Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 220412
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1112 PM CDT MON APR 21 2014

.UPDATE...
ISSUED AT 1106 PM CDT MON APR 21 2014

UPDATED TO INCLUDE 06Z AVIATION DISCUSSION.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 343 PM CDT MON APR 21 2014

THE GUSTY NORTHWEST WINDS ACROSS THE AREA THIS AFTERNOON WILL
DIMINISH SIGNIFICANTLY DURING THE EVENING AS HIGH PRESSURE SETTLES
IN FROM THE DAKOTAS. LOWS WILL DIP INTO THE UPPER 20S ACROSS
CENTRAL MN AND ADJOINING AREAS OF WEST CENTRAL WI WITH MIDDLE TO
UPPER 30S TO THE SOUTH.

TUESDAY WILL BE A FINE DAY WEATHER-WISE WITH THE HIGH OVERHEAD.
WINDS WILL BE MORE NORTHERLY WITH SPEEDS 10 MPH OR LESS. AFTERNOON
HUMIDITY READINGS WILL DIP INTO THE 30 TO 35 PERCENT RANGE. HIGHS
ON TUESDAY WERE ALMOST EXCLUSIVELY MIX-DOWN FROM 825MB OFF THE
NAM ALONG WITH A SLIGHT SUPER. THIS YIELDED READINGS FROM AROUND
60 IN THE MN RIVER VALLEY TO THE LOWER 50S AROUND LADYSMITH.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 343 PM CDT MON APR 21 2014

NO MAJOR CHANGES TO THE EXTENDED...BESIDES RAISING POPS IN THE
WEDNESDAY-THURSDAY TIME FRAME GIVEN THE CONSISTENT SIGNAL FOR
PRECIP AND BETTER MODEL CONSENSUS /ESPECIALLY WITH RESPECT TO THE
DEVELOPING SURFACE LOW MOVING NEAR THE FORECAST AREA WEDNESDAY
NIGHT INTO THURSDAY/.

THE MAIN PRECIP EVENT HAS SHIFTED A BIT LATER IN TIME AND WILL
MOST LIKELY OCCUR LATE WEDNESDAY NIGHT AND THURSDAY MORNING WITH
ADVANCING 600-800MB FGEN AND WIDESPREAD OMEGA WITH AN ADVANCING
SURFACE CYCLONE FROM THE CENTRAL PLAINS. THE ISENTROPIC LIFT WITH
THE WARM ADVECTION DURING THE DAY ON WEDNESDAY PRECEDING THE
CYCLONE SHOULD PROVIDE WIDESPREAD RAIN...BUT WITH LIGHT QPF
AMOUNTS. ONLY THE 21.12Z GFS HAS MORE OF A CONVECTIVELY BASED QPF
BULLSEYE IN WEST CENTRAL MN. AS FAR AS THE PRECIP WEDNESDAY NIGHT
INTO THURSDAY...WE ARE MUCH HAPPIER WITH THE MODE AGREEMENT TODAY
AS COMPARED TO YESTERDAY. THERE ARE STILL SOME SLIGHT TIMING
ISSUES AND THE 21.12Z ECMWF IS A BIT FARTHER SOUTH WITH THE
SOUTHERN STREAM LOW...BUT MODEL CONSENSUS NOW IS FOCUSING THE
HEAVIEST RAIN ALONG AN AXIS FROM WESTERN IA...TO SOUTH
CENTRAL/SOUTHEAST MN...AND INTO WESTERN WI. THE GFS REMAINS A BIT
FARTHER NORTH AND WOULD HAVE THE AXIS OF HEAVIER PRECIP AS FAR
NORTH AS THE TWIN CITIES METRO. WE ARE DISCOUNTING THE GEM AS AN
EXTREME NORTHERN OUTLIER.

THE RAIN MOVES OUT OF THE AREA THURSDAY AFTERNOON JUST AS A
SECOND COLD FRONT WORKS THROUGH THE AREA FRIDAY WITH MUCH COOLER
CONDITIONS TO FOLLOW. WITH DRY NORTHEAST TO EASTERLY FLOW SETTING
UP WITH HIGH PRESSURE TO THE NORTH AND STRENGTHENING MID LEVEL
RIDGE...WE PROBABLY SHOULD HAVE BEEN MORE AGGRESSIVE AT CLEARING
OUT PRECIP CHANCES FRIDAY THROUGH SUNDAY. THERE IS AN ADVANCING
UPPER LOW LATE IN THE WEEKEND BUT MUCH OF THE FORCING REMAINS TO
THE SOUTH OF THE FORECAST AREA. WITH COOL EAST TO NORTHEAST
FLOW...KEPT TEMPERATURES BELOW NORMAL THROUGH THE END OF THE
FORECAST PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1106 PM CDT MON APR 21 2014

VFR THROUGHOUT THIS SET. WIND WILL REMAIN MAINLY NW WITH SPEEDS
5-10 KT OVERNIGHT INTO TMRW MRNG...THEN GRADUALLY SHIFT TO N AND
NE THRU THE DAY...CONTINUING TO VEER TO E AND SE THROUGH THE
EVENING. HIGH CLOUDS WILL START TO STREAM IN TMRW AFTN...BECOMING
A HIGH CEILING FOR THE MN SITES BY TMRW EVENING...BUT NO
SIGNIFICANT IMPACTS EXPECTED AND DRY WX THRU 23/06Z.

KMSP...VFR. WINDS REMAIN NW OVERNIGHT THRU DAYBREAK THEN BECOME
MORE NE BY MIDDAY TMRW...THEN CONTINUE TO VEER TO E AND SE LATE
TMRW AFTN THRU TMRW EVE. SPEEDS GENERALLY IN THE 5-10 KT RANGE. FEW-
SCT HIGH CLOUDS LATE DAY TMRW BECOME A HIGH CEILING TMRW EVENING.

/OUTLOOK FOR KMSP/
WED...MAINLY VFR. MVFR CONDS PSBL IN -RA. SE WIND 10-20 KT.
WED NGT...MVFR CONDS LIKELY IN -RA WITH IFR PSBL. SE WIND 15-20
KT.
THU...MVFR CONDS LIKELY EARLY WITH -RA. S WIND 10-20 KT SHIFTING
W.
THU NGT...VFR. W WIND 5-15 KT.
FRI...MAINLY VFR. MVFR CONDS PSBL WITH A CHC -RA. W WIND 5-15 KT
BCMG NW.

&&

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

$$

UPDATE...JPC
SHORT TERM...RAH
LONG TERM...CLF
AVIATION...JPC






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