Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 120921
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
421 AM CDT SAT JUL 12 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CDT SAT JUL 12 2014

IT`S WARM AND MUGGY ACROSS THE FORECAST AREA THIS MORNING...BUT SO
FAR THE HEAVY RAIN HAS REMAINED JUST TO THE SOUTH AND WEST
ACROSS SD/NE/IA. THIS SHOULD CHANGE OVER THE NEXT SEVERAL HOURS AS
MORE ACTIVITY IS EXPECTED TO FORM FARTHER NORTHEAST...ACROSS
SOUTHERN MINNESOTA. THE DEWPOINTS ARE EXPECTED TO SLOWLY FALL
TODAY...BUT THERE WON`T BE A DRAMATIC CHANGE IN THE AIRMASS
LOCALLY UNTIL NORTHWEST FLOW DEVELOPS ON SUNDAY.

WELL YOU REALLY WOULDN`T KNOW IT...BUT THERE IS A SLOW MOVING COLD
FRONT CREEPING SOUTHEAST ACROSS MINNESOTA EARLY THIS MORNING.
TEMPS AND DEWPOINTS ACROSS PORTIONS OF NORTHERN MN ARE 5-15
DEGREES COOLER THAN THEY WERE AT THIS TIME FRIDAY MORNING. THE
WIDESPREAD THUNDERSTORMS OFF TO OUR SOUTH AND WEST ARE CLOSER TO
THE SURFACE WARM FRONT IN AN AREA OF GOOD MID-LEVEL WARM ADVECTION
AND FGEN. THERE ARE ALSO PWATS NEAR 2" AND GOOD 850-300MB
THICKNESS DIFFLUENCE ACROSS IA...SO THERE IS A LOT WORKING IN
FAVOR FOR HEAVY RAIN IN AREAS TO OUR SOUTH. THAT BEING
SAID...SOUTHERN MN SHOULD SEE A SLIGHT INCREASE IN 925-850MB
MOISTURE TRANSPORT LATE THIS MORNING WITH MORE OF A SOUTHWEST
ORIENTATION TO THE LOW LEVEL FLOW VECTORS /THEY`VE BEEN NEAR ZERO
OR NORTH MOST OF THE NIGHT/. THERE IS ALSO A WEAK SHORTWAVE AND PV
FEATURE LOCATED IN ND/SD EARLY THIS MORNING...WHICH IS RESPONSIBLE
FOR THE CONVECTION FROM PIERRE, SD BACK TOWARD THE BLACK HILLS.
THIS FEATURE SHOULD MAKE IT TO THE SD/MN BORDER BY AROUND
15Z...WHICH COULD THEN KICK OFF MORE THUNDERSTORMS LATE THIS
MORNING AND INTO THE AFTERNOON. IN THE MEANTIME...WE ARE ALREADY
SEEING ACTIVITY IN SD TRANSLATE FARTHER EAST AND APPROACH THE
STATE LINE...NOT TO MENTION A COUPLE SHOWERS AND ENHANCED CUMULUS
DEVELOPMENT GOING UP ALONG THE SLOW MOVING COLD FRONT IN
MINNESOTA. THE SIGNAL FOR WIDESPREAD HEAVY RAIN OR EVEN WIDESPREAD
RAIN ISN`T GREAT TODAY...BUT THERE IS STILL PLENTY OF MOISTURE
AROUND AND ENOUGH FORCING TO JUSTIFY 40-70% RAIN ACROSS THE
FORECAST AREA. WE ARE SIMPLY NOT EXACTLY SURE WHICH FORCING
MECHANISM WILL DOMINATE AND AT WHAT TIME. THE AVAILABLE CAM
GUIDANCE OVERNIGHT...DOES SUGGEST A COUPLE DISTINCT AREAS OF
CONVECTIVE INITIATION ACROSS THE FORECAST TODAY /ONE NORTH AND ONE
SOUTH/...BUT THERE IS CONSIDERABLE DIFFERENCES IN TIMING AND
PLACEMENT...SO IT IS DIFFICULT TO INCLUDE HIGHER THAN 70-75%
CHANCE OF RAIN AT ANY ONE LOCATION GIVEN THE UNCERTAINTY. THUNDER
DOES SEEM MUCH MORE LIKELY ACROSS SOUTHERN MN WHEN COMPARED TO
WHAT IS EXPECTED IN CENTRAL MN AND EVEN WEST CENTRAL MN.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 248 AM CDT SAT JUL 12 2014

