Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 270010
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
710 PM CDT WED AUG 26 2015

.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 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 710 PM CDT WED AUG 26 2015

VFR EXPECTED FROM WEST CENTRAL INTO MUCH OF SOUTHERN MN. SOME
CHANCE OF FOG LATE TONIGHT FROM CENTRAL MN INTO WEST CENTRAL WI.

A LOBE OF MID AND HIGH LEVEL CLOUDS EXTEND FROM THE SYSTEM OVER
THE NORTHERN/CENTRAL ROCKIES...AND THIS WILL DRIFT OVER THE AREA
TONIGHT. MEANWHILE...SURFACE HIGH PRESSURE ALONG THE MN/WI BORDER
WILL CONTINUE MOVING EAST. THUS MN SHOULD HAVE LIGHT SE WINDS
TONIGHT WHILE KEAU IS MOSTLY CALM OR LGT/VRBL. THERE IS A GOOD
RADIATIONAL COOLING SETUP LATE TONIGHT FOR KEAU AND KRNH... WITH
SOME CHANCE OF LIFR AT KEAU. NOT SURE ABOUT STC...WHERE LIGHT SE
WINDS COULD RESULT IN SOME RADIATIONAL FOG...WILL NEED TO WATCH
THIS AREA.

OTHERWISE...SE WINDS WILL BE STRENGTHENING THURSDAY MORNING AND
MID/HIGH CLOUDS CONTINUING TO INVADE THE AREA. SHOWERS WILL ENTER
WEST CENTRAL AND SOUTH CENTRAL MN THURSDAY MIDDAY BUT MAKE SLOW
PROGRESS TO THE EAST.

KMSP...GRADIENT WILL RESULT IN A LIGHT SE WIND TONIGHT...WHICH
SHOULD BE JUST ENOUGH TO KEEP ANY RADIATIONAL FOG AT BAY.
OTHERWISE JUST SOME MID-HIGH LEVEL CLOUDS WILL MOVE IN...WITH
SHOWERS NOT ANTICIPATED UNTIL LATE IN THE PERIOD THURSDAY
EVENING. WITH DEPARTURE OF SURFACE HIGH...SOUTHERLY WINDS WILL
PICK UP SOMEWHAT THURSDAY MIDDAY... WITH MAYBE SOME GUSTS AROUND
15 KTS.

/OUTLOOK FOR KMSP/
LATE THU NIGHT...VFR. CHC MVFR SHRA/TSRA. WIND S-SE 5-10 KTS.
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...TDK


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