Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 221902
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
202 PM CDT WED OCT 22 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT WED OCT 22 2014

EARLY MORNING WATER VAPOR IMAGERY REVEALS A NICE CIRCULATION
CURRENTLY MOVING NORTHEAST INTO SOUTHERN SASKATCHEWAN FROM
NORTHERN MONTANA. COUPLING THIS IMAGE WITH RAP ANALYZED 500H
INDICATES THE PRESENCE OF A NEGATIVELY TILTED SHORTWAVE TROUGH.
THIS FEATURE HAS PRODUCED SHOWERS AND THUNDERSTORMS OVERNIGHT
ACROSS COLORADO...WESTERN NEBRASKA...WYOMING...MONTANA...AND
EXTREME WESTERN NORTH DAKOTA. THE TROUGH WILL CONTINUE IN A
GENERAL ENE DIRECTION THROUGH THE PERIOD AND WILL BRING RAINFALL
TO MOST OF THE CWA.

THIS MORNING...HI-RES GUIDANCE HAD BEEN INDICATING AN AREA OF
THUNDERSTORMS DEVELOPING IN THE ELEVATED INSTABILITY THIS MORNING
AHEAD OF THE MAIN TROUGH. THE HOPWRF STILL INDICATES THIS
POTENTIAL...AS DO THE NMM AND ARW. THE HRRR HOWEVER...DROPPED THIS
IDEA FROM ITS EARLIER RUNS AND MAY BE ON TO SOMETHING GIVEN THE
LATEST RADAR TRENDS ACROSS THE DAKOTAS. STILL...KEPT A LOW POP
MENTION FROM WESTERN MN AND NORTH AND WEST OF ST. CLOUD THROUGH
THE MORNING.

THE MAIN PRECIPITATION BAND WILL COME TOGETHER OVER THE NEXT FEW
HOURS ACROSS THE CENTRAL DAKOTAS AS A CONTINUATION OF THE ACTIVITY
SEEN OVERNIGHT IN THE AFOREMENTIONED AREAS OF CO/WY/NE. AS WE
HEAD INTO THE AFTERNOON...UPPER LEVEL DIVERGENCE THANKS TO AN
ENHANCED FLOW AT JET LEVEL TO THE NORTHWEST WILL BE SUPERIMPOSED
WITH THE VORT MAX AND FRONTOGENETIC FORCING IN THE LOW LEVELS
ACROSS THE EASTERN DAKOTAS. SATURATION WILL NOT BE A PROBLEM...BUT
THERE IS THE POTENTIAL THAT THUNDERSTORMS TO THE SOUTH SIDE OF THE
EXPANDING PRECIP BAND COULD LIMIT QPF TO THE NORTH.

HI-RES MODELS AGREE THAT THE NORTH TO SOUTH ORIENTED PRECIP BAND
WILL BE PROGRESSING EAST ACROSS WESTERN MN THIS EVENING. SIMULATED
REFLECTIVITY FROM THESE MODELS SUGGEST LIMITED RETURNS NORTH OF
ABOUT MANKATO. THIS LINES UP WELL WITH THE NORTHERN EXTENT OF THE
NEGATIVE BEST LI`S WHICH WILL BE CONFINED TO AREAS SOUTH OF ABOUT
MANKATO TONIGHT. HENCE...ISOLATED THUNDER REMAINS IN THE FORECAST
FOR THIS AREA...WHILE MORE STRATIFORM SHOWERS ARE EXPECTED TO THE
NORTH. IN GENERAL...A RANGE OF 0.15-0.35" IS NOW IN THE FORECAST
WITH THE MAXIMA BEING IN FAR SOUTHERN MN WHERE LIMITED INSTABILITY
MAY ENHANCE RAINFALL RATES.

GLOBAL MODELS AND HI-RES MODELS ALIKE AGREED THAT THE PRECIP BAND
LOOKS TO MOVE OUT A BIT QUICKER ON THURSDAY. SO...DROPPED THE POPS
FASTER FROM WEST TO EAST EARLY TOMORROW THROUGH MID-MORNING. NOW
EXPECTING THE ENTIRE FA TO BE DRY BY LATE MORNING AND BEYOND.

