Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 222046
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
346 PM CDT TUE APR 22 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 346 PM CDT TUE APR 22 2014

HIGH PRESSURE CENTERED OVER EASTERN MN THIS AFTERNOON WILL
CONTINUE TO MAKE SLOW BUT STEADY PROGRESS EAST OVERNIGHT AS A
LARGE STORM SYSTEM MOVES INTO THE INTER-MOUNTAIN WEST. AN UPPER
LEVEL RIDGE AXIS WILL LAG THE SFC RIDGE TONIGHT...KEEPING THE AREA
DRY UNTIL EARLY MORNING (~12Z). SE WINDS WILL DEVELOP ON THE BACK
SIDE OF THE HIGH ALSO HELPING TO KEEP THE PRECIP AT BAY AS IT
CONTINUES TO ADVECT IN LOWER DEWPOINTS (ESPECIALLY IN FAE E MN AND
W WI). DESPITE THESE CHALLENGES...MY EXPERIENCE IS THAT PRECIP
DEVELOPS QUICKER... OVERCOMING DRY LOW LEVEL AIR IN WARM ADVECTION
CASES LIKE THIS ONE. LOW PRESSURE DEVELOPS IN MONTANA OVERNIGHT
WITH A WARM FRONT STRETCHING INTO E SD LATE. WARM ADVECTION ALONG
THE FRONT WILL BE THE PRIMARY DRIVER FOR PRECIP GENERATION ALONG
WITH AN INITIAL SHORTWAVE ROUNDING THE BASE OF THE WESTERN TROUGH.
A BAND OF RAIN SHOULD EXPAND ALONG THE FRONT IN THE EASTERN
DAKOTAS LATE AND MOVE ACROSS MN DURING THE MORNING AND EARLY
AFTERNOON. POPS HAVE BEEN DRAWN TO REFLECT THIS BAND OF RAIN
MOVING ACROSS THE CWA DURING THE DAY. ANY INSTABILITY IS PROGGED
TO REMAIN SOUTH OF THE DEVELOPING LOW PRESSURE CENTER ALONG A COLD
FRONT...WHICH WOULD PLACE ANY T-STORM THREAT IN S SD/NEB AND IOWA.
I AM NOT COMPLETELY RULING OUT A RUMBLE OF THUNDER AS THE BAND OF
ELEVATED CONVECTION MOVES THROUGH TOMORROW...BUT TO REFLECT THE
DECREASED CHANCES...T WAS REMOVED FROM THE WX GRIDS. QPF WITH THIS
INITIAL BAND OF RAIN WILL GENERALLY RANGE FROM 0.1" TO 0.4"
(HIGHEST IN THE N & E PART OF THE CWA). MUCH MORE SUBSTANTIAL RAIN
WILL MATERIALIZE FROM THE SOUTH BEGINNING WED NIGHT AND THIS WILL
BE DISCUSSED IN MORE DETAIL IN THE LONG TERM DISCUSSION.

WINDS WILL BE ANOTHER CONCERN FOR TOMORROW AS THE GRADIENT REALLY
TIGHTENS UP IN ADVANCE OF THIS SYSTEM. TYPICALLY WINDY
SPOTS...ESPECIALLY ALONG THE BUFFALO RIDGE WILL SEE WINDS INCREASING
OUT OF THE SE TO THE TUNE OF 25-35 MPH WITH GUSTS AS HIGH AS 45
MPH FROM LATE MORNING THROUGH LATE AFTN. UP TO 40KTS OF WIND IS
PROGGED BY THE MODELS AT THE TOP OF THE MIXED LAYER...WHICH WOULD
TRANSLATE INTO GUSTS APPROACHING 45 MPH. THE ONLY POTENTIAL ISSUE
WITH REALIZING WINDS THIS STRONG IS CLOUD COVER...WHICH MAY INHIBIT
MIXING FROM REACHING ITS FULL POTENTIAL. WITH THAT SAID...AFTER
COORDINATION WITH WFOS FSD AND ABR...A WIND ADVISORY HAS BEEN
HOISTED FOR THIS HAZARD.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 346 PM CDT TUE APR 22 2014

