National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KMPX 141133
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
633 AM CDT TUE MAY 14 2013

.FIRE WEATHER...
ISSUED AT 440 AM CDT TUE MAY 14 2013

A RED FLAG WARNING NOW COVERS ALL OF OUR MN COUNTIES FOR THIS
AFTERNOON AND EARLY EVENING. A DRY SURGE OF HEAT WILL OCCUR TODAY
WITH AFTERNOON HUMIDITY VALUES LOWERING TO A FEW PERCENT ABOVE AND
BELOW 20. THE VERY LOW HUMIDITY COUPLED WITH SOUTHWEST TO WEST
WINDS FROM 20 TO 25 MPH ...WITH GUSTS TO 35 MPH... COULD LEAD TO
DANGEROUS WILDFIRE CONDITIONS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 440 AM CDT TUE MAY 14 2013

THERE ARE MANY CONCERNS TODAY AS A LOW PRESSURE SYSTEM AND COLD
FRONT MOVE ACROSS THE FA DURING THE AFTERNOON AND EVENING. A SMALL
COMPLEX OF THUNDERSTORMS DID DEVELOP OVER NORTH DAKOTA OVERNIGHT AS
EXPECTED. THIS AREA OF PRECIPITATION WILL ADVANCE ACROSS NORTHERN
MN THIS MORNING. CONSENSUS FROM THE WRF MODELS WAS LITTLE
(SPRINKLES) OR NOTHING REACHING DOWN INTO CENTRAL MN OTHER THAN
SOME CLOUDS. BY LATE MORNING...THE LOW AND COLD FRONT SHOULD BE
INTO FAR WESTERN AREAS OF MN. SOUTH TO SOUTHWEST WINDS WILL INCREASE
AHEAD OF THE FRONT WHILE RATHER STRONG WEST/NORTHWEST WINDS OCCUR
IN THE WAKE OF THE FRONT. A LOW LEVEL THERMAL RIDGE WILL ADVANCE
NORTHEAST FROM THE CENTRAL PLAINS AND REACH INTO THE TWIN CITIES
BY LATE IN THE AFTERNOON. THE SHORT TERM MODELS REMAIN CONSISTENT
ON 23-26 DEG C AIR AT 850MB FROM THE TWIN CITIES ON SOUTHWEST INTO
NORTHERN IA RESPECTIVELY. HIGHS RECENTLY TO OUR WEST AND NORTHWEST
(CANADA) HAVE BEEN RUNNING REAL CLOSE TO 20 DEGREES ABOVE THESE
CONVERTED VALUES. THIS WOULD YIELD HIGHS FROM 93 TO 99 DEGREES.
AS A RESULT... OUR CURRENT FORECAST WAS RAISED A FEW DEGREES...
ESPECIALLY ACROSS SOUTH CENTRAL MN... WHERE THE RAP SOUNDINGS WERE
SHOWING HIGHS OF 100-103. THIS ALSO RESULTED IN A RECORD HIGH BEING
FORECAST FOR THE TWIN CITIES.

THE HEAT TODAY HAS LEAD TO THE ISSUANCE OF A HEAT ADVISORY FROM
THE TWIN CITIES ON SOUTH AND SOUTHWEST TO ALBERT LEA AND REDWOOD
FALLS. THIS IS A DRY HEAT BEING ACCOMPANIED BY 20 TO 25 MPH WINDS
DURING THE AFTERNOON... WHICH MAY LEAD TO DEHYDRATION ISSUES FOR
THOSE WORKING OUTSIDE. ANOTHER IMPORTANT ISSUE IS THAT THE TWIN
CITIES HAS ONLY BEEN IN THE 80S ONCE SO FAR THIS YEAR WITH 81
DEGREES ON APRIL 28TH. THIS BURST OF HEAT MAY LEAD TO HEALTH
ISSUES.

ANOTHER CONCERN TODAY IS THE POTENTIAL FOR WIND ADVISORY CRITERIA
BEING MET IN THE NORTHWEST CWA IN THE MID TO LATE AFTERNOON HOURS.
THE RAP LOW LEVEL WINDS IN THE 200-300 FOOT RANGE ARE FORECAST IN
THE UPPER 20 KNOT RANGE. THIS IS THE HIGHEST OF ALL THE GUIDANCE.
THE NAM WINDS WERE MORE IN THE 23-24 KNOT RANGE WHICH BLENDED WELL
WITH THE LAMP GUIDANCE. CRITERIA FOR A WIND ADVISORY HAS A BETTER
CHANCE OF BEGIN MET OVER NORTH DAKOTA. AT THIS POINT WE HELD OFF
ON ISSUING AN ADVISORY.

