000
FXUS63 KMPX 182110
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
410 PM CDT TUE JUN 18 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 408 PM CDT TUE JUN 18 2013

THE EXTENSIVE LOW CLOUD CEILINGS ACROSS EAST CENTRAL AND SOUTHEAST
MN AS WELL AS WEST CENTRAL WI CONTINUE TO LIFT AND SLOWLY BREAK UP
AT MID AFTERNOON. A CONTINUED TREND TO CLR-SCT CONDITIONS IS
EXPECTED ONCE DAYTIME HEATING SUBSIDES. A RATHER STRONG DEW POINT
BOUNDARY HAS FORMED THIS AFTERNOON ACROSS OUR FAR NORTHERN AND
EASTERN CWA. DEW POINTS AT 3 PM RANGED FROM AROUND 60 AT
CAMBRIDGE...WITH 32 AT BRAINERD...SIREN AND RICE LAKE. REALLY NOT
EXPECTING THE DRY AIR TO MAKE ITS WAY MUCH FURTHER SOUTH SINCE THE
SURFACE HIGH IS OVER UPPER MI AND DROPPING SLOWLY SE. SURFACE WINDS
WILL ALSO BECOMING LIGHT SE AS WELL. THIS LEADS TO THE POTENTIAL FOR
SOME FOG TONIGHT ACROSS CENTRAL MN THROUGH WEST CENTRAL WI WHERE
WIND SPEEDS WILL BE THE LIGHTEST. JUST PATCHY FOG IS EXPECTED AT
THIS TIME.

WEDNESDAY BRINGS A RETURN OF INSTABILITY INTO WESTERN AND SOUTHERN
MN DURING THE DAY. MOST SHORT RANGE SOLUTIONS SHOW SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY BY AFTERNOON ACROSS ABOUT THE WESTERN HALF
OF MN IN THE LOW LEVEL THETA-E GRADIENT. CHANCE POPS WERE CONFINED
TO THIS AREA WITH DRY WEATHER INDICATED FOR THE TWIN CITIES AND
AREAS ON EAST AND SOUTH. LOWS TONIGHT DROPPING INTO THE UPPER 40S
FROM LADYSMITH TO AUGUSTA WITH MIDDLE TO UPPER 50S ACROSS WESTERN
AND SOUTHERN MN. HIGHS ON WEDNESDAY RUNNING FROM THE MIDDLE 70S IN
WEST CENTRAL WI TO THE LOWER 80S NEAR THE SD BORDER.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 408 PM CDT TUE JUN 18 2013

SUMMER PATTERN WILL REMAIN IN PLACE THROUGH THE
WEEKEND...WITH CONTINUOUS CHANCES FOR SEVERE WEATHER AND FLOODING
RAINS. AN UPPER LEVEL RIDGE CURRENTLY OVER THE HIGH PLAINS OF
MONTANA WILL SLOWLY MIGRATE EASTWARD TOWARDS THE GREAT LAKES
REGION...WITH AN UPPER LEVEL LOW FORECAST TO TAKE ITS PLACE OVER THE
HIGH PLAINS. THIS WILL SET UP SOUTHWEST FLOW ACROSS THE UPPER
MIDWEST. AN AREA OF SURFACE LOW PRESSURE WILL LINGER ACROSS THE
EASTERN DAKOTAS...WITH MOISTURE RICH SOUTHERLY FLOW PERSISTING
ACROSS MINNESOTA AND WISCONSIN THROUGH THE WEEKEND. SEVERAL ROUNDS
OF SHOWERS AND THUNDERSTORMS WILL FORM ALONG A FRONTAL BOUNDARY THAT
IS FORECAST TO OSCILLATE ACROSS THE CWA. THE ECMWF IS FARTHEST SOUTH
WITH IS POSITION GENERALLY ALONG THE IA/MN BORDER...WHILE THE GEM IS
FARTHER NORTH ALONG THE I-94 CORRIDOR...AND THE GFS FARTHER NORTH
YET CLOSER TO THE INTERNATIONAL BORDER. THE MAIN DIFFERENCES ARE
LIKELY DUE TO THE CONVECTIVE PARAMETRIZATION OF THE LARGE SCALE
MODELS. CURRENT THINKING IS THE GFS IS NOT HANDLING THE CONVECTIVE
OUTFLOW BOUNDARY(S) SOUTHERN REINFORCEMENT OF THE WARM FRONT...AND
THEREFORE LEANED MORE HEAVILY ON THE GEM/ECMWF SOLUTION. PWAT VALUES
WILL BE IN THE 1.50 TO 2.00 INCH RANGE...WHICH IN NEAR THE 99TH
PERCENTILE WHEN COMPARED WITH CLIMATOLOGY. THE ANTICYCLONIC FLOW AT
300MB WILL SUPPORT CONVECTIVE OUTFLOW...SO A 72HR IR LOOP ENDING ON
SUNDAY SHOULD SHOW PLENTY OF DEEP CONVECTION DEVELOPING ACROSS THE
DAKOTAS...AND TRACKING EASTWARD DURING THE OVERNIGHT HOURS AS THE
LOW LEVEL JET VEERS WITH TIME. IN FACT USE THE LOW LEVEL JET SEEN IN
BOTH THE H925 AND H850 PLAIN VIEW MAPS OF PURE WIND...MOISTURE
TRANSPORT...AND THETA_E ADVECTION AS THE MAIN DIAGNOSTIC TOOL FOR
POPS. SEVERE WEATHER IS POSSIBLE...WITH MAINLY A HAIL AND WIND
THREAT AS MOST OF THE CONVECTION EXPECTED TO BE ELEVATED AT THE NOSE
OF THE LOW LEVEL JET. FLOODING IS ALSO POSSIBLE WITH THE GFS 18.12Z
RUN SHOWING 7 INCHES OF RUN TOTAL RAIN THROUGH THE EXTENDED PERIOD.
EVEN THOUGH THE PLACEMENT OF THIS IS LIKELY INCORRECT...THE FACT THE
MODELS ARE PRODUCING THIS MUCH RAINFALL IS CONCERNING.

