Area Forecast Discussion
Issued by NWS Twin Cities, MN

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557
FXUS63 KMPX 080356
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
956 PM CST SUN FEB 7 2016

.UPDATE...
ISSUED AT 955 PM CST SUN FEB 7 2016

UPDATED TO INCLUDE 06Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 225 PM CST SUN FEB 7 2016

SEVERAL CONCERNS OVER THE NEXT 24 HRS AS A BLIZZARD & WINTER
STORM WARNING TAKES EFFECT IN THE NEXT FEW HRS.

FIRST...

UPDATED EARLIER ON THE DELAY OF THE BLIZZARD WARNING IN PARTS OF SW
MN DUE TO VERY MILD TEMPS DURING THE DAY AND SNOWFALL HADN/T
MATERIALIZE. PLUS WIND SPEEDS HAVE NOT YET BECOME STRONG ENOUGH TO
CREATE THE BLOWING SNOW WHERE A CRUST ON THE SNOWPACK HAD OCCURRED.
OTHER AREAS THAT HAVE A WINTER STORM WARNING AND/OR ADVISORIES IN
EFFECT TONIGHT REMAIN FINE DUE TO SIGNIFICANT BLOWING SNOW STILL
EXPECTED...BUT LIKELY NOT UNTIL LATER THIS EVENING.

CURRENT REGIONAL RADAR AND WATER VAPOR IMAGERY INDICATED A POTENT
SHORT WAVE MOVING SOUTHWARD ACROSS NORTHERN MN THIS AFTN. THIS SHORT
WAVE WILL BE THE MAIN FACTOR OF GENERATING SNOWFALL THIS EVENING.
PLUS...THE DENDRITIC ZONE DEEPENS QUITE RAPIDLY BEHIND THE ARCTIC
FRONT THAT WAS CO-LOCATED WITH THE SHORT WAVE. ALTHOUGH THE WIND
SPEEDS HAVE NOT DEVELOPED AS STRONG AS PREVIOUSLY INDICATED AS OF 2
PM...THESE WINDS WILL LIKELY DEVELOP THIS EVENING ONCE THIS SHORT
WAVE MOVES THROUGH. AGAIN...IT IS MORE OF A DELAY OF THE BLIZZARD
CONDITIONS IN SW/SC MN TONIGHT. AS PREVIOUSLY STATED...THE DENDRITIC
GROWTH ZONE DEEPENS ENOUGH THAT WITH ANY MOISTURE RIDING SOUTHWARD ON
THE UPPER LEVEL STORM SYSTEM...PERIODS OF LIGHT SNOW WILL OCCUR.
ALTHOUGH QPF AMTS WILL BE LIGHT AND UNDER A TENTH OF AN INCH. A GOOD
AREA OF 1-2 INCHES OF SNOW IS LIKELY BY MONDAY MORNING FOR MOST OF
CENTRAL AND EASTERN MN/WESTERN WI...WITH AMOUNTS LESS THAN 1 INCH IN
SW/WC/SC MN.

AS PER WIND SPEEDS... AREA MODEL SOUNDINGS DEVELOP A DRY ADIABATIC
LAPSE RATE BETWEEN THE SFC...UP TO 90/85H. WITH THIS TYPE OF
SOUNDING...MOMENTUM TRANSFER WILL BE MAXIMIZED FROM WINDS ON TOP OF
THE THIS STEEP LAPSE RATE. THEREFORE...AS THE SHORT WAVE MOVES
THRU AND STRONGER WINDS ALOFT BEGIN TO MIX DOWN...MUCH STRONGER WINDS
WILL DEVELOP...LEADING TO BLIZZARD CONDS.

EXPECT THE STRONG WINDS TO CONTINUE THRU NOON ON MONDAY. THE PRESSURE
GRADIENT SHOULD BEGIN TO LESSEN BY MONDAY AFTN...DECREASING THE WIND
SPEEDS. ALTHOUGH BLOWING SNOW WILL CONTINUE AS WIND GUSTS OF 30 TO 40
MPH WILL LIKELY HOLD THROUGH THE AFTN.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 225 PM CST SUN FEB 7 2016

THE LONGER TERM CONCERN IS TIMING OF ANY SNOW MOVING ALONG THE
BAROCLINIC ZONE OFF TO THE WEST OF THE AREA...AS THE UPPER AIR
PATTERN BECOMES AMPLIFIED WITH THE EASTERN CONUS TROUGH AND RIDGE
TO THE WEST.

ANY SNOW SHOWERS/FLURRIES AND PATCHY BLOMING SNOW WILL COME TO AN
END MONDAY NIGHT OVER THE CWA. SOME CLEARING IS LIKELY IN THE WAKE
OF THE SYSTEM. WHERE IT DOES CLEAR...TEMPERATURES SHOULD BE ABLE
TO COOL THROUGH THE SINGLE DIGITS TO AROUND ZERO IN CENTRAL MN.

