Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 111854
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
154 PM CDT FRI APR 11 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT FRI APR 11 2014

SCATTERED SHOWERS MOVING ACROSS THE FA THIS MORNING CONTINUE TO BE
HINDERED BY PRESENCE OF LOW LEVEL DRY AIR. SOME RAIN IS MAKING
IT TO THE SURFACE...BUT MUCH OF THE REFLECTIVITY ON RADAR THIS
MORNING IS VIRGA...WITH JUST A FEW SITES REPORTING VERY LIGHT
RAIN. THE VIRGA/SCATTERED SHOWERS WILL QUICKLY MOVE EAST THROUGH
THE MORNING AND GIVE WAY TO CLEARING SKIES TODAY. TEMPERATURES
WILL EXCEED YESTERDAYS HIGHS BY A FEW DEGREES GIVEN THE VERY
GRADUAL WARMING TREND EVIDENT AT 850H ON THE RAP THROUGH THIS
EVENING.

FOR TONIGHT...AN UPPER LEVEL SHORTWAVE TROUGH WILL PUSH ACROSS
CENTRAL MINNESOTA INTO WISCONSIN. BOTH FORCING AND AVAILABLE
MOISTURE LEND HIGHER CONFIDENCE TO PRECIPITATION FORMING AND
EXPANDING DURING THE OVERNIGHT HOURS.  A 100+ KT JET STREAK TO THE
NE OF THE FA PLACES US SOLIDLY IN THE RIGHT-ENTRANCE REGION
INDICATING STRONG UPPER LEVEL DIVERGENCE. IN THE LOW LEVELS...A
LOW LEVEL JET WILL GATHER STRENGTH OVERNIGHT AND WILL POKE INTO
SOUTHERN MINNESOTA. NOT ONLY WILL THIS JET SUPPLY THIS AREA WITH
INCREASING MOISTURE...STRONG WARM AIR ADVECTION WILL ALSO BE
OCCURRING PROVIDING STRONG LOW LEVEL LIFT TO THIS REGION. THE LOW
LEVEL CONVERGENCE AT THE NOSE OF THE JET COUPLED WITH THE UPPER
LEVEL DIVERGENCE FROM THE UPPER LEVEL JET INDICATES STRONG
DIFFERENTIAL DIVERGENCE ONGOING OVERNIGHT ACROSS EAST CENTRAL
MINNESOTA INTO FAR WESTERN WISCONSIN. LIKELY TO CATEGORICAL POPS
HAVE BEEN ADDED TO THESE AREAS AFTER 09Z WHEN THE LOW LEVEL JET
STRENGTHENS. THE NAM INDICATED A MUCH DRIER SOLUTION...PREFERRED A
BLEND OF THE GFS/ECMWF GIVEN THE STRONG FORCING AND MOISTURE
TRANSPORT OCCURRING WITH THE STRENGTHENING LOW LEVEL JET
OVERNIGHT. LOW LEVEL DRY AIR SHOULD BE QUICKLY OVERCOME IN THIS
CASE. NEGATIVE LIFTED INDEX VALUES AND WEAK MOST UNSTABLE CAPE DO
PUSH INTO FAR SOUTHERN MINNESOTA AFTER 09Z...SO THUNDERSTORMS WILL
BE A POSSIBILITY EARLY TOMORROW MORNING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 400 AM CDT FRI APR 11 2014

MAIN POINTS:

1) PRECIP EVENT IS STILL ON TRACK FOR SATURDAY WITH MOST
OF THE RAIN EXPECTED IN THE MORNING.

2) THERE ARE NOTABLE MODEL DIFFERENCES ON THE LOCATION OF THE QPF
AXIS ON SUNDAY.

3) THE GFS HAS TRENDED TOWARD THE ECMWF AND IS NOW GOING COLDER
WITH TEMPERATURES MON-WED.

