000
FXUS63 KMPX 121126
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
626 AM CDT SUN MAY 12 2013

.UPDATED FOR 12Z AVIATION DISCUSSION...
ISSUED AT 618 AM CDT SUN MAY 12 2013

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT SUN MAY 12 2013

EARLY MORNING WATER VAPOR IMAGERY TOGETHER WITH 500MB HEIGHTS AND
WINDS SHOWED AN AMPLIFIED UPPER LEVEL PATTERN WITH A RIDGE ALONG THE
ROCKY MOUNTAINS SANDWICHED BETWEEN THE LONGWAVE TROUGHS OVER THE
GREAT LAKES AND THE GULF OF ALASKA. AT THE SURFACE A 1026MB HIGH WAS
POSITIONED ALONG THE MN/DAKOTA BORDER...WITH NORTHWEST WINDS EAST OF
THIS RIDGE AXIS ACROSS MINNESOTA AND WISCONSIN. THE 00Z RAOBS FROM
BOTH KMPX AND KABR WERE VERY SIMILAR...EACH SHOWING A BOUNDARY LAYER
DEPTH ABOVE 800MB. HOWEVER KMSP HAD A SLIGHTLY COOLER AND MORE MOIST
PROFILE WITH STRONGER NORTHWEST WINDS. BASED ON THE MEAGER EASTWARD
PROGRESSION OF THIS AIRMASS...TRENDED TOWARDS A PERSISTENCE FORECAST
ONLY WITH LIGHTER WINDS...BUT STILL A WEST TO EAST TEMPERATURE
GRADIENT ACROSS THE REGION. MIXING DOWN THE H800 TEMPS OFF THE NAM
YIELD HIGH TEMPERATURES FOR SUNDAY RANGING FROM THE LOWER 60S IN FAR
WESTERN MINNESOTA...TO LOWER 50S IN FAR WESTERN WISCONSIN. ALSO
LOWERED DEWPOINTS INTO THE LOW TO MID TEENS DURING THE AFTERNOON
HOURS. THE DRY AIR...CALM WINDS...AND CLEAR SKIES WILL BE FAVORABLE
FOR RADIATIONAL COOLING. TEMPERATURES WILL FALL BELOW FREEZING
ACROSS MOST OF WISCONSIN...AND AS A RESULT HAVE ISSUED FROST/FREEZE
HEADLINES. DID NOT INCLUDE RUST/BARRON/POLK COUNTIES SINCE THEY HAVE
BEEN COOLER. FOR EXAMPLE...THE GROWING DEGREE DAYS AT LADYSMITH ARE
LESS THAN HALF (46) THAN AT DURAND (94). SO ALTHOUGH TEMPERATURES
WILL BE JUST AS COLD OR COLDER ALONG HWY 8 IN WISCONSIN DID NOT FEEL
A HEADLINE WAS NECESSARY THIS FAR NORTH.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 345 AM CDT SUN MAY 12 2013

GOOD CONSISTENCY IN THE MODELS CONTINUES WITH REGARDS TO TIMING
AND PLACEMENT OF SYNOPTIC FEATURES DURING THE LONGER RANGE. THE
DEW POINTS REMAIN AN ISSUE AS THEY HAVE FOR THE PAST SEVERAL DAYS
AND WERE LOWERED ONCE AGAIN USING VARIOUS MOS GUIDANCE PRODUCTS.

A BLEND OF GFS/SREF WAS USED FOR RAIN CHANCES ON MONDAY AS A WARM
FRONT MOVES EASTWARD ACROSS THE FA. THE NAM WAS BASICALLY DRY...
BUT THE REFLECTIVITY PRODUCT PAINTED A DIFFERENT PICTURE AND WAS
SIMILAR TO THE GFS/SREF WITH SOME SHOWERS SPREADING SOUTHEAST
ACROSS CENTRAL MN IN THE MORNING AND INTO WEST CENTRAL WI BY
AFTERNOON. IN THE WAKE OF THE WARM FRONT...WE ARE STILL LOOKING
AT A HOT DAY ON TUESDAY. 850MB TEMPERATURE PROGS FROM ALL SOLUTIONS
POINT TO 20-24C FROM THE TWIN CITIES ON SOUTHWEST. WE CONTINUED
WITH A FORECAST OF AROUND 90 TO THE LOWER 90S FOR THE AFOREMENTIONED
AREA WITH 80S TO THE NORTH AND EAST. MODEL SPECTRUM SHOWS
CONSIDERABLE SPREAD FOR THE TWIN CITIES WITH HIGHS RANGING FROM 75
ON THE MENLOW TO 97 ON THE 4KM NAM. MIX DOWN FROM 875 MB OFF THE
GFS SUPPORTS A 90-92 DEGREE FORECAST QUITE WELL. THE RECORD HIGH
FOR MSP ON TUESDAY IS 95 DEGREES SET IN 1932.