LOW LEVEL MOISTURE TRANSPORT WILL INCREASE WEDNESDAY NIGHT AHEAD
OF A LARGE LOW PRESSURE SYSTEM MOVING SLOWLY EAST FROM THE CENTRAL
PLAINS. THE NOSE OF THE MOISTURE TRANSPORT PUSHES INTO SOUTHERN
MINNESOTA DURING THE EVENING AND REACHES WESTERN WISCONSIN BY
DAYBREAK THURSDAY. PW VALUES ACROSS SOUTHERN MN INCREASE TO A
LITTLE MORE THAN AN INCH...WHICH IS 200 PERCENT OF NORMAL.
INSTABILITY IS ALSO INCREASING AS WELL WITH THUNDERSTORMS BECOMING
MORE LIKELY. VARIOUS MODEL SOLUTIONS FOR THE PAST FEW DAYS HAVE
BEEN POINTING AT A PRETTY GOOD CONVECTIVE PRECIPITATION EVENT
UNFOLDING ACROSS WESTERN IA WEDNESDAY EVENING AND SPREADING
NORTHEAST ACROSS SOUTHEAST MINNESOTA TO AROUND EAU CLAIRE BY
THURSDAY MORNING. RAIN AMOUNTS OF 1 TO 1.5 INCHES ARE POSSIBLE IN
THIS CORRIDOR ALTHOUGH THE LAYOUT AGAIN IS SIMILAR TO THIS PAST
SUNDAY NIGHT WHERE THE HEAVIEST RAIN WAS JUST SOUTH OF OUR CWA.
FARTHER NORTH...STRONG ADIABATIC OMEGA IS SEEN MOVING THROUGH ON
THE 295K THETA SURFACE ALONG WITH A BAND OF MID LEVEL
FRONTOGENESIS. RAIN AMOUNTS OF A HALF INCH OR MORE ARE LIKELY.
OVERALL...CATEGORICAL POPS COVER THE FA WEDNESDAY NIGHT.

ON THURSDAY...THE CENTER OF THE SURFACE LOW IS OVER IOWA WITH
AN INVERTED TROUGH EXTENDING TO THE NORTH ACROSS MINNESOTA. THESE
FEATURES WILL BE MOVING SLOWLY EAST WITH ANOTHER HIGH POP
DAY...ESPECIALLY FOR EASTERN MINNESOTA AND WESTERN WISCONSIN.
ANOTHER HALF INCH OF RAIN IS LIKELY. THE THREAT FOR SEVERE WEATHER
ON THURSDAY LOOKS NIL AT THIS TIME ACROSS OUR FA. SO WE WILL HAVE
TO MANUFACTURE OUR OWN FOR THE SEVERE WEATHER DRILLS THURSDAY
AFTERNOON AND EVENING.

