Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 291717
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1217 PM CDT WED APR 29 2015

.UPDATE...FOR 18Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT WED APR 29 2015

YET ANOTHER DRY HIGH PRESSURE WAS MOVING INTO MN THIS MORNING...WITH
NW FLOW IN PLACE ALOFT TO THE EAST OF AN UPPER RIDE THAT EXTENDS
FROM SOUTHERN CAL UP INTO SASKATCHEWAN. THE NEAREST FEATURE OF
INTEREST ON WATER VAPOR IS A RELATIVELY STRONG SHORT WAVE OVER NW
ONTARIO THAT WILL HEAD SOUTH ALONG THE SPINE OF LAKE MICHIGAN TODAY.
AS IT DOES SO...IT WILL DRAG SOME COOLER H85 TEMPS DOWN THROUGH
WI...WITH VALUES DOWN BETWEEN 0C AND 4C IN WRN WI. USING THE MIX
DOWN PROCEDURE TO H8 WITH A SFC SUPER ADIABATIC CORRECTION ONLY
NETTED HIGHS IN THE UPPER 60S IN WRN MN...WITH LOWER 60S IN WRN
WI...WHICH IS ABOUT 5 DEGS COOLER THAN WHAT THE INHERITED FORECAST
HAD. GIVEN HOW TEMPERATURES HAVE PERFORMED ON DRY...DEEPLY MIXED
DAYS RECENTLY...WAS HESITANT TO KNOCK TOO MUCH OFF THE HIGHS
TODAY...BUT DID NUDGE THEM BACK A COUPLE OF DEGREES PRETTY MUCH AREA
WIDE THANKS TO THOSE COOLER H85 TEMPS.

TONIGHT...THE SFC RIDGE MOVES OVERHEAD AND ONE WOULD THINK THAT
THERE WOULD NOT BE MUCH TO WORRY ABOUT WITH PRECIP...BUT THE HIRES
ARW/NMM ALONG THE WITH LOCAL MPX WRF-ARW SHOW A BATCH OF LIGHT RAIN
MOVING THROUGH WESTERN WI LATE TONIGHT. EVEN THE SREF PROBS FOR
MEASURABLE PRECIP SHOW LOW PROBABILITIES DEVELOPING IN THIS AREA
LATE TONIGHT. THIS LOOKS TO BE IN RESPONSE TO A LITTLE BATCH OF
MOISTURE AND FRONTOGENESIS IN THE H85-H7 LAYER MOVING DOWN THE
WEST SIDE OF THE UPPER WAVE OVER MICHIGAN. RIGHT NOW...THIS IS
ASSOCIATED WITH A BATCH OF CLOUD COVER MOVING ALONG THE
MANITOBA/ONTARIO BORDER. GIVEN HOW DRY THE LOW LEVELS WILL
BE...DID NOT MENTION ANY PRECIP FOR TONIGHT...BUT WILL BE
SOMETHING TO KEEP AN EYE ON. OTHERWISE...MUCH OF MN WILL SEE CLEAR
SKIES AND LIGHT WINDS WITH THE DRY HIGH OVERHEAD WHICH WILL SET UP
ANOTHER IDEAL RADIATIONAL COOLING NIGHT. WENT WITH A 50/50 BLEND
OF THE BIAS CORRECTED CANADIAN/ECMWF FOR LOW TONIGHT...WHICH HAS
LOWS BACK IN THE UPPER 30S/LOWER 40S FOR MOST OF THE AREA TONIGHT.
THE OTHER ADVANTAGE TO THIS BLEND IS IT HAD SLIGHTLY HIGHER LOWS
ALONG THE MN/WI BORDER... WHERE CLOUD COVER FROM THE FEATURE
MENTIONED ABOVE SHOULD BE.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 415 AM CDT WED APR 29 2015

THE FIRST WEEK OF MAY LOOKS QUITE SUMMERLIKE...ESPECIALLY THIS
WEEKEND. FOR THE LAST DAY OF APRIL...THURSDAY...A DECENT THERMAL
GRADIENT FROM WEST TO EAST WILL MARK THE BEGINNING OF SAID STOUT
WARMING TREND. 850 MB TEMPS WILL REACH AROUND +10C ACROSS WESTERN
MN BUT AROUND +5C OVER WESTERN WI. MIXING WILL EXTEND TO AT LEAST
850 MB FACILITATING HIGHS IN THE LOW/MID 70S WEST AND MID 60S
EAST. HOWEVER...WINDS WILL BE LIGHT...THE AIR AND SOIL ARE
DRY...AND THE SUN ANGLE IS NOW PRETTY STRONG...SO SHOULD SEE
SUPERADIABATIC EFFECTS NEAR THE SURFACE. TOOK A MIXED PROFILE TO
850 MB AND ADDED A FEW MORE DEGREES...WHICH IS WARMER THAN
GUIDANCE CONSENSUS.