NOW THAT WE`RE 24-36 HOURS OUT FROM THE RAIN EVENT ON
SATURDAY...IT`S NO SURPRISE THERE IS BETTER MODEL AGREEMENT ON THE
PLACEMENT OF RAIN AND EXPECTED AMOUNTS. THE GFS AND ECMWF ARE IN
BETTER AGREEMENT WHEN COMPARED TO THE NAM...WHICH IS FARTHER NORTH
WITH THE MOISTURE ADVECTION AND PLACEMENT OF THE 800-600MB FGEN.
THE NAM THEREFORE HAS MORE WARMTH FARTHER NORTH AND THE PRECIP
PLACEMENT ACROSS NORTHERN MN...WHERE THE GFS AND ECMWF DEVELOP
MORE RAIN OVER CENTRAL AND PORTIONS OF SOUTHERN MN. TRENDS IN THE
ISENTROPIC LIFT AND SATURATION SUGGEST WESTERN MN...ESPECIALLY SW
MN COULD MISS OUT ON A LOT OF THE PRECIP WITH DEVELOPMENT MORE
LIKELY THE FARTHER EAST YOU GO IN MN. FOR THE EASTERN HALF OF THE
FORECAST AREA...IT LOOKS LIKE A GOOD 0.10"-0.40" EVENT WITH THE
HIGHER TOTALS OCCURRING WHERE THERE IS EMBEDDED CONVECTION. THAT
IS LIKELY GIVEN THE TONGUE OF 500-1000 J/KG OF MUCAPE AND BEST LI
NEAR 0. WE TRIED TO REMAIN STEADFAST IN KEEPING THE CONVECTION
CONFINED TO THE WARM SECTOR OR NEAR THE SURFACE WARM FRONT DURING
THE DAY ON SATURDAY. BY SATURDAY EVENING THE SURFACE LOW/TROUGH
SHOULD HAVE MADE ENOUGH PROGRESS TO THE EAST THAT THE CONVECTION
SHOULD BE SOUTH AND EAST OF THE FORECAST AREA. THEREFORE...AFTER
THE RAIN CLEARS SATURDAY MORNING...WE ARE MUCH MORE CONFIDENT IN A
MAINLY DRY AFTERNOON THAN WE WERE A DAY OR TWO AGO.

THE AMOUNT OF PRECIP AND SNOW CHANCES ON SUNDAY ALL DEPEND ON
WHERE THE BAROCLINIC ZONE SETS UP. AS OF RIGHT NOW...MODEL
CONSENSUS KEEPS THE BEST FORCING ACROSS IA...FAR SOUTHEAST MN AND
WI. THIS WILL BE MODERATE RAIN EVENT WITH AN INCH OR TWO OF QPF
BEING FORECAST. AT THIS POINT...SOUTHERN MN AND WEST CENTRAL WI
MISS OUT ON MUCH OF THE RAIN. THE 11.00/06 NAM SEEMS TOO FAR TO
THE NORTH AND THE TRACK RECORD THIS WINTER HASN`T BEEN GREAT FOR
THE NAM OUTSIDE OF IT`S 0-24HR FORECAST. WE SIDED WITH MORE OF A
ECMWF/GEM/GFS BLEND AND UNLESS WE SEE THESE THREE MODELING SYSTEMS
TREND ANOTHER 100-150 MILES NORTH...SUNDAY LOOKS DRY /CLOUDY/
FOR MUCH OF THE FORECAST AREA. THIS SEEMS LIKELY GIVEN THE RUN-TO-
RUN CONSISTENCY OVER THE PAST 3-4 CYCLES.

SUNDAY-WEDNESDAY STILL LOOKS COLD AND AS MENTIONED ABOVE. THE
THERMAL PROFILE OFF THE GFS NOW MATCHES THE PREVIOUS ECMWF RUNS
THAT SHOW A SLOWER/DEEPER TROUGH AND A NICE 850MB COLD POCKET.
SO...JUST AS WE GET APRIL`S MONTHLY TEMPERATURE BACK UP NEAR
NORMAL...WE SHOULD DROP IT BACK DOWN WITH 20S FOR LOWS AND 40S FOR
HIGHS. BELIEVE IT OR NOT...ANOTHER NEAR ZERO NIGHT CAN NOT BE
RULED OUT IN SOME OF THE COLD SPOTS IN NORTHERN MN TUESDAY
MORNING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 127 PM CDT FRI APR 11 2014

