Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 302015
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
315 PM CDT THU APR 30 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 310 PM CDT THU APR 30 2015

A SURFACE RIDGE EXTENDED SOUTHEAST ACROSS THE GREAT LAKES AND INTO
WC WI AND EC MN WHICH KEPT WINDS LIGHT FROM THE NE/EAST TODAY. A
SURFACE TROUGH IN THE WESTERN DAKOTAS HAS ALLOWED THE PRESSURE
GRADIENT IN FAR WESTERN MN TO STRENGTHEN OVER THE PAST FEW HRS. AS
DAYTIME MIXING OCCURRED... RH FIELDS LOWERED INTO THE TEENS IN FAR
WC MN. THESE LOWER DEW PTS AND RH FIELDS IN THE BOUNDARY LAYER
WILL TAKE SOME TIME TO MOISTEN TONIGHT. THEREFORE AS A WEATHER
DISTURBANCE MOVES EASTWARD ACROSS THE DAKOTAS /GENERATING
OCCASIONAL SHRA/ SOME OF THE ACTIVITY WILL LIKELY DISSIPATE
BEFORE DEEPER MOISTURE BEHIND THE WEAKENING SURFACE TROUGH MOVES
INTO OUR REGION AFTER MIDNIGHT.

WILL CONTINUE THE LIKELY/CATEGORICAL POPS IN WESTERN MN AFT
MIDNIGHT. THIS IS MAINLY DUE TO THE STRENGTH OF THE SHRTWV NOTED
ON WV IMAGERY IN MT/WY THIS AFTN AND ITS ASSOCIATED JET STREAK
WHICH WILL MOVE ACROSS MN LATE TONIGHT. THE MAIN DILEMMA FOR
FRIDAY IS HOW FAR EAST ACROSS MN DOES THIS AREA OF SHRA
CONTINUE...OR DOES IT WEAKEN AS THE UPPER LEVEL SUPPORT MOVES OUT
OF THE AREA. MOST OF THE DEEPER MOISTURE RESIDES BEHIND THE
WEAKENING TROUGH LATE TONIGHT/EARLY FRIDAY...SO INITIALLY THE
DEPTH OF THE ATMOSPHERIC MOISTURE IN EASTERN MN WILL BE LIMITED.
SO WITH THE UPPER LEVEL SUPPORT ALSO WEAKENING...HAVE TRENDED
DOWNWARD ON POPS BY 18Z FROM WEST TO EAST. THERE WILL BE SCATTERED
SHRA IN SC/EC MN DURING THE MORNING...BUT THE ACTIVITY WILL LIKELY
WEAKEN WITH THE MAIN ACTIVITY FOCUSING SOUTH INTO IOWA BY THE AFTN.
WITH THE AMT OF CLOUD COVER AND ASSOCIATED -SHRA POSSIBLE...KEPT
TEMPS A FEW DEGREES COOLER IN EC/SC MN AND WC WI. WC/SW MN WILL
LIKELY RISE BACK INTO THE LOW TO MID 70S BY THE AFTN.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 417 AM CDT THU APR 30 2015

AS MENTIONED ABOVE...THE BAND OF SHOWERS WILL BE ONGOING EARLY
FRIDAY MORNING FROM SOUTHWEST TO NORTH CENTRAL MN. THE COMBINATION
OF DRY AIR AND QUICKLY WEAKENING FORCING WILL ALLOW FOR A
DISSIPATION TREND AS THE LINE PUSHES EAST AND THE MORNING
PROGRESSES. BEGAN WITH CATEGORICAL POPS FROM RWF TO LXL AT
12Z...WITH ONLY SLIGHT CHC BY EARLY AFTERNOON ACROSS WRN WI. TEMPS
FRIDAY WILL BE SOMEWHAT TRICKY OVER THE EAST WHERE CLOUDS AND
POTENTIAL SHOWERS WILL LINGER THE LONGEST...AND THUS THERE IS
SOME QUESTION HOW FAR EAST THE WARM FRONT WILL CLEAR. WRN MN
SHOULD SEE A GOOD AMOUNT OF SUN BY AFTERNOON AND WILL BE FIRMLY IN
THE WARM SECTOR WITH HIGHS IN THE UPPER 70S. UNDER THE CLOUDS
FURTHER EAST...TEMPS MAY STRUGGLE TO REACH THE UPPER 60S.

THE WARM FRONT WILL BE WELL TO THE EAST SATURDAY. 925 MB TEMPS
RISE THROUGH THE DAY TO +18C OVER WRN WI AND +22C NEAR THE SODAK
BORDER SO SHOULD SEE HIGHS IN THE UPPER 70S TO MID 80S
RESPECTIVELY. BELIEVE GUIDANCE IS TOO COOL AS IT HAS BEEN MOST OF
THE SPRING. BIAS CORRECTED GRIDS WERE THE BEST BET FOR SATURDAY.
MIXING TO 750 MB DOES NOT BRING DEW POINTS QUITE AS LOW AS THOUGHT
YESTERDAY. STILL LOOKING AT MIN RH VALUES LESS THAN 30 PERCENT...
BUT WIND WILL BE LIGHT ENOUGH THAT FIRE WEATHER SHOULD NOT BE A
BIG CONCERN.

