105 
FXUS63 KMPX 190826
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
326 AM CDT FRI MAR 19 2010

.DISCUSSION...

MUCH COOLER...BUT MORE SEASONABLE...AIR IS ON THE WAY TO THE 
FORECAST AREA TODAY AND SATURDAY WITH A MODEST UPWARD TREND IN 
TEMPERATURES FROM SUNDAY INTO THE MIDDLE OF NEXT WEEK. 
OVERALL...PRECIP CHANCES WILL BE MINIMAL THROUGH THE PERIOD THOUGH 
THERE WILL BE CHANCES RETURNING BY THE MIDDLE OF NEXT WEEK. EARLY 
MORNING WATER VAPOR IMAGERY SHOWS AN UPPER CIRCULATION SPINNING 
ACROSS NORTH-CENTRAL ONTARIO WITH A LOW AMPLITUDE TROUGH AXIS 
EXTENDING BACK TO THE SOUTHWEST ACROSS THE DAKOTAS. A STRONGER 
CIRCULATION IS SEEN ON THE TAIL EDGE OF THIS TROUGH MOVING INTO 
WESTERN ARIZONA. THIS LOW WILL TRACK EASTWARD ACROSS THE SOUTHERN 
PLAINS INTO SUNDAY AND EVOLVE INTO A LARGE CLOSED LOW. THIS WILL 
RESULT IN A QUIET FLOW PATTERN FOR THE LOCAL AREA FOR THE WEEKEND 
WITH SFC HIGH PRESSURE IN PLACE.

SOME DETAILS...APPROACH OF AFOREMENTIONED UPPER TROUGH AXIS WILL BE 
THE FOCUS IN THE NEAR TERM. MID LEVEL BAROCLINIC ZONE IS RATHER 
TIGHT WITH THE PUSH OF COLD AIR. FRONTOGENETICAL FORCING ASSOCIATED 
WITH THIS TEMPERATURE GRADIENT CONTINUES TO GENERATE BANDS OF RADAR 
RETURNS REPRESENTING SPRINKLES AND SPOTTY LIGHT RAIN FROM SOUTHEAST 
SODAK ACROSS SOUTHERN MN INTO WESTERN WI WITH LITTLE ACTUALLY 
REACHING THE GROUND THANKS TO RATHER DRY LOW LEVEL MOISTURE 
PROFILES. THE BAROCLINIC ZONE WILL TIGHTEN TO THE SOUTHWEST AS THE 
ARIZONA UPPER LOW MOVES ACROSS THE FOUR CORNERS THIS MORNING HELPING 
PUSH DEVELOPING SFC INVERTED TROUGH ACROSS SE COLORADO EASTWARD INTO 
THE HIGH PLAINS. FORCING ASSOCIATED WITH THIS SYSTEM MAY BE ABLE TO BE 
ENHANCED AS FAR NORTH AS THE FAR SOUTHERN CWA THIS MORNING RESULTING 
IN A BETTER CHANCE FOR RAIN OR SNOW OR A MIX OF THE TWO. MODELS HAVE 
BEEN TRENDING FURTHER AND FURTHER SOUTH WITH FORCING/MOISTURE FOR 
PRECIP WITH LATEST RADAR TRENDS SUPPORTING THIS BUT THE FAR SOUTHERN 
CWA LOOKS TO BE AFFECTED. WILL MAINTAIN LOW CHANCE MENTION OF 
RAIN/SNOW ACROSS THE SOUTHERN TWO TIERS OF MN COUNTIES THROUGH THE 
DAY. ELSEWHERE...MOSTLY CLOUDY TO PARTLY SUNNY SKIES WILL BE THE 
RULE AS COLDER AIR SETTLES IN. ENOUGH FGEN REMAINS PRESENT TO KEEP 
THE SPRINKLES GOING AND ENOUGH COLD AIR WILL FILL IN TO TURN THEM TO 
FLURRIES IN THE NEXT FEW HOURS. H85 TEMPS ARE IN THE PROCESS OF 
CRASHING FROM +3 TO +6 TO BETWEEN -8 AND -10 C AND COMBINED WITH THE 
CLOUD COVER WILL ONLY SUPPORT HIGHS IN THE LOWER 30S WEST TO AROUND 
40 EAST. STEEP LOW LEVEL LAPSE RATES WILL BE PRESENT SUGGESTING 
ADDITIONAL FLURRY POTENTIAL IN THE COLDER AIR FOR MUCH OF THE AREA 
INTO THE AFTERNOON BUT CYCLONIC FLOW BECOMES ANTICYCLONIC BY EARLY 
AFTERNOON WHICH SHOULD LIMIT DEVELOPMENT. NORTHWEST BREEZES OF 15 TO 
25 MPH WILL KEEP THINGS BRISK WITH GUSTS TO AROUND 30 MPH IN THE FAR 
WEST. 

