Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 301043
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
543 AM CDT THU OCT 30 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT THU OCT 30 2014

ONE AREA OF DECREASING AREAL COVERAGE OF -RA WAS ACROSS SW MN AS OF
230 AM WHICH PRODUCED LOCALLY A TENTH OF AN INCH OF RAINFALL AT
MADISON. THIS AREA WAS ASSOCIATED WITH A DEPARTING SHRTWV MOVING
QUICKLY SE ACROSS SE SD. INITIAL DRY AIR MASS ACROSS SC/EC MN HAS
LED TO ONLY SPRINKLES AT BEST AS THE AREA OF -RA MOVED EASTWARD.
ANOTHER AREA OF -RA...MIXED WITH -SN WAS DEVELOPING ALONG A WEAK SFC
LOW NEAR KGFK. ALTHOUGH THE SFC LOW WILL WEAKEN...STRONG CAA EVIDENT
JUST NORTH OF THE CANADIAN BORDER WILL ENHANCE THE SFC CONVERGENCE
ALONG THIS WEAK LOW AS IT MOVES SE ACROSS MN TODAY. AS PREVIOUSLY
STATED...INITIAL AIR MASS IS VERY DRY BLW 5K...BUT MOISTENS
CONSIDERABLY DURING THE MORNING AHEAD OF THIS SFC LOW.
THEREFORE...WITH THE STRENGTHENING SFC CONVERGENCE ALONG THE LEADING
EDGE OF COLD AIR...-RA WILL LIKELY HOLD TOGETHER ACROSS CENTRAL/EC
MN AND WC WI TODAY. THIS WAS ALSO NOTED IN THE LATEST WRF MODELS
FORECAST REFLECTIVITY PATTERN. THE STRENGTH OF THE CAA BEHIND THIS
FEATURE IS QUITE IMPRESSIVE FOR LATE OCTOBER WHICH WILL LEAD TO
TEMPS LIKELY FALLING BEHIND IT DURING THE AFTN. AS WINDS INCREASE
AND TEMPS FALL INTO THE 20S AND 30S...WIND CHILL VALUES WILL LIKELY
FALL INTO THE TEENS.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 353 AM CDT THU OCT 30 2014

THE LONG TERM FORECAST ISSUED THIS MORNING CHANGED VERY LITTLE
FROM THE PREVIOUS /DAY SHIFT/ FORECAST. THERE IS OVERALL GOOD
MODEL AGREEMENT IN THE LONG WAVE PATTERN AND PRETTY GOOD RUN-TO-
RUN CONSISTENCY. A STOUT AREA OF HIGH PRESSURE WILL QUICKLY DROP
SOUTH INTO THE DAKOTAS AND EVENTUALLY ACROSS MN BY FRIDAY MORNING.
THIS WILL BRING AN IMPRESSIVE SURGE OF COLD AIR AND STRONG WINDS
WITH IT. MOMENTUM TRANSFER APPROXIMATIONS FROM THE NAM/GFS
FORECAST SOUNDINGS SUGGEST PEAK WIND GUSTS UP NEAR 30-35KTS IN
WESTERN MN AND 25-30KTS ACROSS THE REST OF THE FORECAST AREA LATE
THURSDAY NIGHT AND FRIDAY MORNING. THE AIR MASS THAT ARRIVES ON
FRIDAY WILL BE THE COLDEST OF THE SEASON THUS FAR WITH MOST OF THE
GUIDANCE FORECASTING 850MB TEMPS BETWEEN -7C AND -11C BY FRIDAY
MORNING ACROSS THE LOCAL AREA...WHICH WILL BE THE COLDEST AIR OF
THE FALL SEASON SO FAR. THE WEEKEND STILL LOOKS TO BRING WARMER
TEMPS THAN FRIDAY BUT WILL REMAIN COOL OVERALL. MN/WI WILL FIND
ITSELF UNDER RIDGING THIS WEEKEND IN BETWEEN A DEEP TROUGH OFF
THE NORTHEAST COAST AND AN APPROACHING TROUGH FROM THE ROCKIES. BY
06-12Z SUNDAY THERE ARE TWO WELL-DEFINED PV BOOTS TRANSVERSING THE
CONUS WITH MN/WI RIGHT IN THE MIDDLE. EVENTUALLY THE SYSTEM OFF TO
OUT WEST ON SUNDAY WILL MOVE ACROSS THE HIGH PLAINS AND INTO
NORTHWEST MN AND SOUTHWEST ONTARIO MONDAY MORNING. THAT PUTS THE
FORECAST AREA RIGHT IN THE DRY SLOT ON MONDAY. THAT IS WHY /EVEN
WITH AN APPROACHING LOW AND COLD FRONT/ WE REALLY CAN`T GO HIGHER
THAN 30% FOR PRECIP EARLY NEXT WEEK. IT LOOKS LIKE CONVECTION WILL
LIGHT UP A STATE OR TWO TO OUR SOUTH MONDAY-MONDAY NIGHT. WE WILL
SEE A QUICK COOL DOWN ON TUESDAY BEHIND THIS SYSTEM. THE GFS/ECMWF
BEGIN TO DIVERGE BY THE MIDDLE OF NEXT...WITH THE ECMWF
AGGRESSIVELY BRINGING BACK WARMER AIR FROM THE SOUTHWEST AND THE
GFS KEEPING MN/WI IN COLD NORTHWEST FLOW. THERE`S ABOUT A 20C
DEGREE DIFFERENCE IN 850MB TEMPS BETWEEN THE TWO NEXT THURSDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 530 AM CDT THU OCT 30 2014