THE PERIOD WILL BEGIN WITH A CDFNT HAVING JUST SANK TO THE S OF
THE MPX CWFA...AND THIS WILL BEGIN THE POTENT CAA ADVERTISED FOR
THE N-CENTRAL CONUS OVER THE PAST SEVERAL DAYS. WHILE THE CDFNT
DROPS FURTHER S AND E DURG THE DAY SUN AND SUN NIGHT...A DEEP UPR
LVL CUTOFF LOW WILL DROP S FROM CENTRAL CANADA INTO THE GRT LKS
SUN NIGHT INTO MON. THERE WILL BE ENOUGH SEPARATION BETWEEN BOTH
FEATURES SUCH THAT A DRY DAY ON SUN FOR THE ENTIRE CWFA LOOKS IN
ORDER. HOWEVER...AS THE UPR LOW NEARS...SEVERAL SHTWV TROUGH AXES
WILL ROTATE ARND THE WRN FRINGES OF THE UPR LOW. IN ADDITION...A
WEAK POST-FRONTAL SFC TROUGH WILL ALSO DROP THRU THE REGION ON
MON...ALLOWING FOR SCATTERED RAIN SHWRS TO DEVELOP ACRS THE AREA.
AS THE UPR LOW PULLS AWAY FROM THE AREA MON NIGHT INTO TUE...THE
POTENTIAL FOR PRECIP WILL ALSO SHIFT OFF TO THE E. THUS LEAVING
THE MAIN STORY TO BE THE DROP IN TEMPERATURES. H85 TEMPS STILL
LOOK TO DROP TO THE 4 TO 6 DEG C RANGE...WELL BELOW NORMAL FOR
MID-JULY...AND THIS WILL TRANSLATE TO SFC TEMPS ARND 15 DEGREES
BELOW NORMAL. THE COLDEST AIR WILL DROP THRU THE REGION SUN NIGHT
THRU TUE NIGHT...WHERE HIGHS WILL ONLY HIT THE 60S WITH LOWS AS
FAR DOWN AS THE LWR 50S AND POTENTIALLY SOME UPR 40S IN NORMALLY
COLDER LOCATIONS. TEMPS DO LOOK TO MODERATE GOING INTO THE MID-TO-
LATE WEEK PERIOD AND THIS WILL BE ACCOMPANIED BY EXTENSIVE HIGH
PRES THAT WILL KEEP PRECIP AWAY FROM THE REGION STARTING TUE
NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1103 PM CDT FRI JUL 11 2014

LOW CONFIDENCE FORECAST OVERNIGHT WITH RESPECT TO THE IFR
CEILING/VSBY POTENTIAL AT KRNH AND KEAU. THE COLD FRONT NEAR AN
KAXN TO KHON LINE HAS HARDLY MOVED THIS EVENING IN RESPONSE TO A
WAVE OF LOW PRESSURE DEVELOPING ON THE TAIL END OF THE FRONT. A
FEW TSRA CONTINUE TO MOVE SE OF KJMR. THESE SHOULD DISSIPATE WHILE
PASSING JUST NE OF KRNH. WITH THE FRONT NEARLY STALLING...THIS HAS
KEPT LOW VFR CLOUDINESS FROM SE MN THROUGH WEST CENTRAL WI FROM
BEING PUSHED EAST. THERE IS STILL A WINDOW OF OPPORTUNITY LATE IN
THE NIGHT FOR THIS CLOUDINESS TO BREAK UP SOME...ALLOWING FOG AND
STRATUS CEILINGS TO FORM. HOWEVER...MORE MID/HIGH LEVEL CLOUDS ARE
ALREADY FILTERING INTO WESTERN MN FROM CONVECTION IN THE WESTERN
HIGH PLAINS. THEREFORE...MODIFIED MAINLY THE LOW VISIBILITY
FORECAST AT KRNH AND KEAU DUE TO MORE HIGHER LEVEL CLOUDINESS BUT
HELD ON TO THE LOW CEILING FORECAST. KMSP...KSTC AND KRWF ARE
BETTER SUITED FOR MVFR FOG ALMOST RIGHT OUT THE GATE...BUT
AGAIN...THE INCREASING MID/HIGH LEVEL CLOUDS SHOULD TEMPER ON HOW
LOW VSBYS GO. HELD ON TO MVFR CIGS FOR A TIME SATURDAY MORNING AT
KRNH AND KEAU AS THE WAVE OF LOW PRESSURE RIDES NORTHEAST ALONG
THE FRONT. SHOWERS AND ISOLATED THUNDERSTORM WILL SPREAD INTO WEST
CENTRAL AND SOUTHERN MN BEFORE DAYBREAK SATURDAY AND PERSIST
THROUGH MUCH OF THE DAY. KRWF SHOULD SEE SCATTERED SHOWERS BUT
MVFR CONDITIONS ARE FORECAST TO REMAIN SOUTH OF THIS SITE. LIGHT
WINDS OVERNIGHT TONIGHT WITH NORTHWEST TO WEST WINDS LESS THAN 10
KNOTS ON SATURDAY.

KMSP...CONFIDENCE LOW ON THE CEILING/VSBY FORECAST OVERNIGHT.
CERTAINLY SEEMS TO BE HIGH POTENTIAL FOR LOW CONDITIONS DEVELOPING
WITH A VERY MOIST LOW LEVEL PROFILE IN PLACE. THE QUESTION IS
WHETHER THE INCREASING MID/HIGH LEVEL CLOUDS FROM THE WEST
OVERRULE AND KEEP THINGS VFR. IN KEEPING WITH THE LOW CEILINGS...
HELD ON TO MVFR CEILINGS INTO MID MORNING AS THE COLD FRONT
MOVES THROUGH. A RATHER ORGANIZED AREA OF SHOWERS WILL BE JUST
SOUTH OF THE AIRFIELD BY MIDDAY SATURDAY AND PERSIST THROUGH THE
AFTERNOON. VCSH USED AT THIS POINT.

/OUTLOOK FOR KMSP/
SUN...VFR. NW WINDS 10-15 KTS.
MON...MVFR PSBL WITH CHC OF SHRA/TSRA. NW WINDS 15-25 KTS.
TUE...VFR. NW WINDS 10-15 KTS.

&&

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

$$

SHORT TERM...CLF
LONG TERM...JPC
AVIATION...RAH






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