Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 092340
AFDMPX

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

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM CDT WED JUL 9 2014

THE FORECAST AREA REMAINS NEAR THE INFLECTION POINT OF ANTICYCLONIC
FLOW IN THE WESTERN CONUS AND CYCLONIC FLOW OVER THE GREAT LAKES AND
EASTERN CONUS. A WEAK SURFACE RIDGE IS PARKED OVERHEAD...SO THE
WINDS ARE MUCH LIGHTER THAN YESTERDAY. COOLER TEMPS ALOFT AND
SURFACE HEATING HAS COMBINED TO DEVELOP A SCATTERED TO BROKEN CU
FIELD ACROSS THE FORECAST AREA. THE ONGOING THUNDERSTORMS IN
NEBRASKA ARE ASSOCIATED WITH AN AREA 850-700MB FGEN AND ALONG AN
AXIS OF HIGHER LOW LEVEL MOISTURE AND WILL REMAIN WELL SW TONIGHT.
EVENTUALLY THE FLOW WILL SLOWLY TURN MORE TO THE SOUTHEAST OVER
THE NEXT 18-24 HOURS LOCALLY AND THE LLJ SHOULD BEGIN ADVECTING
SOME OF THIS MOISTURE TO OUR SW CLOSER TO THE FORECAST AREA. BY
TOMORROW AFTERNOON...WE EXPECT AT LEAST A MID DECK WITH THE
POTENTIAL FOR A FEW LIGHT SHOWERS TO BE APPROACHING THE WESTERN
MN/SD BORDER. MEANWHILE...THE SURFACE BOUNDARY ASSOCIATED WITH A
DEVELOPING CYCLONE IN CANADA HANGS WELL TO OUR WEST TOMORROW. NO
BIG CHANGES TO THE FORECAST...BESIDES A SLIGHT SLOWING OF THE POPS
BEFORE 00Z TOMORROW IN WESTERN MN. WE WERE A LITTLE COOLER THAN
EXPECTED TODAY...WHICH MAKES US A LITTLE LESS CONFIDENT IN HITTING
80 DEGREES TOMORROW...BUT AT LEAST WE`LL GET A SOUTHERLY COMPONENT
TO THE BOUNDARY LAYER WINDS DURING THE AFTERNOON AND 925-850MB
TEMPS WARM 2-4 C DURING THE DAY TOMORROW.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 412 PM CDT WED JUL 9 2014

OBVIOUSLY THE BIG STORY FOR THE LONG TERM IS THE SIGNIFICANT COOL
DOWN COMING EARLY NEXT WEEK AS THE WEATHER PATTERN TAKES ON THE LOOK
OF THE TYPE OF PATTERNS WE WERE DEALING WITH 6 MONTHS AGO. BEFORE
THEN THOUGH...THERE WILL BE A PROLONGED PERIOD OF RAIN CHANCES
STARTING THURSDAY NIGHT AND LASTING THROUGH MONDAY. THE HIGHEST
CONFIDENCE IN THE PRECIP FORECAST COMES THURSDAY NIGHT INTO FRIDAY
MORNING...WITH QUITE A BIT OF UNCERTAINTY FOR PRECIP CHANCES FRIDAY
AFTERNOON THROUGH MONDAY...THOUGH ON THE WHOLE THIS PERIOD LOOKS TO
BE MAINLY DRY.

NORTH AMERICAN WATER VAPOR IMAGERY THIS AFTERNOON SHOWS TWO FEATURES
OF INTEREST OFF TO OUR WEST. A SHORT WAVE APPROACHING IDAHO...AND A
DEEP CLOSED LOW SPINNING ACROSS NRN BRITISH COLUMBIA. THAT SRN
SHORTWAVE WILL BE TRACKING ACROSS MN/WI THU NIGHT INTO FRIDAY
MORNING...WHILE THE BC LOW WILL BOMB OUT OVER WRN ONTARIO
SUNDAY...RESULTING IN THE SEASONABLY COLD WEATHER EXPECTED FOR THE
FIRST HALF OF NEXT WEEK.