OTHERWISE...TODAY WILL SEE STRONG SOUTHEASTERLY WINDS AHEAD OF THE
APPROACHING SYSTEM. INCREASED WINDS A FEW KNOTS AND HENCE THE
INCREASED HIGHS FOR TODAY SAW A SLIGHT INCREASE AS WELL.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 327 AM CDT WED OCT 22 2014

SHARP UPR LVL TROF WILL SHIFT OFF TO THE E THU EVE WHILE AN UPR
TROF BUILDS OVER THE NRN PLAINS. THE SFC PRES PATTERN WILL REMAIN
FAIRLY BAGGY...GENERALLY WITH LITTLE DEFINITION TO IT. THAT
SAID...A PRONOUNCED S-SW FLOW WILL DEVELOP AT THE SFC STARTING
FRI AND LAST INTO THE WEEKEND. A WEAK SFC CDFNT FRONT...BUT MORE
LIKELY A SFC TROF...WILL SWING THRU THE REGION FRI BUT BE OF
LITTLE CONSEQUENCE ASIDE FROM A SMALL INCREASE IN CLOUD COVER
FOLLOWING THE CLEARING BEHIND THE DEPARTING AFOREMENTIONED TROF.
THE DEPARTURE OF THIS TROF WILL SPELL LARGE-SCALE RIDGING OVER THE
CENTRAL CONUS...SPREADING NWD INTO THE NRN PLAINS AND UPR MISS
RIVER VALLEY. THE INCRS IN H5 HEIGHTS WILL ALLOW FOR NOTICEABLE
WARMING FOR THE WEEKEND...INCLUDING HIGHS REACHING AND POSSIBLY
ECLIPSING THE 70-DEGREE MARK. THIS WARM-UP LOOKS TO LAST FOR JUST
SATURDAY AND SUNDAY...AS THE RIDGE WILL FLATTEN AND SHIFT EWD LATE
SUN INTO MON IN ADVANCE OF A MORE ORGANIZED STORM SYSTEM FOR THE
START OF NEXT WEEK. THOUGH THERE IS DECENT MODEL AGREEMENT ON THE
FORMATION OF A STORM SYSTEM IN THE LEE OF THE ROCKIES MONDAY...
SHIFTING NEWD INTO THE GREAT LAKES BY TUE...THERE IS SOME MODEL
DISAGREEMENT AS TO THE PLACEMENT AND SPEED OF THE SYSTEM. HAVE
INCLUDED POPS BUT NO HIGHER THAN 30-40 PERCENT ATTM. THERE IS ALSO
GROWING CONFIDENCE THAT FOLLOWING THIS SYSTEM WILL BE A COOLING OF
TEMPERATURES BACK DOWN TO SEASONABLE LEVELS FOR THE MIDDLE PORTION
OF NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 140 PM CDT WED OCT 22 2014

MAIN CONCERN FOR 18Z TAFS WAS TIMING SHOWERS IN THIS EVENING.
TIMED THINGS IN BASED ON THE HRRR AND OTHER HI-RES MODELS...WHICH
ARE IN GOOD AGREEMENT WITH EACH OTHER. TRIED NARROWING SHRA
WINDOW DOWN TO 3 OR 4 HOURS...WITH ONLY CHANGE IN TIMING BEING TO
SLOW DOWN THE ARRIVAL OF SHRA BY A COUPLE OF HOURS. WE WILL LIKELY
SEE ISO THUNDER WITH THE BAND OF SHRA...AS WE HAVE SEEN ACROSS
THE DAKOTAS TODAY...BUT COVERAGE/DURATION NOT EXPECTED TO BE ENOUGH
TO MENTION IN A TAF FOR NOW. MVFR CIGS WILL BEGIN TO EXPAND WITH
THE RAIN SHOWERS...WITH THE HRRR SHOWING CIGS COMING DOWN TO
BETWEEN 012 AND 020 WITH THE RAIN. SKIES WILL BE CLEARING OUT
PRETTY QUICK FROM THE WEST TONIGHT...WITH WINDS BACKING OFF
CONSIDERABLY. WILL HAVE TO WATCH FOR THE DEVELOPMENT OF FOG WEST
OF THE TWIN CITIES...WITH STC LOOKING TO HAVE THE BEST CHANCE OF
FOGGING IN THU MORNING.

KMSP...
IF ANYTHING...CURRENT TAF IS AN HOUR OR SO TO FAST WITH BRINGING
PRECIP IN THIS EVENING. CONFIDENCE IS HIGH IN THE SHRA IMPACTING
MSP TONIGHT...BUT LESS CONFIDENCE ON THE MVFR CIGS. MVFR CIGS MOST
LIKELY WITHIN THE RAIN BAND...BUT LESS CONFIDENCE IN IF THOSE CIGS
WILL CONTINUE FOR A TIME INTO THE EARLY MORNING WHEN THE RAIN
ENDS. AFTER THAT...NO WEATHER CONCERNS FOR THE REST OF THURSDAY.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS SSW AT 5-10KTS.
SAT...VFR. WINDS NW AT 10-15KTS.
SUN...CHC MVFR/-SHRA OVERNIGHT. WINDS SE AT 10-15KTS.

&&

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

$$

SHORT TERM...SPD
LONG TERM...JPC
AVIATION...MPG






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