660
FXUS63 KMPX 190011
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
611 PM CST FRI JAN 18 2019
UPDATE
FOR 00Z AVIATION DISCUSSION BELOW
SHORT TERM
(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 354 PM CST FRI JAN 18 2019
IMPRESSIVE SNOW STORM ONGOING ACROSS SOUTHERN MN THIS AFTERNOON.
WE'VE SEEN A VERY INTENSE 40-50 MILE WIDE BAND OF SNOW DEVELOP,
DRIVEN BY VERY STRONG FGEN IN THE H7-H6 LAYER THAT IS BEING AIDED BY
THE PRESENCE OF ARCTIC AIR OVER NORTHERN MN, WHERE TEMPERATURES
HAVE STRUGGLED TO REACH -10F. REFLECTIVITY VALUES IN THE BAND ARE
MAXING OUT IN THE 30-35 DBZ RANGE, WHICH IS ABOUT AS HIGH OF A
REFLECTIVITY YOU CAN EXPECT WHEN DEALING WITH DRY SNOW. WE HAVE
UPDATED THE FORECAST WITHIN THIS BAND TO HAVE 8-10" FROM ST. JAMES
OVER TOWARD ALBERT LEA, WITH LOCALIZED AMOUNTS NEAR A FOOT ON THE
HIGH END NOT OUT OF THE QUESTION. HI-RES MODELS THIS MORNING DID A
GOOD JOB AT PICKING UP ON THE SLIGHT NORTHWARD SHIFT OF THE HEAVIEST
BAND, BUT WHAT'S INTERESTING IS THERE HAS BEEN VIRTUALLY NO SHIFT IN
HOW FAR NORTH THE FLAKES FLY, WITH AN INCH OF SNOW GETTING ABOUT AS
FAR NORTH AS CHANHASSEN OVER TO LAKEVILLE IN THE TWIN CITIES METRO.
GIVEN THE CHANGES WE'VE SEEN WITH THE HI-RES MODELS, WE TACKED ON A
ROW OF COUNTIES TO THE NORTH SIDE OF THE EXISTING
WARNINGS/ADVISORIES AND ALSO DELAYED THEIR END AN EXTRA 3 HOURS AS
WE HAVE ALSO SLOWED SOME THE DEPARTURE OF THE SNOW.
ATTENTION THEN TURNS TO TONIGHT WITH THE MAIN QUESTION BEING HOW
COLD DOES IT GET AND WHAT DOES THAT MEAN FOR WIND CHILL HEADLINES.
GIVEN HOW COLD THE AIR IS JUST TO OUR NORTH, WE DID NUDGE LOWS DOWN
A FEW DEGREES AND WE COULD END UP GETTING COLDER THAN CURRENTLY
FORECAST IF SKIES CLEAR OUT FASTER THAN CURRENTLY PROJECTED. WINDS
WON'T BE SCREAMING THROUGH THE NIGHT, BUT THE PERSISTENT 4-8MPH
NORTH WIND WILL BE ENOUGH TO GENERATE WIND CHILLS BETWEEN 25 AND 35
BELOW ZERO IN WESTERN AND CENTRAL MN WHERE WE HAVE POSTED A WIND
CHILL ADVISORY.
SATURDAY WILL BE A MAINLY SUNNY, THOUGH COLD DAY WITH THE ARCTIC
AIRMASS OVERHEAD. LOWERED HIGHS A DEGREE OR TWO WITH BLENDED
GUIDANCE COMING IN COLDER AS WELL WITH HIGHS STRUGGLING TO HIT 0 IN
WESTERN MN AND 10 IN WESTERN WI.
LONG TERM
(SUNDAY THROUGH FRIDAY)
ISSUED AT 354 PM CST FRI JAN 18 2019
OVERALL, LITTLE CHANGES WERE MADE TO THE LONG TERM PERIOD. A COLDER
THAN NORMAL PERIOD IS STILL ON TRACK THROUGH NEXT WEEK, WITH A
COUPLE OPPORTUNITIES OF LIGHT SNOW.
THE FIRST LIGHT SNOW EVENT COMES SATURDAY NIGHT AND THE FORECAST FOR
THIS ONE HAS NOT CHANGED. A VORTICITY MAX WILL MOVE THROUGH THE AREA
WITH LOW LEVEL SUPPORT FROM DECENT 850MB THETA-E ADVECTION MOVING
THROUGH THE AREA. GENERALLY, AN INCH OR SO OF SNOW IS POSSIBLE WITH
THIS ACROSS WESTERN AND SOUTH CENTRAL MN.
THE NEXT SYSTEM WILL TAKE SHAPE ACROSS COLORADO MONDAY, SENDING A
WARM ADVECTION BAND OF SNOW THROUGH MUCH OF CENTRAL AND NORTHERN MN.
WHILE MUCH OF THE LOCAL AREA LOOKS TO MISS THIS INITIAL BAND RIGHT
NOW, THE UPPER TROUGH ITSELF WILL PUSH THROUGH MONDAY NIGHT INTO
TUESDAY WHILE THE SURFACE LOW MOVES NORTHEAST THROUGH EASTERN IOWA.
THIS IS A FAVORABLE TRACK FOR DECENT SNOW FOR OUR LOCAL AREA,
HOWEVER THE LOW WILL ACTUALLY BE DECAYING AS IT MOVES THROUGH THE
MIDWEST AND WILL MOVE THROUGH RATHER QUICKLY. STILL, BROAD MODEST
FORCING STILL INDICATES THAT A WIDESPREAD LIGHT SNOW EVENT IS
LIKELY. BLOWING SNOW REMAINS A CONCERN FOR TUESDAY ACROSS WESTERN
MN WITH STRONG NORTHWEST WINDS DEVELOPING.
NORTHWEST FLOW STILL LOOKS TO ROUND OUT THE WEEK, WITH SOME
DISAGREEMENTS ON THE EXACT TRACK OF A LATE WEEK CLIPPER COMING DOWN
FROM CANADA. THERE IS POTENTIAL FOR ADDITIONAL LIGHT SNOW DEPENDING
ON THE TRACK. OVERALL, AN ACTIVE AND COOL PATTERN THROUGH NEXT
WEEK.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 612 PM CST FRI JAN 18 2019
SNOW AT SOUTHERN SITES WILL CONTINUE TO TAPER OFF THIS EVENING,
WITH CONDITIONS RETURNING TO VFR AREA-WIDE AND CLEARING SKIES
OVERNIGHT. NORTHERLY WINDS BELOW 10 KNOTS WILL PREVAIL FOR MUCH
OF THE PERIOD UNTIL THEY BACK TO THE NORTHWEST ON SATURDAY AFTERNOON.
KMSP...
A LOW-END VFR CEILING TO START THE PERIOD WILL SCATTER OUT BETWEEN
06Z AND 09Z WITH MOSTLY CLEAR SKIES FOR SATURDAY.
/OUTLOOK FOR KMSP/
SUN...VFR. CHC MVFR LATE. WIND SE 5-10 KTS.
MON...MVFR WITH -SN LIKELY LATE. WIND SE 10-15 KTS.
TUE...IFR, BCMG MVFR IN AFTN. -SN LIKELY IN MRNG. WIND NW AT 15G25
KTS.
MPX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CST SATURDAY FOR MNZ066>070-
076>078.
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM CST SATURDAY
FOR MNZ041>045-047>051-054>058-064-065-073.
WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR
MNZ055>057-065.
WINTER STORM WARNING UNTIL 1 AM CST SATURDAY FOR MNZ054-064-
073>075-082>085-091>093.
SHORT TERM...MPG
LONG TERM...SPD
AVIATION...LS
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