Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 152055
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
355 PM CDT WED APR 15 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 352 PM CDT WED APR 15 2015

MAIN CONCERN IN THE SHORT TERM IS THE DANGEROUSLY DRY CONDITIONS
ACROSS THE UPPER MIDWEST THIS AFTERNOON WITH RESPECT TO FIRE
WEATHER. THE CAUSE STEMS FROM A TROUGH OF LOW PRESSURE OVER THE
HIGH PLAINS RESULTING IN SOUTH SOUTHEASTERLY WINDS OVER MN/WI. DEW
POINTS HAVE MIXED INO THE TEENS AT SEVERAL LOCATIONS.

A WEAK SHORTWAVE WAS MOVING UP FROM THE MISSOURI RIVER VALLEY WAS
RESPONSIBLE FOR AN AREA OF ENHANCED CLOUDINESS AND LIGHT PRECIP
OVER NORTHWEST IOWA. HOWEVER...GIVEN THE DRY BOUNDARY LAYER WILL
STRUGGLE TO HAVE ANY MEASURABLE PRECIP REACH THE GROUND ACROSS THE
WESTERN CWA.

FRIDAY WILL BE WARM AS WELL...BUT MID LEVEL CLOUDS WILL KEEP RH
VALUES CLOSER TO 30 OR 40 PERCENT. THE SURFACE PRESSURE GRADIENT
WILL ALSO RELAX...WITH WINDS AROUND 5 TO 10 MPH.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 352 PM CDT WED APR 15 2015

FAIRLY SUBSTANTIAL PATTERN CHANGE AT THE END OF THE WEEK WILL TAKE
PLACE AS WE TRANSITION FROM A WARM...DRY PATTERN TO A
COOL...CLOUDY...WETTER PATTERN. TEMPERATURES WILL BE BELOW THE
SEASONAL AVERAGE TO START NEXT WEEK.

THE TWO MAIN PLAYERS IN THE EXTENDED ARE 1) AN UPPER LEVEL LOW OVER
THE GREAT BASIN AND 2) A SHORTWAVE IN THE GULF OF ALASKA. OVER THE
NEXT SEVERAL DAYS...THE AFOREMENTIONED LOW WILL BECOME CUT OFF FROM
THE NORTHERN STREAM AND MEANDER ACROSS THE DESERT SOUTHWEST. THIS
WILL BE THE FOCUS FOR SOAKING RAINS ON THE FOOT HILLS OF COLORADO
AND WYOMING...WITH SNOW IN THE HIGHER ELEVATIONS. AS THE LATENT HEAT
FROM THIS PRECIPITATION GRADUALLY WARM THE MID LEVELS OF THE
ATMOSPHERE...THE POTENTIAL VORTICITY WILL ERODE OVER TIME...AND THE
UPPER LEVEL LOW WILL WEAKEN AND FILL. THIS MEANDERING UPPER LEVEL
LOW WILL GENERATE CONTINUED ROUNDS OF SHOWERS AND
THUNDERSTORMS...BUT THE NORTHEASTWARD EXTENT REMAINS UNCERTAIN DUE
TO THE VARIABILITY WITH THE TIMING OF THE DOWNSTREAM PROGRESSION OF
THIS WAVE.

MEANWHILE...THE NORTHERN STREAM SHORTWAVE WILL RACE ACROSS SOUTHERN
CANADA AND DIVE SOUTHEAST TOWARD THE UPPER MIDWEST. TIMING ON THIS
WAVE IS MORE CERTAIN GIVEN THE STRENGTH OF THE UPPER LEVEL FLOW
WITHIN WHICH IT RESIDES. THIS WAVE WILL BRING MUCH COOLER
TEMPERATURES...AND CARVE OUT AN UPPER LEVEL LOW ACROSS THE GREAT
LAKES. THIS WOULD BRING SUB-ZERO H850 TEMPS ACROSS THE UPPER
MIDWEST...LEADING TO OVERCAST SKIES AND TEMPERATURES AROUND 10
DEGREES BELOW THE SEASONAL AVERAGE FOR MID TO LATE APRIL. A FEW
SNOWFLAKES COULD BE MIXED IN WITH THE RAIN SHOWERS...BUT THE RATE
WILL NOT BE ENOUGH TO CAUSE ACCUMULATION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 100 PM CDT WED APR 15 2015

VFR EXPECTED WITH BREEZY SOUTHEAST WINDS THROUGH THE AFTERNON.
CEILINGS LOWER TOWARD THE END OF THE TAF PERIOD.

KMSP...
VFR WITH SLOWLY VEERING WINDS TONIGHT.

/OUTLOOK FOR KMSP/
FRI...VFR. ISOLD -SHRA POSSIBLE. WINDS NW 10-15 KTS.
SAT...VFR. SHRA POSSIBLE. WINDS NE 5-10 KTS.

.FIRE WEATHER...
ISSUED AT 352 PM CDT WED APR 15 2015

CRITICAL FIRE WEATHER CONDITIONS CONTINUE THIS
AFTERNOON ACROSS ALL OF SOUTHERN MN AND WEST CENTRAL WI.  AN
EXTREMELY DRY AIR MASS IN PLACE OVER THE WESTERN GREAT LAKES
CONTINUES TO INFLUENCE OUR LOCAL WEATHER...WITH DEW POINTS CRASHING
INTO THE LOW 20S...AND AIR TEMPERATURES IN THE UPPER 60S AND LOWER
70S.  RH VALUES IN THE TEENS ARE COMMON THIS AFTERNOON...WITH GUSTS
RANGING FROM 25 TO 35 MPH CREATING CRITICAL FIRE WEATHER
CONDITIONS...WHICH WILL CONTINUE INTO THE EVENING.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR MNZ041>045-
     047>070-073>078-082>085-091>093.

WI...RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR WIZ014>016-
     023>028.

&&

$$

SHORT TERM...JRB
LONG TERM...JRB
AVIATION...CLF



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