THERE ARE SEVERAL CONCERNS ON TUESDAY. FIRST... THE SYNOPTIC
HEALTH WATCH-WARNING NETWORK IS FLAGGING TUESDAY AS A POTENTIAL
HEAT STRESS DAY WITH A DRY TROPICAL AIRMASS. TUESDAYS HEAT FORECAST
IS SIGNIFICANT AS WE HAVE ONLY HAD ONE 80 DEGREE DAY IN THE TWIN
CITIES SO FAR THIS YEAR. THIS IS A QUICK HITTER AND THE BLAST OF
HEAT MAY CAUSE SOME PROBLEMS. ANOTHER CONCERN ON TUESDAY IS WITH
FIRE WEATHER. ADJUSTING THE SURFACE DEW POINTS DOWNWARD HAS
RESULTED IN MINIMUM AFTERNOON HUMIDITY NEAR 25 PERCENT ALONG AND
SOUTHWEST OF THE MN RIVER. SURFACE WINDS ARE FORECAST TO BE NEAR
20 MPH AS WELL IN THIS AREA...LEADING TO POTENTIAL RED FLAG
CONDITIONS. THESE TWO CONDITIONS ARE ALMOST MET AS WELL MONDAY
AFTERNOON IN SOUTHWEST AREAS OF THE MN CWA AS WELL.

A WEAK COOL FRONT WILL THEN MOVE THROUGH TUESDAY EVENING. WE HAVE
A SIGNIFICANT CAP IN PLACE WITH TEMPERATURES AROUND 11C AT 735 MB.
THE CAP WILL SLOWLY ERODE DURING THE LATE EVENING AND THE SMALL
CHANCE POPS FOR THE EAST AND SOUTHERN CWA STILL LOOK PRUDENT. IF
CONVECTION COULD GET BREAK THROUGH THE CAP...THEN WE COULD HAVE
SOME PROBLEMS PER SPC SWODY3.

HATS OFF TO THE DAY SHIFT ON ELIMINATING THE SMALL CHANCE POPS
THAT PLAGUED MUCH OF THE MID TO LATE WEEK PERIOD. THE TREND
TONIGHT WAS SIMILAR. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS
RETURN LATE IN THE WEEK/WEEKEND AS A LOW PRESSURE SYSTEM MOVES
INTO THE CENTRAL PLAINS ALONG WITH A WARM FRONT PUSHING INTO OUR
SOUTHERN FA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 618 AM CDT SUN MAY 12 2013

VFR CONDITIONS THROUGHOUT. LIGHT WINDS WILL INCREASE OUT OF THE
NORTHWEST TO AROUND 10KTS...WITH GUSTS NEAR 20KTS ACROSS WESTERN
WISCONSIN. WINDS WILL DECREASE AFTER SUNSET AND BECOME SOUTHERLY
BY MONDAY MORNING.

KMSP...
VFR CONDITIONS WITH INCREASING NORTHWESTERLY WINDS THIS MORNING.
GUSTS WILL SUBSIDE DURING THE EVENING...AND WINDS WILL BECOME
SOUTHERLY OVERNIGHT.

/OUTLOOK FOR KMSP/
MON...VFR. WINDS S AT 15G20KTS.
TUE...VFR. WINDS SSW AT 15G20KTS.
WED...VFR. WINDS NW AT 10KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...FROST ADVISORY FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ023-024-026.

     FREEZE WARNING FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ025-027-028.

&&

$$

SHORT TERM...JRB
LONG TERM...RAH
AVIATION...JRB