HIGH PRESSURE WILL MOVE SOUTHWARD ALONG THE LEE OF THE ROCKIES 
TONIGHT BRINGING A DECREASED PRESSURE GRADIENT AND LIGHTER WINDS. 
CLOUDS WILL REMAIN INTO THE EVENING BUT MAY CLEAR OUT EVEN BEFORE 
DAYBREAK SATURDAY. THE WIND SHOULD HELP KEEP TEMPS FROM BOTTOMING 
OUT BUT LOWS WILL STILL FALL INTO THE 20S. SATURDAY WILL STILL BE 
COLD WITH LITTLE CHANGE IN THE TEMPERATURE PROFILE PLUS THE SFC 
RIDGE AXIS WILL BE MOVING OVERHEAD. HIGHS SIMILAR TO TODAY ARE 
EXPECTED BUT LIGHTER WINDS AND SUNSHINE WILL ACCOMPANY THEM. THE 
MAIN BELT OF MID/UPPER LEVEL FLOW WILL REMAIN TO THE NORTH OF THE 
AREA INTO SUNDAY WITH WEAK UPPER RIDGING NOSING IN FROM THE WEST BY 
MIDDAY SUNDAY. SATURDAY NIGHT WILL BE QUITE COLD AGAIN THANKS TO THE 
SFC HIGH ...WITH MANY SITES DROPPING INTO THE TEENS BUT TEMPS SHOULD 
QUICKLY RECOVER SUNDAY AS WARM ADVECTION COMMENCES. SFC FLOW WILL 
STILL BE LIGHT WHICH MAY INHIBIT MIXING WHICH WILL MAKE TEMPS A 
CHALLENGE. GUIDANCE SHOWS A RANGE OF TEMPS BUT THE MAJORITY ARE ON 
THE WARMER END INDICATING 50 OR BETTER FOR MOST OF THE AREA. WILL 
ADD A FEW MORE DEGREES TO THE PREVIOUS FORECAST PUSHING HIGHS TO THE 
UPPER 40S WITH A FEW 50S AS WELL. WOULDN/T TAKE MUCH TO HAVE THINGS 
GO EVEN WARMER BUT THE COLD START AND THE WEAK SFC FLOW WOULD BE THE 
LIMITING FACTOR SO WILL STICK WITH AN INCREMENTAL INCREASE FOR NOW. 
MONDAY LOOKS WARMER STILL WITH QUIET WEATHER CONTINUING AND SLIGHT 
UPPER RIDGING ALOFT BUT BROAD TROUGHING WILL BE DEVELOPING OVER THE 
WESTERN U.S. WITH SFC LOW PRESSURE DEVELOPING IN THE LEE OF THE 
NORTHERN ROCKIES BY MONDAY NIGHT. MODELS BEGIN TO DIVERGE HERE WITH 
THE GFS PUSHING THE LOW ACROSS MINNESOTA MORE QUICKLY THAN THE ECMWF. 
A SLOWER APPROACH WOULD LIKELY RESULT IN MUCH WARMER TEMPS FOR 
TUESDAY WITH THE ECMWF ADVERTISING +8 C OR BETTER AT H85 WITH DRY 
WEATHER CONTINUING. WILL KEEP THE SLIGHT CHANCE POPS GOING FOR 
TUESDAY INTO WEDNESDAY FROM THE PREVIOUS FORECAST GIVEN THE 
DIFFERENCE IN SOLUTIONS.  ..MDB..


&&

.AVIATION.../06Z TAF ISSUANCE/ 
COLD FRONTAL PASSAGE WILL DRAW IN MVFR CLOUDS AND GUSTY NORTHWEST
WINDS OVERNIGHT. GUIDANCE HAS A DECENT HANDLE ON THINGS...AND
BRINGS BKN-OVC CIGS AROUND 2500 FT IN OVERNIGHT THROUGH FRIDAY
MORNING. GRADUAL IMPROVEMENT SHOULD OCCUR AFTER 18Z FROM NORTH TO
SOUTH ACROSS THE TAF SITES. 

KMSP...OVERCAST MID LEVEL DECK TO START OFF THE PERIOD...THEN SCT
CLOUDS AROUND 2500 FT SHOULD ARRIVE AROUND 09Z. MVFR DECK BECOMES
BROKEN AROUND DAYBREAK. NORTHWEST WINDS GUSTING INTO THE MID/UPPER
TEENS /KNOTS/ OVERNIGHT...THEN GUSTS UP TO 25 KTS POSSIBLE ON
FRIDAY. SCATTERING OF THE MVFR DECK IS EXPECTED AROUND/AFTER
21Z...WITH WINDS DECREASING BELOW 10 KTS AFTER 02Z.



&&

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

$$

MDB/LS