Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 290923
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
423 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 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1159 PM CDT TUE OCT 28 2014

MAIN CONCERN IS WHEN MVFR/IFR CIGS BECOME VFR WEDNESDAY...WITH
SHRA POSSIBLE LATE IN THE TAF PERIOD AT KAXN.

HIGH CONFIDENCE THAT MVFR CIGS WILL CONTINUE FOR
KAXN/KSTC/KRHN/KEAU THRU THE NEXT 6 HRS...WITH MOST AREAS HOLDING
BLW 3K UNTIL AFT 18Z. CONFIDENCE IS LOW ON WHEN THE MVFR CIGS LIFT
TO VFR ACROSS EASTERN MN/WESTERN MN WEDNESDAY AFTN. WHEN THE CYCLONIC
FLOW BECOMES ANTI-CYCLONIC IN MN WILL BE KEY ON WHEN THE CLDS
BEGIN TO BREAK UP AND LIFT TO VFR. BASED ON THE LATEST MODEL
INFORMATION...THE SFC RIDGE WILL NOT MOVE ACROSS THE AREA UNTIL
AFT 18Z...WITH THE EXCEPTION OF KAXN. THEREFORE...MVFR CIGS WILL
LIKELY CONTINUE. THE NEXT SYSTEM WILL RAPIDLY MOVE TO THE SE WED
NIGHT AND POSSIBLY HAVE -SHRA AT KAXN BY THE END OF THE TAF
PERIOD. INTRODUCE VCSH FOR NOW. WNW/NW WINDS WILL DECREASE
OVERNIGHT AND BECOME WEST/WSW BY THE AFTN...THEN MORE SW/S DURING
THE EVENING.

KMSP...

HIGH CONFIDENCE WITH MVFR CIGS /2K TO 2.5K/ CONTINUING THRU THE
NEXT 6 HRS...WITH LOW CONFIDENCE ON WHEN THE MVFR CIGS RISE TO VFR
OR SCATTER OUT BY THE AFTN. WILL CONTINUE THE SAME TREND WITH MVFR
CIGS UNTIL 18-21Z OR HIGH BASED MVFR CIGS. THERE COULD BE A PERIOD
OF VFR OR SCT030 AFT 18Z IF BOUNDARY LAYER MOISTURE MIXING OUT
FASTER. SFC WINDS WILL CONTINUE GUSTY UNTIL 9Z...WITH A SLOW TREND
OF WNW WINDS DECREASING TO 7=9 KTS BY THE MID/LATE MORNING. AFT 18Z
WINDS WILL BE W/WSW UNDER 6 KTS...BECOMING MORE SW/S LATE IN THE
EVENING.

/OUTLOOK FOR KMSP/

THU...VFR. WINDS VARIABLE 5 KTS BECOMING NW.
FRI...VFR. WINDS N 5-10 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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