Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 091050
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
550 AM CDT WED JUL 9 2014

.UPDATED FOR 12Z AVIATION DISCUSSION...
ISSUED AT 543 AM CDT WED JUL 9 2014

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT WED JUL 9 2014

EARLY MORNING IR IMAGERY OVERLAID WITH SURFACE OBS AND PRESSURE
ANALYSIS REVEALED A WEAK SURFACE TROUGH FROM THE ELBOW OF
MINNESOTA EXTENDING NORTHEAST UP THROUGH THE ARROWHEAD...WITH AN
AREA OF CLOUDS LOCATED ALONG IT. THESE CLOUDS EXHIBITED A WARMING
TREND ON SATELLITE...AND THE RADAR ECHOES HAVE DECREASED IN
COVERAGE AS WELL. THERE IS SOME QUESTION AS TO WHETHER OR NOT A
FEW AFTERNOON RAIN SHOWERS WILL DEVELOP FROM THIS MID LEVEL CLOUD
DECK.

FORECAST SOUNDINGS SHOW DEEP BOUNDARY LAYER MIXING BEYOND 800MB
THIS AFTERNOON...WITH A FAIRLY STOUT INVERSION ABOVE IT. THIS
MIXING DEPTH SEEMS REASONABLE GIVEN THE 09.00Z MPX RAOB...WHICH
ALSO SHOWED 0.74IN OF PWAT PUTTING THIS AIRMASS IN THE LOWER
25PERCENTILE FOR MOISTURE WHEN COMPARED TO THE SEASONAL AVERAGE
FOR MID JULY. IN ORDER TO GET A MORE ACCURATE DEPICTION OF THE
TEMPERATURE ADVECTION THIS AFTERNOON ONE HAS TO LOOK ABOVE THIS
MIXING LEVEL...AND INDEED THE 700MB TEMPERATURES SHOW A SLIGHT
WARMING TREND THIS AFTERNOON WITH NORTHERLY WINDS...WHICH SEEMS TO
IMPLY THAT THE SUBSIDENCE INVERSION SHOULD REMAIN IN TACT AND KEEP
ANY PRECIP FROM DEVELOPING THIS AFTERNOON. CLOUDS WILL FORM LATER
TODAY SIMILAR TO TUESDAY...BUT SHOULD LACK THE VERTICAL
DEVELOPMENT NECESSARY FOR MEASURABLE RAINFALL. THE 09Z RUN OF THE
HOPWRF HAS BACKED OFF THE ACCUMULATED PRECIP COMPARED TO THE 06Z
RUN. MEMBERS 2 AND 4 ARE COMPLETELY DRY...WITH 1 AND 3 MANAGING A
FEW SHOWERS MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER. THE
FACT THAT TWO OF THE THREE MEMBERS WITH DOUBLE MOMENT MICROPHYSICS
SCHEMES ARE DRY GIVES ADDED CONFIDENCE IN CONTINUING WITH THE DRY
FORECAST. ALSO...WENT ON THE WARMER SIDE OF GUIDANCE WITH HIGH
TEMPS SINCE WERE SHOWING ABOUT A DEGREE OF COOL BIAS...BUT SMOKE
FROM CANADA MAY LIMIT AFTERNOON HEATING. LOOKING AHEAD...SOUTHERLY
WINDS WILL DEVELOP LATE WEDNESDAY NIGHT AS THE SURFACE HIGH
MIGRATES TOWARD THE GREAT LAKES.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 350 AM CDT WED JUL 9 2014

THU WILL START OUT WITH A SHORTWAVE RIDGE AXIS SHIFTING THROUGH
WITHIN FAIRLY PROGRESSIVE FLOW ALOFT WHILE SFC HIGH PRES CENTERED
OVER THE CENTRAL GREAT LAKES STILL MAINTAINS A WRN EXTENT OVER THE
UPR MISS RIVER VALLEY. THIS RIDGING INFLUENCE WILL WANE AS THE DAY
PROGRESSES...ALLOWING SEVERAL SHORTWAVE TROUGH AXES WITHIN A MORE
ZONAL FLOW TO SLIDE THROUGH THE REGION. IN ADDITION...AT THE
SFC...A CDFNT WILL ORGANIZE OVER NRN PLAINS THU NIGHT INTO FRI.
PLENTY OF MOISTURE AND WARM AIR AHEAD OF THE FNT WILL MAKE FOR A
GOOD ENOUGH CONVECTIVE MIXTURE TO PROMOTE SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS FOR THU NIGHT INTO FRI. NOT SEEING THE
POTENTIAL FOR WIDESPREAD SEVERE WX WITH THIS SCENARIO DUE TO THE
LACK OF DECENT SUPPORT ALOFT AND THE ELONGATION OF THE SFC FRONT
BETWEEN TWO LOW PRES CENTERS /ONE IN THE CENTRAL PLAINS AND THE
OTHER WELL N IN CENTRAL CANADA/. ONCE THIS FRONT PASSES THRU...
THEN THERE LOOKS TO BE A BREAK IN THE ACTION FRI NIGHT AHEAD OF A
SLOW-MOVING POST FRONTAL TROUGH THAT WILL GRADUALLY SWING THRU THE
REGION SAT THRU SUN MRNG...IN CONJUNCTION WITH A CONGLOMERATE OF
LOW PRES CENTERS DEVELOPING IN THE LEE OF THE ROCKIES OVER THE
WEEKEND. THIS WILL SET OFF ANOTHER SEVERAL ROUNDS OF SCATTERED
SHOWERS/THUNDERSTORMS FOR LATE DAY SAT INTO SUN NIGHT. HOWEVER...
ONCE THIS POST-FRONTAL TROUGH EXITS...NOTICEABLY COOLER AND DRIER
HIGH PRES WILL DROP IN FROM NWRN CANADA AND SIT OVER THE N-CENTRAL
CONUS FOR THE EARLY PORTION OF NEXT WEEK. THIS COOL DOME OF HIGH
PRES WILL KEEP THE AREA DEVOID OF PRECIPITATION FOR THE FIRST PART
OF NEXT WEEK...AND ALSO MAKE FOR TEMPERATURES NEARLY 10 DEGREES
BELOW NORMAL FOR EARLY NEXT WEEK...AND POTENTIALLY LONGER. HIGHS
THRU SUN WILL GENERALLY RANGE FROM THE UPR 70S TO MID 80S...THEN
STARTING ON MON...WILL FALL TO THE UPR 60S TO LWR 70S FOR THE
FIRST HALF OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 543 AM CDT WED JUL 9 2014

HIGH PRESSURE WILL REMAIN IN CONTROL. A FEW AFTERNOON CLOUDS IN
THE 6-8KFT RANGE WILL TRAVERSE THE REGION. MEANWHILE...SMOKE FROM
THE CANADIAN FIRES COULD BRING REDUCED VISIBILITIES ACROSS WESTERN
MN...BUT ASIDE FROM A MILKY SKY CONDITIONS SHOULD REMAIN VFR.

KMSP...
NO NOTEWORTHY CONCERNS FROM THE GENERAL DISCUSSION.

/OUTLOOK FOR KMSP/
THU...VFR WITH MVFR/SH/TSRA POSSIBLE LATE. WINDS SSE AT 10G15KTS.
FRI...VFR WITH MVFR/SH/TSRA POSSIBLE. WINDS S AT 5G10KTS.
SAT...VFR. WINDS LIGHT AND VARIABLE.

&&

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

$$

SHORT TERM...JRB
LONG TERM...JPC
AVIATION...JRB






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