WINDS HAVE BEEN VERY TRICKY THRU THE MIDDLE PORTION OF THE DAY
TDA. HAVE SEEN WINDS ALL OVER THE COMPASS WITH SPEEDS 5-10 KT THRU
NOON...DUE TO A WEAK SFC BOUNDARY DRAPED AND WOBBLING ACRS
CENTRAL PORTIONS OF MN. WITH THIS BOUNDARY DISSIPATING AND
SHIFTING OFF TO THE E...WINDS ARE FINALLY GOING TO NW WHICH IS
CONSISTENT WITH BEING ON THE BACKSIDE OF THE LOW. THIS HAS ALSO
ALLOWED SKIES TO CLEAR OUT THIS AFTN AHEAD OF THE NEXT INCOMING
SYSTEM. HIGH CLOUDS WILL INCRS FROM THE W OVERNIGHT AND STEADILY
LOWER. INTERMITTENT SHWRS LOOK TO MOVE INTO THE AREA CLOSE TO
MIDNIGHT AND SHORTLY THEREAFTER...NOTHING THAT WOULD REDUCE FLIGHT
CONDS. STEADIER -RA WILL DEVELOP FROM W TO E ACRS THE COVERAGE
AREA DURG THE PRE-DAWN HRS...WITH SOME HEAVIER RAIN ARND DAYBREAK
AND THESE SHWRS MAY DROP CONDS INTO MVFR. AFTER DAYBREAK...PRECIP
INTENSITY WILL GENERALLY LESSEN...AND EVEN END ALTOGETHER...FOR
THE MN SITES WHILE THE WI SITES WILL LIKELY SEE -RA THRU MIDDAY
SAT. IN THE MORE PERSISTENT SHWRS IS WHERE CIGS INTO MVFR RANGE
CAN BE EXPECTED.

KMSP...WINDS HAVE FINALLY SWITCHED TO NW SHORTLY AFTER
INITIALIZATION TIME SO HAVE OPTED TO DO A QUICK AMD AFTER ISSUING
THE ROUTINE TAF TO INDICATE PREVAILING NW WINDS. AM ALSO SEEING
THE MIDLVL AFTN CU CLOUDS POP ON VISIBLE SATELLITE IMAGERY AND
THESE WILL REMAIN IN PLACE THRU SUNSET. GOING INTO THIS EVE...
HIGH STRATUS WILL FILTER IN AND STEADILY LOWER WHILE INCRG IN
COVERAGE TNGT INTO SAT MRNG. SOME INTERMITTENT LIGHT -SHRA MAY
MOVE INTO THE AREA ARND MIDNIGHT...BUT THE MORE STEADIER RAIN WILL
DEVELOP DURG THE PRE-DAWN HRS. NOT EXPECTING PROLONGED DEGRADED
FLIGHT CONDS BUT SOME OCNL MVFR PERIODS CAN BE EXPECTED GOING TWD
DAYBREAK. AFTER THE PRECIP ENDS...MIDLVL CIGS WILL REMAIN. WINDS
WILL BECOME LGT/VRBL THIS EVE THEN SWAP TO SE AHEAD OF THE NEXT
AREA OF LOW PRES. SE TO S WINDS WILL CONTINUE THRU LATE SAT MRNG
THEN WINDS WILL SHIFT TO SW AND W LATE TMRW AFTN AS LOW PRES MOVES
ACRS.

/OUTLOOK FOR KMSP/
SUN...MAINLY VFR. CHC MVFR CIGS/SHRA. WINDS N 10-15 KT.
MON...VFR. WINDS NW 10-15 KT.
TUE...VFR. WINDS NW 10 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...FLOOD WATCH THROUGH TUESDAY MORNING FOR WIZ025-026-028.

&&

$$

SHORT TERM...SPD
LONG TERM...CLF
AVIATION...JPC






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