DRIER AIR WORKS INTO AT LEAST THE SOUTHERN HALF OF MINNESOTA AND
ADJOINING AREAS OF WISCONSIN THURSDAY NIGHT AND FRIDAY...CUTTING
OFF THE PRECIPITATION. NORTHERN AREAS WILL STILL BE NEAR A
BAROCLINIC ZONE WITH THE THREAT FOR SHOWERS AND ISOLATED
THUNDERSTORMS. BY SATURDAY...IT LOOKS LIKE ALL OF THE AREA WILL BE
DRY. HOWEVER...THIS WILL NOT LAST LONG. A FAST MOVING SHORT WAVE
IS PROJECTED INTO THE FOUR CORNERS REGION BY SATURDAY NIGHT WITH
THIS FEATURE LIFTING INTO THE CENTRAL PLAINS BY SUNDAY. THIS WILL
BRING MORE WAA PRECIPITATION BACK INTO THE UPPER MISSISSIPPI
VALLEY REGION SATURDAY NIGHT AND CONTINUING OFF AND ON FOR SEVERAL
DAYS. THIS IS A LITTLE BIT OF A CHANGE FROM WHAT WE WERE SEEING
THE PAST FEW DAYS. TODAY...THE ECMWF HAS JOINED THE GFS ON
TURNING THE WAVE OVER THE CENTRAL PLAINS INTO A CUT-OFF LOW. A
LOOK AT THE HEMISPHERIC FLOW SHOWS THAT A CUT-OFF HIGH DEVELOPS
OVER SOUTHERN GREENLAND DURING THE WEEKEND WITH A REX BLOCK (HIGH
OVER LOW) DEVELOPING EARLY NEXT WEEK IN THE WESTERN ATLANTIC. WHILE
THIS IS OCCURRING...BOTH THE GFS AND ECMWF DEVELOP A SECOND REX
BLOCK FROM CENTRAL CANADA INTO THE CENTRAL PLAINS. QUITE THE
SYMMETRY IN THE ANIMATION OF THE NORTHERN HEMISPHERIC FLOW.
ANYWAY...THERE/S NO WHERE FOR OUR UPPER LOW TO GO WITH THE BLOCK
DOWNSTREAM. IN FACT OUR LOW IS ONLY FORECAST TO REACH THE EASTERN
GREAT LAKES BY LATE NEXT WEEK. HENCE...BELOW NORMAL TEMPERATURES
WILL OCCUR THROUGH THE LONG TERM PORTION OF THIS FORECAST. THIS
SHOULD SEAL THE MONTH OF APRIL BEING BELOW NORMAL HERE AT MSP.
THIS WOULD BE 6 MONTHS IN A ROW. ONE FINAL THING...WE HAD TO KEEP
THE S WORD IN THE FORECAST SUNDAY NIGHT AND MONDAY NIGHT WITH THE
COLD THERMAL PROFILE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1154 AM CDT TUE APR 22 2014

HIGH PRESSURE CENTERED OVER CENTRAL MN AT THE NOON HOUR TODAY.
THIS HIGH WILL SLOWLY SHIFT OFF TO THE EAST OVERNIGHT AS RETURN
FLOW SETS UP. A LARGE AND COMPLEX FRONTAL SYSTEM WILL APPROACH
FROM THE WEST LATE TONIGHT...SPREADING SHOWERS FROM WEST TO EAST
BEGINNING 12-13Z AT KAXN. THE MOST PREVALENT SHOWER ACTIVITY LOOKS
TO BE NORTH AND EAST OF THE MN RIVER THROUGH EARLY AFTN. THUNDER
IS NOT EXPECTED AS THE MAIN AXIS OF INSTABILITY REMAINS WELL TO
THE SOUTH AND WEST. OUTSIDE OF ANY HEAVIER SHOWER ACTIVITY...VFR
SHOULD PREVAIL FOR MUCH OF THIS TAF PD. SE WINDS WILL RISE
DRAMATICALLY (GUSTS TO 25KT+)...ESPECIALLY OUT WEST BY MID-MORNING AND
CONTINUING THROUGH THE DAY.

KMSP...RIDGE AXIS STILL TO THE WEST OF MSP AS OF NOON...BUT BEFORE
THE FINAL PUSH OF THE EVE...WINDS WILL SWING AROUND TO THE ENE BUT
ALSO DECREASE TO 7KT OR LESS. SE WINDS WILL BE BLOWING FIRST THING IN
THE MORNING WITH A BAND OF VFR SHOWERS MOVING THROUGH 16-22Z.

/OUTLOOK FOR KMSP/
WEDNESDAY NIGHT...MVFR CEILINGS AND VISIBILITIES EXPECTED WITH
RAIN... IFR POSSIBLE. SOUTHEAST WIND 10 TO 20 KT.
THURSDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE EARLY.
SOUTHEAST WIND 5 TO 15 KT SHIFTING NORTHWEST.
THURSDAY NIGHT...VFR. NORTHWEST WIND 5 TO 10 KT.
FRI-SAT...VFR. NORTH WIND 5 TO 15 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY FROM 11 AM TO 6 PM CDT WEDNESDAY FOR MNZ047-
     054>056-064-065-073-074-082-091.

WI...NONE.
&&

$$

SHORT TERM...JCA
LONG TERM...RAH
AVIATION...JCA






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