Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 130400
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1100 PM CDT FRI SEP 12 2014

.UPDATED FOR 06Z AVIATION DISCUSSION...
ISSUED AT 1055 PM CDT FRI SEP 12 2014

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 302 PM CDT FRI SEP 12 2014

COLD POOL ALOFT...CHARACTERIZED BY H5 TEMPS OF -26C...HAS ALLOWED
FOR SCATTERED SHOWERS AND MOSTLY CLOUDY SKIES TO DEVELOP. JUST ABOUT
ALL OF THIS IS DIURNALLY DRIVEN...WHICH MEANS AFTER SUNSET...WE WILL
QUICKLY SEE SKIES CLEAR OUT. THROW IN THE LIGHT WINDS AND WE GET
WHAT THE MODELS HAVE BEEN SHOWING FOR DAYS...A VERY CHILLY NIGHT
TONIGHT. ONLY MINOR CHANGE MADE TO THE LOWS TONIGHT WAS RAISE LOWS
IN THE URBAN CORE OF THE TWIN CITIES UP INTO THE LOW 40S. THE REASON
FOR THIS IS THAT THE 4 CIPS MEMBERS FROM THE 00Z NAM THAT OCCURRED
WITHIN A FEW DAYS OF SEP 13 ALL HAD LOWS BETWEEN 41 AND 44 AT
MSP...SO SIMPLY WENT WITH SOMETHING CLOSER TO THE MET/LAV
NUMBERS...WITH LOWER 40 LOWS. EVERYWHERE ELSE...THE CLEAR SKIES WILL
ALLOW TEMPS TO FALL BACK INTO THE LOWER/MID 30S. ONLY POTENTIAL
LIMITING FACTOR FOR FROST WILL BE IN WEST CENTRAL MN...WHERE LIGHT
SW WINDS WILL BEGIN TO DEVELOP OVERNIGHT. ONLY COUNTY THAT CURRENTLY
DOES NOT HAVE ANY PART OF THE COUNTY WITH LOWS FORECAST TO GET TO 36
OR LESS /CRITERIA FOR FROST ADVISORY/ IS RAMSEY...BUT FOR MAP
AESTHETIC REASONS...INCLUDED ALL COUNTIES IN THE FROST ADVY. WILL
LIKELY SEE TEMPS BETWEEN 30 AND 32 OUT AROUND RUSK COUNTY...ALONG
WITH POCKETS IN CENTRAL MN...BUT AREAL COVERAGE OF LOWS TO THAT
LEVEL LOOKING TO BE LIMITED...ALONG WITH COLLABORATION WITH
DLH/ARX...WE ALL FELT THE FROST ADVY WAS ENOUGH FOR TONIGHT.

FOR SATURDAY...WE WILL SEE A STRONG WAVE MOVE ACROSS THE
INTERNATIONAL BORDER WITHIN THE ZONAL FLOW ACROSS THE CENTRAL NRN
CONUS. THIS WILL GIVE US INCREASING MID AND HIGH CLOUDS THROUGH THE
DAY. BUFR SOUNDINGS SHOW US MIXING TO AROUND H8 SATURDAY...AND
MIXING TO THAT LEVEL SATURDAY OFF THE NAM YIELDED WHAT WE ALREADY
HAD GOING FOR HIGHS...MID 60S SOUTHWEST AND UPPER 50S NORTHEAST...SO
RELATIVELY LITTLE CHANGES WERE MADE TO THE FORECAST FOR SATURDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 302 PM CDT FRI SEP 12 2014

NOTHING REALLY MUCH OF INTEREST WEATHER WISE IN THE LONG TERM
UNTIL THE TAIL END OF THE PERIOD...WITH A COUPLE OF MAINLY DRY
COLD FRONTS WORKING ACROSS THE AREA SUN/SUN NIGHT AND AGAIN ON
WED...WITH A FRONT OF MORE SIGNIFICANCE LOOKING TO ARRIVE FRI/NEXT
WEEKEND.

