Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 291031
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
531 AM CDT WED OCT 29 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 241 AM CDT WED OCT 29 2014

MAIN CONCERN IS TEMPS TODAY AS ASSOCIATED CLOUD COVER/LATE OCTOBER
SUN ANGLE MAY HOLD BACK TEMPS FROM RISING TOO MUCH UNTIL MID/LATE
AFTN. CAA WILL REMAIN FOR MOST OF THE MORNING...SO TEMPS MAY
ACTUALLY HOLD OR FALL A DEGREE OR TWO BEFORE STARTING TO RISE BY
LATE MORNING. LOW TO MID 40S SEEM REASONABLE BASED ON THE
ANTICIPATED CLOUDS HOLDING ON...AND TEMPS STILL IN THE 30S.

A FAST MOVING SHRTWV THAT WAS NOTED ACROSS NORTHERN WASHINGTON STATE
EARLY THIS MORNING WILL BE THE MAIN FORECAST CONCERN LATER THIS
EVENING/OVERNIGHT WITH A CHC OF RAIN/SNOW. INITIALLY...DRY AIR MASS
WILL CONTROL THE WEATHER DURING THE LATE AFTN/EVENING TIME FRAME.
THIS INITIAL DRY AIR MASS MAY ACTUALLY HELP WITH A MIXTURE OF
SNOW/RAIN BEFORE CHANGING OVER TO ALL RAIN DURING THE OVERNIGHT HRS.
MAX WET BULB TEMPS /1 KM LAYER/ DURING THE EVENING ACROSS
EASTERN MN/WESTERN WI ARE COOL ENOUGH THAT IF PRECIPITATION DEVELOPS
EARLIER...THE MAIN TYPE COULD BE SNOW. HOWEVER...THIS WILL QUICKLY
CHANGE BACK TO RAIN AS THE THERMAL PROFILE WARMS AS THE SHRTWV
QUICKLY MOVES EASTWARD ACROSS THE DAKOTAS. WRF MODELS SIMULATED
PRECIPITATION TYPE DOES HAVE A SIMILAR SCENARIO WITH SOME MIXTURE OF
RAIN/SNOW ACROSS CENTRAL/EC MN/WC WI DURING THE ONSET OF
PRECIPITATION.

ALTHOUGH PRECIPITATION IS VERY LIKELY ACROSS MPX CWA LATE
TONIGHT...INITIAL DRY MASS MAY PRECLUDE ANY SIGNIFICANT AMTS. A
GENERAL FEW HUNDREDTHS OF AN INCH OF LIQUID WATER IS POSSIBLE WITH
MOSTLY TRACE AMTS ACROSS MPX CWA. WILL CONTINUE 20/30/40% POPS AS
MEASURABLE PRECIPITATION WILL BE LOW.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 241 AM CDT WED OCT 29 2014

A HIGHLY AMPLIFIED AND HIGHLY PROGRESSIVE PATTERN TAKES SHAPE IN
THE EXTENDED. THIS WILL LEAD TO A COUPLE PROTOTYPICAL FALL
TEMPERATURE SWINGS AND AT LEAST A COUPLE BLUSTERY DAYS.
OVERALL...STILL A DRY PATTERN WITH LITTLE CHANCE FOR PRECIP UNTIL
EARLY NEXT WEEK AND EVEN THAT DOESN`T LOOK OVERLY IMPRESSIVE FOR
RAIN.