THURSDAY NIGHT INTO FRIDAY MORNING WILL REPRESENT THE BEST CHANCE
FOR PRECIP AREA WIDE DURING THE LONG TERM AS THE WAVE CURRENTLY NEAR
IDAHO MOVES THROUGH AND A COLD FRONT WORKS INTO MN. WHEN LOOKING AT
H85 AND SFC CHARTS IN CONJUNCTION WITH H5 FORECASTS...IT BECOMES
OBVIOUS THAT THE TRUE DRIVER OF THE LOW LEVEL FEATURES WILL BE THE
CLOSED LOW UP IN CANADA AS OPPOSED TO THE LEAD SHORTWAVE COMING OUT
OF THE NRN ROCKIES. THE SFC/H85 FRONTS WILL BE LAGGING THIS LEAD
SHORTWAVE BY QUITE A DISTANCE. THIS LIKELY MEANS THAT THE FIRST HALF
OF THURSDAY NIGHT WILL BE SPENT WITH LOTS OF VIRGA/SPRINKLES AS THE
SRN WAVE WORKS THROUGH...WITH BETTER PRECIP CHANCES COMING AFTER
MIDNIGHT AS THE SFC AND H85 TROUGH COME OUT OF THE DAKOTAS AND INTO
WRN MN. WITH THE 12Z MODELS...BEGINNING TO SEE A TREND TOWARD A
SPLIT PRECIP REGIME SHOWING UP...WITH THE BEST PRECIP SIGNALS
REMAINING UP IN CANADA CLOSER TO THE BETTER UPPER FORCING AND DOWN
ACROSS IA INTO SRN MN WHERE THE LLJ WILL BE COMING UP INTO...THIS
MAY LEAVE MUCH OF THE MPX CWA WITH LITTLE IN THE WAY FORCING/DEEP
MOISTURE TO WORK WITH.

FOR FRIDAY THROUGH SUNDAY...THE QUESTION BECOMES WHERE ARE THE
FRONTAL/OUTFLOW BOUNDARIES EACH DAY. WE WILL BE ON THE SOUTH END OF
THE FRONT THURSDAY NIGHT AND IT WILL WASHOUT AND BECOME RATHER
ILL-DEFINED GOING INTO THE WEEKEND. ALTHOUGH A WIND SHIFT BOUNDARY
MAY WORK THROUGH THE AREA...ALL GUIDANCE SHOWS DEWPS UP IN THE 60S
UNTIL THE MAIN POLAR COLD FRONT COMES THROUGH SUNDAY NIGHT. FOR THE
MOST PART...MODELS ARE DRY FRIDAY THROUGH THE WEEKEND...SO CUT BACK
POPS CONSIDERABLY...HOLDING MOST AREAS/TIMES TO SLIGHTS THROUGH THE
WEEKEND. THE ONLY EXCEPTION WAS SATURDAY AFTERNOON DOWN ALONG
I-90...WHERE THE GEM AND ECMWF SHOW THE FRONT LIFTING BACK NORTH
ACROSS IOWA DURING THE AFTERNOON AS A WEAK SFC LOW TRACK ALONG/NEAR
I-80. BOTH OF THESE MODELS ARE SHOWING THE POTENTIAL FOR AN MCS TYPE
SYSTEM WORKING ACROSS THE IA BORDER.

FOR SEVERE CHANCES THROUGH THE WEEKEND...THE DAY THAT LOOKS TO HAVE
TO MOST POTENTIAL IS FRIDAY...AS INSTABILITY BUILDS ALONG THE
MOISTURE GRADIENT THAT COMES IN THURSDAY NIGHT. BULK SHEAR ON THE
ECMWF IS AROUND 40 KTS...BUT THERE IS VIRTUALLY NO SFC FLOW TO SPEAK
OF...SO WITH LIMITED SFC FORCING...YOU ARE SEEING LIMITED QPF
GENERATION...BUT IF ANYTHING DID DEVELOP...GIVEN THE MODEST AND
INSTABILITY WITH THE DEEP SHEAR...IT WOULD HAVE THE POTENTIAL BECOME
ORGANIZED AND POTENTIALLY SEVERE. BY SATURDAY AND SUNDAY...THE
STRONG INSTABILITY LOOKS TO REMAIN OFF TO OUR SOUTH...WHICH WILL
LIMIT ANY SEVERE POTENTIAL.

