Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 201743
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1243 PM CDT SUN APR 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 301 AM CDT SUN APR 20 2014

LATEST SURFACE ANALYSIS SHOWS A NICE SURFACE DEWPOINT GRADIENT
EXTENDING FROM SOUTHWEST MINNESOTA NORTHEAST INTO NORTHWEST
WISCONSIN. RAP 925-700MB LAYER MOISTURE CONVERGENCE SHOWS A DECENT
AREA OF DEEP MOISTURE CONVERGENCE ALONG THIS SAME GENERAL AXIS...
AND WE CONTINUE TO SEE SCATTERED SHRA DEVELOPING ALONG IT. THE RAP
SUGGESTS IT WILL REMAIN FAIRLY STATIONARY THROUGH AROUND 10Z THEN
SINK SOUTHEAST AND MAINLY JUST IMPACT THE FAR SOUTHEAST/EAST PORTION
OF THE FORECAST AREA. THE HRRR AND HOPWRF INDICATE A SIMILAR
EVOLUTION OF THINGS... WITH ACTIVITY DROPPING A BIT SOUTH AFTER 10Z
OR SO. HOWEVER... THE BAROCLINIC ZONE DOESN/T LOOK TO DROP TOO MUCH
FARTHER SOUTH THROUGH TONIGHT... SO ALTHOUGH WE SHOULD SEE ACTIVITY
GET SOUTH OF THE TWIN CITIES METRO THIS MORNING... IT DOESN/T LOOK
TO COMPLETELY EXIT THE FORECAST AREA ANYTIME SOON. IN FACT... THE
SHORTWAVE CURRENTLY EVIDENT OVER THE NORTHWEST CONUS IN WATER VAPOR
IMAGERY WILL MAKE ITS WAY EAST TOWARD THE AREA THIS EVENING. THIS
WILL MAINLY WORK TO GENERATE SOME PCPN WITH A SURFACE WAVE TO OUR
NORTH ALONG/NORTH OF THE CANADIAN BORDER TONIGHT INTO MONDAY
MORNING. HOWEVER... THE SOUTHERN EXTENSION OF THE UPPER WAVE LOOKS
LIKE IT WILL HELP GENERATE A WAVE ALONG THE STALLED BAROCLINIC ZONE
NEARLY THE SOUTHERN PORTION OF THE FORECAST AREA DURING THE
OVERNIGHT INTO EARLY MONDAY MORNING. THE GFS AND ECMWF BRING PCPN
FARTHER NORTH AGAIN LATER TONIGHT INTO MONDAY AS THIS OCCURS... AND
IT WOULD SEEM TO MAKE SENSE GIVEN THE ADDITIONAL FORCING AND AREA OF
ELEVATED INSTABILITY PROGGED TO MOVE THROUGH THE AREA ALONG/AHEAD OF
THE UPPER WAVE. SO... GENERALLY PUSHED POPS SOUTHWARD THROUGH THE
DAY TODAY... THEN LIFTED CHANCES NORTH AGAIN TONIGHT BEFORE
GRADUALLY SHIFTING THEM EASTWARD LATE TONIGHT AS WE FINALLY SEE SEE
SOME SURFACE RIDGING BEGIN TO MOVE IN FROM THE WEST.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 301 AM CDT SUN APR 20 2014

LONGER TERM CONCERNS INCLUDE FIRE WEATHER POTENTIAL MONDAY
AFTERNOON ACROSS THE WEST. THEN THE DEVELOPMENT OF THE WESTERN
CONUS TROUGH TOWARD MIDWEEK WITH THE THUNDER THREAT BUILDING EAST
INTO THE AREA WEDNESDAY INTO THURSDAY. ULTIMATE TIMING OF THE
TROUGH OVER THE AREA ALSO REMAINS A PROBLEM THROUGH THE REMAINDER
OF THE WEEK.

THE MODELS MAY HAVE SLOWED THE PROGRESSION OF THE FRONT ACROSS THE
REGION FOR MONDAY MORNING. WILL LEAVE A SMALL CHANCE OVER THE
EASTERN CWA THROUGH ABOUT MIDDAY MONDAY. THEN COOLER...DRIER AIR
MOVES INTO THE AREA WITH INCREASING NORTHWEST WINDS. WE SHOULD
SEE A GENERAL CLEARING SKY WITH PERHAPS SOME CUMULUS DEVELOPMENT
OVER THE CENTRAL AREA INTO MONDAY AFTERNOON AS THE COOLER AIR
MOVES IN. NORTHWEST WINDS 20-25 MPH ARE EXPECTED TO DEVELOP OVER
THE WEST INTO THE AFTERNOON AND RELATIVE HUMIDITY VALUES WILL DROP
OFF TO 25 TO 30 PERCENT OVER THE SOUTHWEST IN THE AFTERNOON. WILL
HAVE TO MONITOR THIS REGION DURING THE DAY AND SEE IF DEWPOINTS
DROP FURTHER. WILL CONTINUE TO MENTION THE DRIER HUMIDITY AND
WINDS IN THE FIRE WEATHER DISCUSSION.