MAIN AVIATION CONCERN IS TIMING OF COLD FRONT AND ASSOCIATED MVFR
CIGS DEVELOPING BEHIND THE FRONT.

BASED ON CURRENT TRENDS OF SATELLITE IMAGERY OF THE LOWER CIGS IN
NW MN AND WINDS...WC MN WILL SEE FRONTAL PASSAGE ARND 14-16Z.
ACROSS SW/CENTRAL MN ARND 16-18Z...AND THRU MOST OF EC/SC MN AND
WC WI BETWEEN 19-21Z. INITIALLY WINDS WILL SHIFT TO THE N/NNW ARND
10 KTS...WITH STRONGER WINDS GUSTING UP TO 20-30 KTS WITHIN AN HR
OR TWO. MVFR CIGS SEEM LIKELY ALONG AND BEHIND THIS FRONT FOR A
FEW HRS...BUT CONFIDENCE REMAINS LOW ON HOW LOW THE CLD CIGS
BECOME DURING THE AFTN HRS. MOST OF THE MVFR CIGS AFFECTING MPX
TAFS WILL BE AFT 18Z...SO THE NEXT SET OF TAFS WILL HAVE A BETTER
HANDLE ON TIMING AND CLD BASES. CIGS SHOULD LIFT TO VFR AND
SCATTER OUT DURING THE LATE AFTN AND EVENING HRS FROM NW TO SE.

KMSP...

FRONTAL PASSAGE WILL BE ARND 18-19Z...WITH SOME VCSH ALONG IT.
HOWEVER...VSBYS WILL NOT BE A PROBLEM ON ANY RAIN THAT DEVELOPS.
WORSE CONDS WILL OCCUR AFT 18Z SO TIMING ON MVFR CIGS WILL BE
UPDATED AS NEEDED. STRONG N/NNW WINDS WILL DEVELOP AN HR OR TWO
AFTER THE INITIAL FRONTAL PASSAGE WITH GUSTS UP TO 26 KTS LIKELY
DURING THE LATE AFTN/EARLY EVENING TIME FRAME. WINDS WILL SLOWLY
DECREASE OVERNIGHT WITH SKIES BECOMING CLEAR.

/OUTLOOK FOR KMSP/

FRI...VFR. WINDS N 10-15 KTS.
SAT...VFR. WINDS SE 10-15 KTS.
SUN...VFR. WINDS SSE 10-15 KTS.

&&

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

$$

SHORT TERM...JLT
LONG TERM...CLF
AVIATION...JLT




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