Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 300830
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
330 AM CDT SUN AUG 30 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN AUG 30 2015

A FEW AREAS OF FOG AND LOW STRATUS HAD DEVELOPED ACROSS THE REGION
ONCE AGAIN THIS MORNING...WITH SOME SITES REPORTING VISIBILITY LESS
THAN A MILE. THIS LOW LEVEL MOISTURE WILL QUICKLY MIX OUT AS
SOUTHERLY WINDS INCREASE THIS MORNING. WARM AIR ADVECTION WILL
OVERSPREAD THE REGION THIS AFTERNOON WHICH SHOULD ALLOW TEMPERATURE
TO WARM INTO THE 80S AT MOST LOCATIONS IN MINNESOTA...AND UPPER 70S
IN WISCONSIN. THE GFS/NAM/RAP GUIDANCE SHOWS POTENTIAL FOR 90 DEGREE
READINGS THIS AFTERNOON IN WESTERN MN...AND WOULD BUY THAT IF THE
BOUNDARY LAYER WINDS WERE CLOSER TO 220DEG AS OPPOSED TO
190DEG...BUT MORE IMPORTANTLY THE SMOKE SHOULD FILTER OUT THE
INTENSE SUNSHINE AND TRY TO KEEP TODAYS HIGHS IN CHECK.

CONTINUED WITH A DRY FORECAST...AND INCLUDED PATCHY FOG ALONG I-90
AND IN WEST CENTRAL WISCONSIN. HOWEVER NOT ANTICIPATING MUCH DENSE
FOG SINCE DEWPOINT DEPRESSIONS WILL BE A TAD LARGER...AND THE
SYNOPTIC PRESSURE GRADIENT WILL BE STRONGER WHICH SHOULD KEEP UP THE
SURFACE WINDS. OVERNIGHT LOWS WILL FALL INTO THE MID 60S ACROSS THE
AREA.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT SUN AUG 30 2015

THE LARGE SCALE PATTERN WON/T CHANGE MUCH THROUGH THE PERIOD...
WITH SOUTHWEST UPPER FLOW PREVAILING AS THE WESTERN TROUGH AND
EASTERN RIDGE DON/T APPEAR TO MOVE MUCH UNTIL THE VERY END OF THE
FORECAST PERIOD. AS A RESULT... WE/LL SEE MAINLY WARM AND DRY
WEATHER. THERE WILL BE A FEW CHANCES FOR SOME PCPN AS SHORTWAVES
EJECT FROM THE WESTERN TROUGH AND SHEAR OUT AS THE TRY TO WORK
INTO THE UPPER RIDGE. EVENTUALLY... OVER THE WEEKEND... IT LOOKS
LIKE WE SHOULD GET ENOUGH EASTWARD SHIFT OF THE MAIN UPPER TROUGH
TO PUSH THE SURFACE LOW AND ASSOCIATED FRONTAL BOUNDARY INTO THE
AREA FOR MORE WIDESPREAD CHANCES OF PCPN. THE GUIDANCE IS IN
GENERAL AGREEMENT ON THE OVERALL LARGE SCALE PATTERN... ALTHOUGH
THERE ARE SOME DIFFERENCES IN HOW QUICKLY THE RIDGE BREAKS
DOWN/SHIFTS EAST... WHICH AFFECTS HOW QUICKLY WE SEE THE BETTER
CHANCES OF PCPN MOVE INTO THE AREA. THE ECMWF APPEARS TO BE
SLOWEST IN DOING SO... WHILE THE GFS... FIM... AND GEM ARE MORE
PROGRESSIVE. PATTERN RECOGNITION FOR THIS TIME OF YEAR WOULD
SUGGEST A SLOWER EVOLUTION MAY BE THE MORE LIKELY OUTCOME... BUT
THERE IS A FAIR AMOUNT OF SPREAD IN THE ECMWF ENSEMBLE MEMBERS...
SO TOUGH TO BE TOO CONFIDENT IN GOING WITH ONE PARTICULAR
SOLUTION. AS A RESULT... WILL GO WITH A CONSENSUS APPROACH... WITH
PERHAPS SLIGHTLY MORE WEIGHT ON THE ECMWF.