PLEASANT WEATHER EXPECTED FOR TUESDAY WITH LIGHTER WINDS AS THE
HIGH DROPS OVER THE AREA. THE WESTERN CONUS TROUGH MOVES EAST WITH
INCREASING MOISTURE AND INSTABILITY INCREASING ESPECIALLY WEDNESDAY
NIGHT INTO THURSDAY OVER THE AREA. WILL LIKELY SEE SOME INITIAL WAA
SHOWERS MOVE IN TUESDAY NIGHT. THE LLJ INCREASING TO THE WEST OVER
THE EASTERN DAKOTAS LATER WEDNESDAY NIGHT AND SPILLS INTO FAR
WESTERN MN LATE. THEN THIS WILL TRANSLATE EAST INTO WEDNESDAY WITH
THE CONTINUED CHANCE OF SHOWERS. SOME ISOLATED THUNDER WILL WORK
INTO WESTERN AREAS MAINLY DURING THE DAY WEDNESDAY. WE DID REMOVE
THE THUNDER THREAT FARTHER TO THE EAST.

THE TROUGH AND ASSOCIATED SURFACE LOW DEVELOPS TO THE NORTHEAST
WEDNESDAY NIGHT INTO FRIDAY. THE LONGER TERM MODELS REMAIN IN
DISAGREEMENT ON HOW FAST THE TROUGH MOVES THE THE AREA. THE GFS
REMAINS THE SLOWEST AND WILL LIKELY TREND THAT WAY FOR NOW. WILL
CONTINUE THUNDER THREAT OVER THE ENTIRE CWA WEDNESDAY NIGHT AND
THURSDAY. SEVERE WEATHER THREAT WILL BE LIMITED AS IT APPEARS THE
REAL WARM SECTOR MAY BE HAVE SOME DIFFICULTY PENETRATING THE
COOLER/CLOUDY AREA OVER MUCH OF MINNESOTA. IT STILL APPEARS IT
WILL GET COLD ENOUGH FOR AT LEAST A RAIN/SNOW MIX DEVELOPING
FRIDAY NIGHT INTO SATURDAY AND AGAIN SATURDAY NIGHT INTO SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1242 PM CDT SUN APR 20 2014

TWO CONCERNS FOR THIS FORECAST CYCLE. THE FIRST IS SHRA/TSRA
CHANCES ALONG STALLED FRONTAL BOUNDARY FROM SW MN THROUGH NE WI
WHILE THE SECOND IS DENSE FOG LATE TONIGHT AND EARLY MONDAY ALONG
AFOREMENTIONED BOUNDARY. VARIOUS 12Z WRF SOLUTIONS WOULD POINT TO
THUNDERSTORM DEVELOPMENT BY EARLY THIS EVENING NEAR THE IA/MN
BORDER ON EASTWARD INTO WI. THIS WOULD BE WELL SOUTH OF KEAU WITH
ONLY A FEW SHOWERS INDICATED BETWEEN KRWF-KMSP AND KEAU. LATEST
WRF TRENDS HAVE ALSO BACKED AWAY FROM OVERNIGHT ACTIVITY ARRIVING
FROM THE WEST. WITH LESS CLOUDS AND SHOWERS THERE WILL LIKELY BE
MORE OF A RISK OF DENSE FOG LATE TONIGHT AND EARLY MONDAY...
ESPECIALLY FOR KEAU WHERE A 1/4SM FG IS NOW IN PLACE FROM 09Z-13Z.
NW WINDS WILL INCREASE SIGNIFICANTLY MONDAY MORNING FROM KAXN TO
KRWF IN THE WAKE OF A COLD FRONT. SPEEDS WILL APPROACH 20 KNOTS BY
LATE MORNING WITH GUSTS NEAR 30 KNOTS. INCREASING NW WINDS FOR THE
EASTERN TAF SITES BY EARLY IN THE AFTERNOON.

KMSP...IT APPEARS THAT ANY SIGNIFICANT SHRA/TSRA ACTIVITY WILL BE
WELL SOUTH AND SE OF THE AIRFIELD LATE THIS AFTERNOON AND EARLY
THIS EVENING. MVFR VSBY POSSIBLE LATE IN THE NIGHT BEFORE WINDS
SHIFT TO THE NW SHORTLY AFTER 12Z. SPEEDS INCREASING TO NEAR 20
KNOTS FOR MONDAY AFTERNOON WITH A FEW GUSTS REACHING 30 KNOTS.

/OUTLOOK FOR KMSP/

MON NGT...VFR. NW 10-15 KTS.
TUE...VFR. NW WIND LESS THAN 10KTS BECOMING VRBL LESS THAN 5KTS.
WED-THU...MVFR CIGS AND VSBYS WITH RAIN LIKELY. IFR CONDITIONS
POSSIBLE ALONG WITH A CHC OF TSTMS. SE WIND 10-20 KTS BECOMING SW.

&&

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

$$

UPDATE...
SHORT TERM...MPX
LONG TERM...DWE
AVIATION...RAH






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