Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 310543
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1143 PM CST FRI JAN 30 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 306 PM CST FRI JAN 30 2015

THE SHORT TERM FORECAST IS QUIET WITH SEASONAL TEMPERATURES AND
LITTLE CHANCE FOR PRECIPITATION. HIGH PRESSURE IS CURRENTLY
SLIDING SOUTHEAST OF THE FORECAST AREA AND A WEAK SURFACE TROUGH
IS SLOWLY MOVING EAST ACROSS THE DAKOTAS. THE AIR MASS JUST AHEAD
OF THIS TROUGH IS QUITE WARM WHERE TEMPS CLIMBED TO NEAR 50 TO OUR
WEST THIS AFTERNOON. THIS TROUGH WILL MOVE THROUGH TONIGHT...BUT
THE FRONT IS REALLY MORE OF AN OCCLUDED FRONT WITH THE COLDER AIR
COMING IN FAIRLY QUICKLY BEHIND THE FRONT. IN TERMS OF CLOUD
COVER...CLEARING TONIGHT SHOULD BE REPLACED BY A STRATUS DECK
COMING IN FROM THE NORTH WITH THE COLD AIR. 850MB TEMPS ARE
EXPECTED TO -10C TO -12C BY 00-06Z.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 306 PM CST FRI JAN 30 2015

FOCUS THIS SHIFT IS AT THE BEGINNING OF THE LONG TERM
PERIOD...BEGINNING SATURDAY NIGHT. A COMPLICATED FORECAST
SITUATION IS EVOLVING AS A NORTHERN STREAM WAVE OVER BRITISH
COLUMBIA IS FORECAST TO PHASE WITH A SOUTHERN STREAM SYSTEM COMING
OUT OF THE SOUTHWESTERN CONUS. THE DETAILS WILL BE GREATLY
AFFECTED BY HOW THE SOUTHERN AND NORTHERN STREAM SYSTEMS
MERGE...AND WHEN. THE MODELS IN THE PAST HAVE STRUGGLED IN
PROPERLY HANDLING THIS TYPE OF INTERACTION AT TIMES...AND MOST OF
THE MOISTURE WILL COME WITH THE SOUTHERN STREAM SYSTEM.

THE CONSENSUS WAS A SHIFT NORTHWARD TODAY...SO INCREASED POPS FOR
THE SOUTHERN HALF OF THE AREA...WITH HIGH PROBABILITIES OF
ACCUMULATING SNOW ALONG THE IOWA BORDER. THE HEAVIEST AMOUNTS WILL
FALL SOUTH OF OUR AREA...BUT AT THIS TIME IT LOOKS AS IF WE`LL GET
CLIPPED WITH A FEW INCHES OF LIGHT SNOW ALONG THE IOWA BORDER.
WHERE I LACK CONFIDENCE IS IN THE MERGING OF THE NORTHERN AND
SOUTHERN STREAM WAVES BECAUSE THE NORTHERN WAVE WILL NEED TO
ACCELERATE AND MERGE WITH THE SOUTHERN WAVE BEFORE ITS EAST OF
IOWA. IF THIS OCCURS...THE NORTHERN WAVE IS STILL LIKELY TO BRING
LIGHT SNOW TO SOUTHERN AND SOUTHWESTERN MN...BUT WITH LIGHTER
AMOUNTS. IF THE MERGE CAN HAPPEN BEFORE THE SOUTHERN SYSTEM MOVES
TOO FAR EAST...AMOUNTS ALONG THE SOUTHERN THIRD OF THE STATE COULD
BE HIGHER DUE TO BETTER FORCING AND MORE ABUNDANT MOISTURE. PLENTY
OF TIME TO HASH OUT THE DETAILS OF THIS SYSTEM BUT FOR NOW
GENERALLY WENT FOR 1-3" ACROSS THE FAR SOUTH. THIS FORECAST LEANED
MOSTLY TOWARD THE ECMWF SOLUTION...BUT THE 18Z NAM ALSO CAME IN
AND BACKED OFF ON AMOUNTS IN OUR AREA FROM THE 12Z RUN.