FINALLY...ALTHOUGH A STRONG CAP EXISTS IN THE 700-750MB RANGE
TODAY...THERE REMAINS SOME POTENTIAL FOR CONVECTION TO BREACH THE
CAP AND DEVELOP DURING THE LATE AFTERNOON/EVENING ALONG THE
FRONT... MAINLY TO THE EAST AND SOUTH OF THE TWIN CITIES. WE KEPT
THE SMALL CHANCES FOR THUNDERSTORMS AS IS. OUR LOCAL WRF WAS THE
MOST AGGRESSIVE WITH ACTIVITY DEVELOPING FROM JUST SOUTH OF THE
TWIN CITIES TO OMAHA AROUND 21Z...WHILE THE NMM WRF HAS SOME
STORMS JUST EAST OF US. MOST OF THE SOLUTIONS SHOW A HIGHER CHANCE
FOR STORMS OVER IA TONIGHT AS WELL AS IN NORTHEAST WI. GIVEN THE
SHEAR FORECAST...STORMS THAT DO DEVELOP COULD BECOME SEVERE WITH
LARGE HAIL AND DAMAGING WINDS... ESPECIALLY WITH THE INVERTED V
SOUNDING. NAM DOWNDRAFT CAPE VALUES ARE ON THE ORDER OF 1000 J/KG
OVER WEST CENTRAL WI AND SE MN LATE THIS AFTERNOON AND EVENING.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 415 AM CDT TUE MAY 14 2013

WEDNESDAY THROUGH MONDAY...QUIET AND SEASONABLE WEATHER WILL GIVE
WAY TO A WETTER PATTERN AT THE END OF THE PERIOD. SEVERE WEATHER IS
ALSO POSSIBLE FOR THE WEEKEND. EARLY MORNING NORTHERN HEMISPHERIC IR
IMAGERY TOGETHER WITH THE ECMWF 250MB HEIGHTS AND WINDS IDENTIFIED
ZONAL FLOW ACROSS THE WESTERN CONUS...WITH A LOW AMPLITUDE PATTERN
ACROSS THE PACIFIC. FOR WEDNESDAY AND THURSDAY THIS ZONAL FLOW WILL
SET UP ACROSS INTERNATIONAL BORDER...WITH NEGATIVE VORTICITY
ADVECTION AND WEAK SUBSIDENCE ACROSS THE UPPER MIDWEST. THIS WILL
RESULT IN TWO DRY DAYS WITH LIGHT WINDS AND TEMPERATURES 5 TO 10
DEGREES ABOVE THE SEASONAL AVERAGE FOR MID MAY.

BY THURSDAY NIGHT THE AFOREMENTIONED LOW AMPLITUDE JET ACROSS THE
PACIFIC WILL BEGIN TO DIG ACROSS THE WESTERN US...WITH A BROAD AREA
OF LEE SIDE TROUGHING ALONG THE EASTERN SPINE OF THE ROCKIES. THIS
WILL INDUCE SOUTHERLY FLOW WITH GULF MOISTURE TRANSPORT ACROSS THE
CENTRAL CONUS...AND GRADUALLY BUILD AN UPPER LEVEL RIDGE THURSDAY
NIGHT INTO FRIDAY. MEANWHILE THE COLD FRONT THAT WILL HAVE PASSED
THROUGH THE AREA ON TUESDAY AND STALL OUT ACROSS SOUTHERN IOWA WILL
LIFT NORTHWARD AS A WARM FRONT. LOW LEVEL THETA_E ADVECTION AS SEEN
IN THE H925-850 LAYER SHOULD PROMOTE THUNDERSTORM DEVELOPMENT ALONG
THE WARM FRONT...WHILE THE UPPER LEVEL ANTICYCLONIC FLOW ALOFT
ALLOWS EVACUATES THE OUTFLOW FROM THESES STORMS AND ALLOWS THEM TO
PERSIST. DIFFICULT TO QUANTIFY THE CONVECTIVE POTENTIAL SINCE THE
LOW LEVEL MOISTURE HAS BEEN UNRELIABLE LATELY. HOWEVER...THE
SYNOPTIC SETUP WITH GULF MOISTURE ADVECTION INCREASES CONFIDENCE
THAT THESE MOISTURE DEPENDENT VARIABLES...A.K.A. CAPE...ARE
REASONABLY REPRESENTED. DEEP LAYER SHEAR PROFILES VARY DEPENDING ON
THE TIMING AND PLACEMENT OF THE WARM FRONT...BUT BOTH THE 14.12 GFS
AND ECMWF ARE IN GOOD AGREEMENT AND LIFT THE FRONT THROUGH THE CWA
ON FRIDAY. MEANWHILE THE UPPER LEVEL JET WILL CONTINUE TO CARVE OUT
A TROUGH OVER THE FOUR CORNERS REGION. THE GFS...GEM...AND ECMWF ALL
DEVELOP A SURFACE LOW AND TRACK IT ACROSS THE UPPER MIDWEST FOR THE
WEEKEND...BRINGING CONTINUED CHANCES FOR PRECIP. THE RUN TOTAL
PRECIP FROM THE GFS AND ECMWF INDICATE THAT OVER 3 INCHES OF RAIN
ARE POSSIBLE. WITH THIS PROLONGED PERIOD OF PRECIP. IN
SUMMATION...EXPECT AN MCS TO DEVELOP THURSDAY NIGHT AND MOVE ACROSS
THE REGION FRIDAY AS THE WARM FRONT LIFTS NORTHWARD. THEN WILL SEE
CONTINUES CHANCES FOR THUNDERSTORMS SATURDAY AND SUNDAY AS THE UPPER
LEVEL DYNAMICS BECOME MORE FAVORABLE FOR ASCENT. SEVERE WEATHER
REMAINS POSSIBLE...BUT CONFIDENCE IN THE EXACT PLACEMENT OF THE
MESOSCALE FEATURES IS LOW AT THIS TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 548 AM CDT TUE MAY 14 2013

