLY DRY UP DURING THE
LATE MORNING. THEN LOWERING CEILINGS INTO THE LATE
AFTERNOON/EVENING WITH APPROACH OF NEXT TROUGH. SOME -TSRA THREAT
MAINLY TO THE SOUTHWEST/KRWF REGION INTO THE EVENING BEFORE MORE
WIDESPREAD -SHRA/RA DEVELOPS OVERNIGHT ACROSS THE SOUTHERN THIRD
OF MN.

KMSP...
VFR CONDITIONS EXPECTED THROUGH AT LEAST 06Z FRI. THEN MORE
WIDESPREAD -SHRA/RA BR EXPECTED INTO THE AREA WITH MVFR CIGS
DEVELOPING LATE. SOME THREAT OF THUNDER...BUT BELIEVE THAT WILL
BE LIMITED TO SOUTHWEST MN AT THIS TIME. LIGHT SOUTHEAST WIND
INTO THE NIGHT GENERALLY 10KTS OR LESS.

/OUTLOOK FOR KMSP/
FRI...VFR. CHC MVFR SHRA/TSRA. WINDS SE 7-15 KTS.
SAT...VFR. WINDS SE 5-10 KTS.
SUN...VFR. WINDS S 5-10 KTS.

&&

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

$$

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


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