THE STRONG SHORT WAVE MENTIONED IN THE SHORT TERM FOR SATURDAY
WILL DRIVE A WEAK AND MOISTURE STARVED FRONT INTO THE AREA
SATURDAY NIGHT. AS THIS FRONT MOVES ACROSS THE AREA
SUNDAY...MODELS ARE SIMILAR WITH DEVELOPING LIGHT RAIN WITHIN A
ZONE OF STRONG MID LEVEL FGEN THAT DEVELOPS WITHIN THE STRONG PV
ADVECTION AHEAD OF A SECONDARY WAVE THAT WILL MOVE INTO SRN MN BY
MONDAY MORNING. AGAIN...DRY LOW LEVEL AIR LOOKS TO BE A LIMITING
FACTOR...BUT JUST ABOUT ALL GUIDANCE SPITS OUT SOME LIGHT QPF DOWN
ALONG THE I-90 CORRIDOR...WHICH IS WHERE THE HIGHEST POPS WERE
CONTAINED TO.

BEHIND THIS WAVE...WE WILL GET INTO NW FLOW ALOFT THROUGH
THURSDAY. WE WILL SEE A BACK-DOOR COLD FRONT MOVE SOUTHWEST ACROSS
THE AREA WEDNESDAY AS A COOL/DRY HIGH MOVES INTO THE GREAT LAKES.
THIS FRONT WILL HAVE EVEN LESS MOISTURE THAN THE SUNDAY FRONT TO
WORK WITH AND WILL BE LACKING THE STRONG UPPER DYNAMICS AS
WELL...SO FEEL CONFIDENT IN THIS FRONT COMING THROUGH DRY. IT WILL
SIMPLY GIVE US A REINFORCING SHOT OF COOL/DRY AIR FROM THE
NE...PUTTING A MOMENTARY PAUSE IN OUR GENERAL WARMING TREND NEXT
WEEK.

BY THE END OF NEXT WEEK...THE FLOW WILL BECOME LESS AMPLIFIED AS
THE WRN RIDGE FLATTENS OUT AND SHIFTS EAST INTO THE PLAINS. THERE
ARE YOUR EXPECTED TIMING DIFFERENCES WITH THE GFS/ECMWF THIS FAR
OUT...WITH THE GFS SHOWING SUFFICIENT MOISTURE TRANSPORT WORKING
INTO THE AREA FRIDAY TO BRING IN A THREAT FOR PRECIP...WHILE THE
ECMWF WAITS UNTIL FRIDAY NIGHT. GIVEN THE SPREAD...BLENDED POP
FORECAST RESULTED 30 POPS GETTING INTRODUCED TO THE FORECAST
FRIDAY. THIS SYSTEM WILL HAVE SUFFICIENT TEMP/MOISTURE RETURN WITH
IT TO BRING BACK THE THREAT FOR THUNDERSTORMS...SO ALLOWED THAT
WORDING TO RETURN TO THE FORECAST AS WELL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1055 PM CDT FRI SEP 12 2014

VFR CONDITIONS EXCEPT AT KEAU WHERE DENSE FOR IS EXPECTED TO
PERSIST OVERNIGHT. PATCHY FOG IS POSSIBLE AT KSTC AND KRNH...BUT
CONFIDENCE IS TO LOW TO INCLUDE SUB-VFR CONDITIONS IN THE TAFS. ON
SATURDAY SSW WINDS WILL DEVELOP WITH AFTERNOON GUSTS 15-20KTS.

KMSP...
VFR CONDITIONS THROUGHOUT. LIGHT WINDS WILL GRADUALLY BECOME
SSW...WITH AFTERNOON GUSTS TAPERING OFF AFTER SUNSET SATURDAY
EVENING.

/OUTLOOK FOR KMSP/
SUN...VFR. WINDS W AT 10G15KTS.
MON...VFR. WINDS NW AT 10G15KTS.
TUE...VFR. WINDS W AT 10KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FROST ADVISORY FROM 3 AM TO 8 AM CDT SATURDAY FOR MNZ041>045-
     047>070-073>078-082>085-091>093.

WI...FROST ADVISORY FROM 3 AM TO 8 AM CDT SATURDAY FOR WIZ014>016-
     023>028.

&&

$$

SHORT TERM...MPG
LONG TERM...MPG
AVIATION...JRB






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