THE PRECIP EVENT MENTIONED IN THE SHORT TERM DISCUSSION WILL
QUICKLY MOVE OUT OF THE FORECAST AREA THURSDAY MORNING. THERE IS
REALLY GOOD MODEL AGREEMENT AMONGST THE NAM/GFS/ECMWF IN THE RAPID
BUILDING OF HIGH PRESSURE ACROSS THE CANADIAN PRAIRIES DURING THE
DAY ON THURSDAY. THIS HIGH WILL QUICKLY DROP SOUTH INTO THE
DAKOTAS THURSDAY NIGHT AND 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. THE LAST COLD
OUTBREAK OCCURRED DURING THE FIRST WEEK OF OCTOBER WHEN MANY
LOCATIONS SAW 40S FOR HIGHS...THAT WAS WITH 850MB TEMPS OF ABOUT
-4C. IN ADDITION TO THE COLDER AIR MASS...WE ARE NOW APPROACHING
NOVEMBER AND HAVE LOST BETWEEN 60-90 MINUTES OF DAYLIGHT SINCE
THAT EARLY OCTOBER COLD SNAP...NOT TO MENTION WE ALSO HAVE A LOWER
SUN ANGLE. A LOT OF THE FORECAST AREA MIGHT NOT MAKE IT OUT OF THE
30S FOR HIGHS ON FRIDAY...WHICH WOULD MAKE IT THE COLDEST
HALLOWEEN SINCE 2006 WHEN THERE WAS A HIGH OF 36 IN THE TWIN
CITIES...A HIGH OF 33 IN ST. CLOUD...AND 38 IN EAU CLAIRE. A
BLUSTERY NORTH FLOW WILL DROP WIND CHILLS INTO THE 20S DURING
FRIDAY EVENING.

THE WEEKEND WILL BRING WARMER TEMPS THAN FRIDAY BUT STILL REMAIN
COOL OVERALL. THE COLDEST AIR WILL SLIDE EAST BY FRIDAY NIGHT.
MN/WI WILL FIND ITSELF UNDER TRANSIENT RIDGING THIS WEEKEND IN
BETWEEN A DEEP TROUGH OFF THE NORTHEAST COAST AND AN APPROACHING
TROUGH FROM THE ROCKIES. THIS TROUGH BREAKS OFF A CUT-OFF LOW OVER
THE BAJA PENINSULA AND SWINGS THROUGH THE FORECAST AREA EARLY NEXT
WEEK. THE MODEL TIMING AND LOCATION ON THIS TROUGH IS IN GOOD
AGREEMENT FOR A 150-HR FORECAST. THIS TROUGH IS THE REASON FOR
THE CHANCE POPS IN THE FORECAST EARLY NEXT WEEK - DOESN`T APPEAR
TO BE A MAJOR PRECIP EVENT AT THIS POINT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 519 AM CDT WED OCT 29 2014

CONTINUED HIGH CONFIDENCE ON MVFR CIGS FOR MOST OF MPX TAFS UNTIL
18Z WITH A SLOW TREND OF VFR DURING THE AFTN FROM WEST TO EAST.
KEAU MAY NOT GET ABV 3K UNTIL AFT 23Z BASED ON THE SFC RIDGE
HOLDING BACK ACROSS MN. WINDS WILL SLOWLY DECREASE THIS MORNING
WITH A FEW GUSTS UP TO 20 KTS UNTIL 15Z. WINDS WILL BACK TO THE
W/SW DURING THE AFTN...WITH A MORE S/SSE FLOW OVERNIGHT. -SHRA
WILL BE POSSIBLE LATE EVENING ACROSS WESTERN MN...THEN MOVE
EASTWARD TOWARD EASTERN MN BY 9-12Z. CIGS ARE EXPECTED TO REMAIN
VFR WITH ANY PRECIPITATION THAT OCCURS TONIGHT.

KMSP...

HIGH CONFIDENCE OF MVFR CIGS THRU 18Z. CIGS SHOULD SLOWLY LIFT AND
DISSIPATE DURING THE AFTN WITH VFR CONDS DURING THE
EVENING/OVERNIGHT PERIOD. WINDS WILL BE GUSTY EARLY AT 20
KTS...THEN BACK TO THE WEST/SW THIS AFTN UNDER 10 KTS...BECOMING
MORE S/SSE OVERNIGHT. -SHRA WILL BE POSSIBLE AFT 9Z...BUT
CONFIDENCE REMAINS LOW ON COVERAGE AND CIGS. CHC OF MVFR CIGS
THURSDAY MORNING.

/OUTLOOK FOR KMSP/

THU AFTN...VFR. WINDS BECOMING N/NNW AND INCREASING TO 15-25 KTS.
FRI...VFR. WINDS NNE 10-15 KTS EARLY...DECREASING TO 5 KTS.
SAT...VFR. WINDS SE 10-15 KTS.

&&

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

$$

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




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