A WEAKENING WAVE WILL PUSH ACROSS THE NORTHERN PLAINS/UPPER
MIDWEST THURSDAY NIGHT AND DISSIPATE FRIDAY. A BAND OF SHOWERS
SHOULD ACCOMPANY THIS FEATURE THROUGH THURSDAY NIGHT...BUT WILL
BE IN A WANING PHASE BY FRIDAY MORNING ACROSS THE EASTERN CWA.
MAINTAINED MEDIUM RANGE POPS CENTRAL AND WEST WITH LOW CHANCE
ACROSS WI. CLOUDS WILL CLEAR BY AFTERNOON AND NEUTRAL TEMP
ADVECTION WILL BRING ANOTHER PLEASANT DAY WITH HIGHS IN THE UPPER
60S TO MID 70S.

FASTER ZONAL FLOW WILL DEVELOP ALONG THE CANADIAN BORDER THIS
WEEKEND AS A LOW PRESSURE CENTER PASSES TO THE NORTH. THIS WILL
FOCUS THE THERMAL RIDGING FROM THE CENTRAL PLAINS INTO THE WESTERN
GREAT LAKES AND UPPER MISSISSIPPI VALLEY. SATURDAY AND SUNDAY
COULD BE RATHER WARM. DRY BOUNDARY LAYER AIR WITH MIN RH VALUES OF
20 TO 30 PERCENT SATURDAY AFTERNOON WILL ENHANCE THE WARMING
POTENTIAL IF WINDS CAN REMAIN ABOUT 5 KT OR LESS. BY SUNDAY...THE
THERMAL RIDGE WILL PASS OVERHEAD IN ADVANCE OF A SEWD SAGGING COLD
FRONT. IF THE FRONT MAINTAINS CURRENT TIMING OR SLOWS...SRN MN
COULD SOAR INTO THE MID 80S OR WARMER AS +13 TO +15C AIR AT 850
BUILDS IN. OF COURSE IT WOULD BE QUITE A BIT COOLER IF THE FRONT
SPEEDS UP SLIGHTLY. DEEPER GULF MOISTURE ARRIVES LATE SUNDAY
MARKED BY PW VALUES ABOVE 1 INCH AND WITHOUT THE PRESENCE OF MUCH
CAPPING...SHOULD SEE SHOWER AND THUNDERSTORM DEVELOPMENT BY
EVENING ALONG THE FRONT. SHEAR APPEARS TOO WEAK ATTM TO SUSTAIN
ANY MEANINGFUL CONVECTION.

BROAD TROUGHING ACROSS THE WEST WILL BRING LOW PRESSURE OVER THE
CENTRAL PLAINS EARLY NEXT WEEK. THE FRONT FROM SUNDAY WILL STALL
SOMEWHERE ACROSS THE MIDDLE MISSISSIPPI VALLEY WITH CONTINUED
FOCUS FOR SHOWERS AND THUNDERSTORM DEVELOPMENT. THERE ARE
INDICATIONS THIS FRONT COULD LIFT BACK NORTH TOWARD MIDWEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1217 PM CDT WED APR 29 2015

HIGH PRESSURE WILL FACILITATE VFR CONDITIONS THROUGH THE PERIOD. A
BATCH OF CLOUDS CIRCA 9KFT FILTER ACROSS EASTERN MN AND WEST
CENTRAL WI THIS AFTERNOON AND EVENING...OTHERWISE MOSTLY CLEAR
SKIES WILL PREVAIL. NORTH-NORTHEAST WINDS AT 5-10 KTS WITH HIGHER
GUSTS /INTO THE MID TEENS/ THIS AFTERNOON...BECOMING LIGHT AND
VARIABLE FOR TONIGHT.

KMSP...
NO NOTABLE DEVIATIONS FROM CURRENT TAF ARE EXPECTED.

/OUTLOOK FOR KMSP/
THU NIGHT...VFR. WINDS ESE 5-7 KTS.
FRI...VFR. CHANCE -SHRA. WINDS SW 5-10 KTS.
SAT...VFR. WINDS SW 7-10 KTS.
SUN...-SHRA WITH MVFR POSSIBLE. WINDS S 5-10 KTS.

&&

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

$$


SHORT TERM...MPG
LONG TERM...BORGHOFF
AVIATION...LS



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