A TROUGH BEGINS TO DIG OVER THE NORTHERN ROCKIES AND ALONG THE
INTERNATIONAL BORDER SATURDAY NIGHT. A COLD FRONT WILL DROP SOUTH
SUNDAY. THERE ARE STILL CONCERNS OF HOW QUICKLY IT WILL PUSH
THROUGH THE AREA BUT FOR NOW THE NAM AND GFS ARE IN RATHER GOOD
AGREEMENT WITH NOT ONLY TIMING...BUT THE MAGNITUDE OF THE
PRE-FRONTAL THERMAL RIDGE. BOTH MODELS BRING +20C AT 850 MB INTO
SWRN MN AND +20 TO +25C AT 925 MB UP INTO NWRN WI. ASSUMING FULL
MIXING POTENTIAL AND ONLY A FEW HIGH CLOUDS...THIS WOULD BOOST
HIGHS INTO 85 TO 90 DEGREE RANGE. EVEN THE NOTORIOUSLY COOL 2M
TEMPS FROM THE GFS REACH THE MID 80S. DID RAISE HIGHS 3 TO 5
DEGREES ACROSS SRN MN INTO WRN WI...BUT DID NOT FEEL COMFORTABLE
GOING HIGHER YET UNTIL CONFIDENCE INCREASES ON TIMING OF THE FROPA
AND CONVECTIVE INITIATION...AND HIGH CLOUD COVERAGE.

CONVECTION SHOULD DEVELOP BY EARLY AFTERNOON ACROSS WRN AND NRN MN
BEFORE GROWING MORE WIDESPREAD AND SINKING SOUTH THROUGH THE
EVENING. LACK OF HIGH THETAE AIR WILL LIMIT INSTABILITY AND THE
LACK OF SHEAR WILL KEEP SEVERE CHANCES QUITE LOW.

THE SURFACE FRONT WON/T GO TOO FAR FOR EARLY NEXT WEEK BEFORE
LIFTING BACK NORTH AROUND MIDWEEK AS A LARGE EASTERN TROPICAL
PACIFIC SYSTEM EMERGES ONTO THE CENTRAL PLAINS. LONG RANGE MODELS
ARE PRETTY CONSISTENT IN SHOWING MULTIPLE ROUNDS OF SHOWERS AND
THUNDERSTORMS FOR MID TO LATE NEXT WEEK. WPC NOTES CLUSTERING OF
THIS SYSTEM IS WELL ABOVE AVERAGE GIVEN ITS ORIGIN AND SIZE...AND
FORECAST TIME FRAME. THUS...POPS HAVE BEEN INCREASED TO 50 PERCENT
ON DAYS 6/7.

.FIRE WEATHER...
ISSUED AT 417 AM CDT THU APR 30 2015

AS A COLD FRONT PUSHES THROUGH THE DAKOTAS THIS AFTERNOON...SSE
WINDS IN WEST CENTRAL MN WILL INCREASE TO BETWEEN 10 AND 20 MPH.
THIS WILL BE COINCIDENT WITH HUMIDITIES FALLING TO BETWEEN 15 AND 25
PERCENT. THOUGH SUSTAINED WINDS ARE EXPECTED TO REMAIN BELOW THE 20
MPH RED FLAG WARNING THRESHOLD...THE VERY DRY HUMIDITIES COMBINED
WITH THESE WINDS WILL LEAD TO ELEVATED FIRE WEATHER CONDITIONS OUT
IN WEST CENTRAL MN. AT THIS POINT...PLAN ON DOING NOTHING MORE THAN
ADDING A HEADLINE TO THE FIRE WEATHER PLANNING FORECAST TO HIGHLIGHT
THESE ELEVATED FIRE WEATHER CONDITIONS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1230 PM CDT THU APR 30 2015

NO AVIATION CONCERNS WITH ONLY A SMALL CHC OF MVFR VSBYS IN -SHRA
FOR LATER TONIGHT/EARLY FRIDAY MORNING IN WC/CENTRAL MN.
OTHERWISE...SE/E/NE WINDS WILL BECOME MORE S/SE OVERNIGHT AND
SHIFT TO THE SW FRIDAY MORNING.

KMSP...

NO AVIATION CONCERNS THRU FRIDAY MORNING. WINDS WILL BE GENERALLY
FROM THE NE THIS AFTN...E/SE TONIGHT...AND S/SW BY FRIDAY MORNING.

/OUTLOOK FOR KMSP/

SAT...VFR. WINDS SSW 10 KTS.
SUN...VFR. -TSRA/MVFR LIKELY AFTERNOON/EVENING. WINDS S 5-10
KTS...SHIFTING TO THE NW/N BY THE AFTN AND INCREASING.
MON...POSSIBLE MVFR CIGS EARLY. WINDS NE 10 KTS.


&&

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

$$

SHORT TERM...JLT
LONG TERM...BORGHOFF
AVIATION...JLT


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