Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 300917
AFDMPX

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

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 417 AM CDT THU APR 30 2015

BATCH OF CLOUDS OVER ERN MN THIS MORNING SITS ON THE WARM SIDE OF A
NORTHERLY JET STREAK THAT IS WORKING DOWN THROUGH WI TO THE WEST OF
AN UPPER LOW CENTERED NEAR MANISTEE MICHIGAN. THESE CLOUDS ARE ALL
BASED UP BETWEEN 10K AND 12K FT...SO NOT EXPECTING ANY PRECIPITATION
WITH THEM AS THEY DISSIPATE THROUGH THE MORNING. FARTHER WEST...AN
H5 RIDGE AXIS EXTENDS FROM COLORADO TO NW MN WITH A SHORTWAVE TROUGH
NOW WORKING ACROSS THE NORTHERN ROCKIES. AS WE GO THROUGH THE
DAY...THIS UPPER RIDGE WILL MOVE ACROSS MN...WHILE THE ROCKIES
TROUGH GETS HERE LATE TONIGHT.

FOR TODAY...NOT MUCH IS EXPECTED TO HAPPEN WITH THE UPPER RIDGE
MOVING OVERHEAD LEADING TO MOSTLY SUNNY SKIES. WRN WI WILL STILL BE
UNDER THE INFLUENCE OF THE GREAT LAKES LOW...WITH H85 TEMPS SIMILAR
TO YESTERDAY...SO EXPECTED HIGHS TODAY TO BE SIMILAR TO WHAT WAS
SEEN YESTERDAY FROM ERN MN INTO WRN WI. IN WRN MN...A 925-850
THERMAL RIDGE WILL MOVE IN WITH THE H5 RIDGE...WITH H85 TEMPS UP
OVER 10C EXPECTED BY THE AFTERNOON OUT BY THE SODAK BORDER. THIS
WILL TRANSLATE INTO HIGHS BEING 5 TO 8 DEGREES WARMER THAN YESTERDAY
OUT IN WESTERN MN. FOR HIGHS TODAY...STUCK CLOSE TO A BLEND OF THE
BIAS CORRECTED GUIDANCE. SEE FIRE WEATHER SECTION FOR MORE
INFORMATION ON THE ELEVATED FIRE WEATHER CONCERNS EXPECTED OUT WEST
THIS AFTERNOON.

POSITIVE VORTICITY ADVECTION COMBINED WITH FGEN IN THE H7-H6 LAYER
WILL LEAD TO A BAND OF SHOWERS MOVING ACROSS THE DAKOTAS AND INTO
WRN MN TONIGHT. WITH THE RIDGING TO THE EAST ALONG WITH THE DRY LOW
LEVEL AIR THIS BAND OF SHOWERS WILL BE MOVING INTO...DID FAVOR THE
POP FORECAST TO A BLEND OF THE SLOWER ECMWF/GFS/NAM AS OPPOSED TO
THE FASTER SREF AND ASSORTED CAMS. THE POP BLEND USED RESULTED IN
RAIN CHANCES GETTING ABOUT AS FAR EAST AS A ST. JAMES TO ST. CLOUD
LINE BY 12Z FRIDAY WHILE AN SREF/CAMS SOLUTION WOULD HAVE RAIN
ALMOST TO THE WI BORDER BY 12Z FRIDAY.

.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
PREFRONTAL 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1239 AM CDT THU APR 30 2015

ONLY CHANGE MADE TO THE TAFS WAS TO UP SKY COVER AROUND 10K FEET
FOR THE REST OF TONIGHT AT STC/MSP/RNH TO ACCOUNT FOR BAND OF
CLOUDS COMING DOWN FROM NE MN. OTHERWISE...BAND OF SHOWERS WILL BE
MOVING ACROSS THE DAKOTAS LATE IN THE TAF PERIOD...BUT WILL NOT
MOVE INTO AXN/RWF UNTIL AFTER 6Z AND MSP UNTIL AFTER 12Z ON
FRIDAY.

KMSP...HIGH PRESSURE WILL REMAIN IN CONTROL. SOME QUESTION AS TO
WIND DIRECTION THROUGH THE DAY THURSDAY WITH THE RIDGE MOVING
OVERHEAD...BUT WITH SPEEDS UNDER 7 KTS...SHOULD NOT BE OF
SIGNIFICANT IMPACT TO OPERATIONS.

/OUTLOOK FOR KMSP/
FRI...VFR. CHANCE -SHRA. WINDS SW 5-10 KTS.
SAT...VFR. WINDS SW 7-10 KTS.
SUN...VFR. -TSRA/MVFR LIKELY AFTERNOON/EVENING. WINDS S 5-10 KTS.

&&

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

$$

SHORT TERM...MPG
LONG TERM...BORGHOFF
AVIATION...MPG



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