LOOKING AHEAD...BOTH THE GFS AND ECMWF TRANSITION TO ZONAL FLOW FOR
NEXT WEEK...WHICH SHOULD LIFT THE PRECIP INTO CANADA AND BRING
SEASONABLY HOT AND HUMID WEATHER ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1225 PM CDT TUE JUN 18 2013

MVFR CEILINGS ARE SLOWLY BREAKING UP/LIFTING ACROSS EAST CENTRAL
AND SE MN AS WELL AS WEST CENTRAL WI. IT/S A SLOW GO WITH HIGH
AMOUNTS OF LOW LEVEL MOISTURE FROM THE RECENT RAIN AND A VERY
NEGATIVE CU RULE. KMSP/KRNH SHOULD BE SCT-BKN035 BY 21Z. THE
CONCERN TONIGHT IS THE POTENTIAL FOR FOG FROM KSTC THROUGH KRNH
AND KEAU UNDER THE RIDGE AXIS. THE WET SOIL ALONG THE HYDROLAPSE
INCREASING WITH HEIGHT ON THE NAM BUFKIT GAVE INCREASING
CONFIDENCE TO INCLUDE MVFR FOG IN THE 09Z-13Z TIME FRAME. ON
WEDNESDAY...THE LOW LEVEL FLOW WILL BECOME SE WITH SPEEDS
INCREASING TO 10-15 KNOTS...WITH THE HIGHER SPEEDS FROM KAXN TO
KRWF. SOME GUSTINESS WILL DEVELOP AS WELL BY LATE MORNING WITH
SPEEDS IN THE LOWER 20 KNOT RANGE. ANOTHER CONCERN WEDNESDAY
MORNING IS HOW MUCH SHOWER/THUNDERSTORM ACTIVITY WILL BE IN
PROGRESS. CONFIDENCE IS NOT HIGH AT THIS TIME WITH VARIOUS SHORT
TERM SOLUTIONS NOT REALLY SHOWING MUCH. HOWEVER...PARAMETERS ARE
IN PLACE ALONG THE DAKOTAS/MN BORDER FOR SOME ACTIVITY.

KMSP...CEILINGS SLOWLY LIFTING AND SCATTERING OUT THIS AFTERNOON
ALONG WITH AN EAST WIND UP TO 10 KNOTS. VFR TONIGHT AND WEDNESDAY.
SOME CONCERN THERE MAY BE A FEW SHOWERS/THUNDERSTORMS AROUND IN
THE LATE AFTERNOON ON WEDNESDAY...BUT CONFIDENCE IS NOT HIGH. A
BETTER CHANCE FOR PRECIPITATION HEADING THROUGH WEDNESDAY NIGHT.
LIGHT SOUTHEAST WINDS TONIGHT INCREASING TO 10-12 KNOTS WEDNESDAY
MORNING.

/OUTLOOK FOR KMSP/
WED NIGHT...VFR WITH CHC OF MVFR AND SHRA/TS. SE WINDS 5-10 KTS.
THU...VFR. CHC OF MVFR SHRA/TS. SSE WINDS 10 KTS.
FRI...VFR. CHC OF MVFR SHRA/TS. S WINDS 10-15 KTS.

&&

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

$$

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