AS ALLUDED TO EARLIER...THE ARRIVAL OF A POLAR FRONT SUNDAY NIGHT
WILL FINALLY PUSH THE SFC MOISTURE OUT OF THE AREA. THIS FRONT IS IN
RESPONSE TO THE H5 LOW DEEPENING TO AROUND 550 DM OVER WRN ONTARIO
ON SUNDAY...WHICH WILL FORCE A 1025 MB SFC HIGH SOUTH OUT OF THE
CANADIAN PRAIRIES. BY TUESDAY...BOTH THE GFS/ECMWF SHOW H85 TEMPS
DROPPING DOWN TO AROUND 5C...OR A LITTLE BETTER THAN 2 STANDARD
DEVIATIONS BLOW NORMAL. THIS WILL RESULT IN HIGHS BY TUESDAY RUNNING
ABOUT 15 DEGREES BELOW NORMAL...WITH TEMPERATURES STRUGGLING TO HIT
70 DESPITE NEARLY FULL JULY SUNSHINE. WITH DEWPS FALLING BACK INTO
THE 40S...WE WILL ALSO SEE SOME COOL MORNINGS...ESPECIALLY TUESDAY
AND WEDNESDAY MORNINGS...WHEN WE WILL LIKELY SEE A FEW OF OUR
TRADITIONAL COLD SPOTS DIPPING DOWN INTO THE 40S. NOT EXPECTING ANY
RECORD LOWS TO FALL AT THIS POINT THOUGH. WOULD NEED TO SEE LOWS GET
DOWN BELOW 45 TO START THINKING ABOUT RECORDS AT EAU/STC AND 50 AT
MSP. AT THE MOMENT...WE HAVE LOWS THAT ARE ABOUT 5 DEGS CLEAR OF
RECORDS TUE/WED MORNINGS.

ONLY CHANCE FOR PRECIP NEXT WEEK LOOKS TO COME MONDAY AS VERY COLD
TEMPERATURES COME DOWN ALOFT. THE ECMWF IN PARTICULAR SHOWS PRETTY
GOOD INSTABILITY SHOWER POTENTIAL DURING THE AFTERNOON NORTH OF
I-94. WITH BEST LIS GREATER THAN 0 AND NO CAPE TO SPEAK OF...REMOVED
ANY THUNDER MENTION FROM THE FORECAST FROM SUNDAY NIGHT ON. FOR THE
REST OF THE WEEK...DRY HIGH PRESSURE TAKES CONTROL...WITH ONLY
MEANINGFUL CHANGE IN THE WEATHER BEING A GRADUAL WARMUP AFTER
TUESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 640 PM CDT WED JUL 9 2014

HIGH PRESSURE CENTERED OVER CENTRAL MN THIS EVENING WILL PROVIDE
LIGHT AND VARIABLE WINDS TONIGHT ALONG WITH VFR CONDITIONS. FEW-
SCT CU DEVELOPING ONCE AGAIN ON THURSDAY ALONG WITH INCREASING MID
LEVEL CLOUDS (080-120) AS A WARM FRONT APPROACHES FROM THE CENTRAL
PLAINS. HELD OFF ON ANY SHOWER CHANCES AS THE THREAT REALLY DOES
NOT DEVELOP AT KAXN AND KRWF UNTIL THE END OF THE TAF. CERTAINLY
SHRA/TSRA WILL BE ON THE INCREASE FOR THESE TWO SITES IN THE
11/00Z-06Z TIME FRAME. WINDS BECOMING SSE 8-12 KNOTS BY LATE
THURSDAY MORNING AND CONTINUING THROUGH THE AFTERNOON.

KMSP...FEW CONCERNS THROUGH THE PERIOD WITH VFR PREVAILING. LIGHT
NW WINDS THIS EVENING WILL TURN SE OVERNIGHT AND INCREASE TO NEAR
10 KNOTS FOR THE AFTERNOON AND EVENING. SHRA/TSRA CHANCES ON THE
RISE FROM 11/06-12Z WITH SCT STORMS AROUND THE TWIN CITIES FRIDAY
MORNING.

/OUTLOOK FOR KMSP/

FRI...VFR WITH MVFR/SHRA/TSRA POSSIBLE. WINDS S 10 KTS.
SAT...VFR. WINDS NW 4-8 KTS.
SUN...VFR WITH MVFR/SHRA/TSRA POSSIBLE. WINDS W 6-10 KTS.

&&

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

$$

SHORT TERM...CLF
LONG TERM...MPG
AVIATION...RAH





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