LOOKING AHEAD...TEMPERATURES WILL COOL BEHIND THESE SYSTEMS WITH
SHORTWAVES MOVING THROUGH THE GENERAL UPPER MIDWEST REGION EVERY
FEW DAYS THROUGH THE END OF THE PERIOD. OPPORTUNITIES TO PICK UP
LIGHT SNOW REMAIN IN THE FORECAST FOR THOSE SYSTEMS.
OTHERWISE...NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES FOR MUCH OF
NEXT WEEK. THERE ARE INDICATIONS THOUGH THAT THE WESTERN CONUS
RIDGE WILL ADVANCE EAST AROUND NEXT WEEKEND AND PUSH US BACK TO
ABOVE NORMAL TEMPERATURES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1129 PM CST FRI JAN 30 2015

CURRENT MVFR CIGS ON TRACK TO SPREAD S/SE ACROSS MPX CWA BY
12Z. THERE MAY BE A DELAY OF AN HR OR TWO IN THE SOUTHERN PART OF
MPX CWA...BUT STILL HAVE HIGH CONFIDENCE OF THE CONTINUED TREND.
UPSTREAM ACROSS SOUTH CENTRAL CANADA...STRONG EVIDENTS OF DRIER
AIR MOVING SOUTHWARD WHICH MEANS THE MVFR CIGS WILL LIKELY BEGIN
TO BREAK UP OR DISSIPATE BY MID/LATE MORNING ACROSS CENTRAL
MN. HOW FAR SOUTH THE DRIER AIR WILL SPREAD IS THE MAIN
CONCERN...ESPECIALLY FOR KRWF/KEAU WHERE MVFR MAY CONTINUE THRU
THE TAF PERIOD. THE WORSE CONDS WILL OCCUR AFT 06Z/01...BUT ENOUGH
CONFIDENCE TO INTRODUCE -SN AT KRWF BY 3Z. WINDS WILL SHIFT TO THE
N/NE TODAY WITH GUSTY WINDS DEVELOPING SATURDAY AFTN/EVENING FROM
THE NE.

KMSP...

HIGH CONFIDENCE OF VFR CONDS THRU 12Z...WITH CIGS LOWERING TO MVFR
BY 12-14Z. TIMING IS THE MAIN ISSUE BUT CURRENT TRENDS SEEM
REASONABLE OF VFR THRU 12Z. MVFR CIGS MAY CONTINUE THRU THE AFTN
BEFORE DRIER AIR FILTERS IN FROM THE N/NE. CONFIDENCE REMAINS LOW
ON WHEN THE MVFR CIGS DISSIPATE OR CONTINUE BASED ON THE STRENGTH
OF THE DRIER AIR. HAVE INTRODUCED -SN AFT 9Z AS A STORM SYSTEM
ACROSS THE PLAINS BRUSHES THE SOUTHERN PART OF MPX CWA. WINDS WILL
SHIFT TO THE NORTH BY 10-12Z...THEN MORE NE AND INCREASING DURING
THE AFTN/EVENING WITH GUSTY WINDS.

/OUTLOOK FOR KMSP/

SUN...MVFR CIGS/VSBYS EARLY WITH -SN. NORTH WIND 10 TO 15 KT.
SUN NIGHT...VFR. NORTH WIND BECOMING SW 5-10 KT.
MON...VFR. SOUTHWEST WIND 5 TO 10 KT.
MON NIGHT...MVFR CEILINGS POSSIBLE. SOUTHWEST WIND 5 TO 10 KT.
TUE...MVFR CIGS/VSBYS IN -SN POSSIBLY IFR AT TIMES. WIND BECOMING
NORTH AROUND 10 KT.

&&

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

$$

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


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