A COLD FRONT ACROSS THE EASTERN DAKOTAS WILL MOVE INTO WESTERN MN
BY 15Z. THE FRONT SHOULD REACH THE TWIN CITIES AROUND 22Z AND PASS
KEAU BY 15/02Z. SOME STORMS HAVE DEVELOPED ALONG THE FRONT THIS
MORNING AND WILL BE PASSING THROUGH KAXN THROUGH 15Z. GUSTY WINDS
TO 40 KNOTS MAY OCCUR WITH THESE STORMS. THE ACTIVITY IS EXPECTED
TO WANE DURING THE MORNING AS A MID LEVEL CAP DEVELOPS. THIS
SHOULD HOLD OFF CONVECTION OVER EASTERN AREAS FOR MUCH OF THE
AFTERNOON... BUT BY 22Z OR SO SEVERAL WRF MODELS ARE HINTING AT
STORMS DEVELOPING JUST SOUTH AND EAST OF KMSP. THE SITE WITH THE
GREATEST RISK FOR SEEING A STORM IS KEAU AND A PROB GROUP FOR TSRA
REMAINS. ANOTHER CONCERN TODAY IS THE WIND. THE PREVIOUS TAF
FORECASTS HAD THIS HANDLED WELL AND LITTLE CHANGE WAS MADE.
INITIALLY S TO SW WINDS WILL INCREASE AHEAD OF THE FRONT TO 15
KNOTS WITH GUSTS INTO THE 20-25 KNOT RANGE AND THEN BECOME W TO NW
WITH FROPA NEAR 20 KNOTS WITH GUSTS TO NEAR 30 KNOTS. THE WIND
WILL THEN DIMINISH DURING THE EVENING.

KMSP...SOUTH WINDS (180-200) INCREASING TO 12 KNOTS WITH GUSTS 18
KNOTS BY 16Z THEN BECOMING MORE SW FOR THE AFTERNOON (210-230)
WITH A FURTHER INCREASE TO 15-20 KNOTS. GUSTS AROUND 25 KNOTS WILL
ALSO OCCUR. WEST WINDS AROUND 20 KNOTS FOR THE LATE
AFTERNOON/EVENING PUSH. GUSTS WILL CONTINUE. THERE IS ALSO A
THREAT FOR STORMS TO DEVELOP...BUT AT THIS TIME THEY ARE EXPECTED
TO BE EAST AND SOUTH OF THE AIRFIELD. DIMINISHING WIND AFTER 15/03Z.

/OUTLOOK FOR KMSP/

WED...VFR. NW WINDS 10 KTS.
THU...VFR. LGT AND VRBL WINDS.
FRI...VFR WITH MVFR/-TSRA POSSIBLE. SE WINDS 10 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
     MNZ041>045-047>070-073>078-082>085-091>093.

     HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
     MNZ059>063-065>070-073>077-082>085-091>093.

WI...NONE.
&&

$$

FIRE WEATHER...RAH
SHORT TERM...RAH
LONG TERM...JRB
AVIATION...RAH