THE SURFACE RIDGE BUILDS ACROSS THE AREA TUESDAY AND LINGERS OVER
THE AREA THROUGH THE WORK WEEK. H85 TEMEPRATURES REMAIN GENERALLY
MINUS 15 TO MINUS 20 OVER THE EASTERN HALF OF THE CWA. THIS SHOULD
PROVIDE THE COOLER THAN NORMAL TEMPERATURES THE CFS HAS BEEN
SHWOOING THE LAST SEVERAL RUNS. THE DETERMINISTIC RUNS CONTINUE TO
HAVE SOME RUN TO RUN DISCONTINUITY PROBLEMS WITH ANY POSSIBLE
LIGHT SNOW BAND THAT IS GENERATED WITH ANY WEAK IMPULSE THAT WORKS
OVER THE WESTERN RIDGE. HAVE OPTED TO CONTINUE THE DRY FORECAST
FOR THE WEEK AS THE SURFACE RIDGE DOMINATES. AS THE EASTERN TROUGH
TRANSLATES FARTHER EAST INTO THE WEEKEND...WE SHOULD SEE A SLOW
WARMING TRNED ALONG WITH A CHANCE OF SNOW RETURNING TO THE AREA
ABOUT SUNDAY OR SO.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 955 PM CST SUN FEB 7 2016

FORECAST THINKING HASN/T CHANGED MUCH FROM EARLIER ISSUANCE. MVFR
CEILINGS LOOK TO PREDOMINATE THROUGH THE PERIOD... ALTHOUGH THERE
REMAINS SOME QUESTION AS TO WHETHER THEY WILL SCATTER OUT LATER IN
THE DAY OR DURING THE EVENING. CONTINUED TO GO WITH A PESSIMISTIC
FORECAST IN THAT RESPECT... WITH THE GFS AND NAM FORECAST
SOUNDINGS SHOWING PLENTY OF LOW LEVEL MOISTURE REMAINING TRAPPED
BENEATH THE INVERSION INTO MONDAY EVENING WITH CYCLONIC FLOW STILL
OVER THE REGION. VISIBILITIES REMAIN A TOUGH CALL... BUT LOOKS
LIKE THEY WILL MAINLY REMAIN AOA 2SM IN FALLING SNOW... WITH
OCCASIONAL BLOWING OR BURSTS OF HEAVIER SNOW PERHAPS TAKING THEM
BLO 1SM AT TIMES.

KMSP...CEILINGS LOOK TO BE TEMPERMENTAL FOR THE INITIAL 3 HOURS OR
SO... ALTHOUGH THEY SHOULD GENERALLY BE MVFR. VISIBILITIES COULD
OCCASIONALLY DIP BELOW 2SM... BUT UNLESS BLOWING SNOW BECOMES MORE
OF AN ISSUE IT APPEARS THEY WON/T DO SO FREQUENTLY. KEPT CEILING
IN PLACE THROUGH THE PERIOD... BUT AS MENTIONED ABOVE... IT IS
POSSIBLE THEY COULD SCATTER OUT SOONER AS LAMP AND MOS GUIDANCE
SUGGEST. BUT... IN THESE SITUATIONS THEY OFTEN STICK AROUND LONGER
THAN PROGGED... AND FORECAST SOUNDINGS CERTAINLY SUGGEST THAT WILL
BE THE CASE THIS TIME.

/OUTLOOK FOR KMSP/
MONDAY OVERNIGHT AND TUESDAY...MVFR CEILINGS POSSIBLE. NORTHWEST
WIND 15 TO 25 KT.
TUESDAY NIGHT...VFR. NORTHWEST WIND 15 TO 20 KT.
WEDNESDAY...VFR. NORTHWEST WIND 10 TO 20 KT DECREASING TO LESS
THAN 10 KT.
WEDNESDAY NIGHT AND THURSDAY...MVFR CEILINGS AND VISIBILITIES
POSSIBLE WITH A CHANCE OF SNOW. VARIABLE WIND LESS THAN 10 KT
BECOMING NORTH AROUND 10 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...BLIZZARD WARNING UNTIL NOON CST MONDAY FOR MNZ065>067-073>076-
     082>085-091>093.

     WINTER STORM WARNING UNTIL NOON CST MONDAY FOR MNZ041-047-048-
     054>058-064.

     WINTER WEATHER ADVISORY UNTIL NOON CST MONDAY FOR MNZ042>045-
     049>053-059>063-068>070-077-078.

&&

$$

UPDATE...
SHORT TERM...JLT
LONG TERM...DWE
AVIATION...



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