A WEAK SHORTWAVE WILL MOVE BY MAINLY TO OUR NORTHWEST MONDAY INTO
MONDAY NIGHT... WITH ANY PCPN PRIMARILY OCCURRING TO OUR NORTH.
INCLUDED SOME LOW CHANCE POPS OVER THE FAR NORTHWEST AND NORTH
MONDAY NIGHT ALONG THE REMNANTS OF THE WASHED OUT FRONT ASSOCIATED
WITH THAT UPPER WAVE. LINGERED SOME LOW CHANCE POPS OVER THE FAR
NORTH ON TUESDAY IN THE VICINITY OF THE BAROCLINIC ZONE... BUT
ANYTHING THAT OCCURS WOULD BE ISOLATED. THERE IS A CHANCE FOR SOME
SHRA/TSRA OVER THE SOUTH AND EAST TUESDAY NIGHT AND WEDNESDAY IN
ASSOCIATION WITH SOME ENHANCED WARM ADVECTION AND ELEVATED
INSTABILITY ADVERTISED BY THE MEDIUM RANGE GUIDANCE... BUT ONCE
AGAIN WOULD NOT EXPECT ANYTHING TO WIDE SPREAD GIVEN THE LACK OF
SIGNIFICANT/PERSISTENT LARGE SCALE FORCING. SIMILAR CONDITIONS
PERSIST ACROSS MUCH OF THE AREA WEDNESDAY NIGHT INTO THURSDAY...
SO WILL NEED TO CONTINUE SOME CHANCE POPS. HOWEVER... AT THIS
POINT WEDNESDAY NIGHT WOULD APPEAR TO BE THE BETTER TIME FRAME FOR
SHRA/TSRA GIVEN THE NOCTURNAL ENHANCEMENT OF THE LOW LEVEL JET.
WITH THE EXCEPTION OF HIGHLY ISOLATED ACTIVITY THURSDAY NIGHT AND
FRIDAY SHOULD BE DRY AS HEIGHTS RISE AND THE BETTER LOW-MID LEVEL
WARM ADVECTION LOOK TO REFOCUS BACK TO THE WEST AGAIN. HOWEVER...
AS WE HEAD INTO SATURDAY WE SHOULD SEE INCREASING CHANCES START TO
SHIFT EASTWARD INTO THE AREA FROM THE PLAINS AS THE MAIN WESTERN
TROUGH STARTS TO PUSH EAST INTO THE NORTHERN PLAINS. HOWEVER...
THIS IS ALSO WHEN SIGNIFICANT TIMING DIFFERENCES EXIST IN THE
GUIDANCE... SO IT/S STILL A BIT EARLY TO PIN DOWN WHEN/WHERE THE
BEST CHANCES FOR SHRA/TSRA WILL BE OVER THE WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1206 AM CDT SUN AUG 30 2015

FOG IS DEVELOPING OVER PARTS OF SOUTHERN MN/WESTERN WI AND LIFR
STRATUS IS LIFTING NORTH INTO FAR SOUTHERN MN AT TAF ISSUANCE
TIME. THERE IS ALSO A PATCH OF IFR CIGS WEST OF STC AND EAST OF
AXN. EXPECT STRATUS AND FOG TO FILL IN DURING THE NEXT COUPLE
HOURS WITH IFR OR LIFR CONDITIONS EXPECTED AT MOST OF THE TAF
SITES FROM THAT POINT THROUGH MID MORNING SUNDAY. AXN MAY BE THE
EXCEPTION...MOST OF THE HI-RES GUIDANCE KEEPS THE BRUNT OF THIS
DEVELOPMENT JUST EAST BUT DID INCLUDE A TEMPO. CONDITIONS SHOULD
BECOME VFR BY LATE MORNING AS MIXING AND DRIER AIR EATS AWAY AT
THE STRATUS.

KMSP...WILL LIKELY BE A REPEAT OF FRIDAY NIGHT WITH LIFR
CONDITIONS DEVELOPING OVERNIGHT. HI-RES GUIDANCE HAS BEEN VERY
PERSISTENT ALL EVENING IN SHOWING THIS DEVELOPMENT AND SO FAR HAVE
BEEN VERIFYING WELL. THUS...CONFIDENCE IS NOW RATHER HIGH THROUGH
THE PERIOD.

/OUTLOOK FOR KMSP/
MON-WED...VFR. WINDS S 5-15KT.


&&

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

$$

SHORT TERM...JRB
LONG TERM...
AVIATION...BORGHOFF



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