498  
FXUS63 KARX 260002  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
700 PM CDT SUN JUN 25 2017  
   
SHORT TERM
 
(TONIGHT THRU MONDAY NIGHT)  
ISSUED AT 220 PM CDT SUN JUN 25 2017  
 
MAIN FCST CONCERNS THIS PERIOD ARE SHRA/TSRA CHANCES LINGERING THIS  
EVENING AND AGAIN MON AFTERNOON, CONTINUED COOL TEMPERATURES.  
 
18Z DATA ANALYSIS HAD BROAD NW FLOW ACROSS THE UPPER MIDWEST. WV  
IMAGERY SHOWED DEEP CYCLONIC FLOW ALOFT OVER THE REGION, WITH  
EMBEDDED SHORTWAVES MOVING SE THRU THE FLOW. ONE OF THESE DROPPING  
ACROSS MN, ALONG WITH DIURNAL WARMING/MIXING, PRODUCING SCT SHRA  
ACROSS MUCH OF THE NW HALF OF WI AND NE 1/3 OF MN. A FEW OF THESE AS  
FAR SOUTH AS THE KLSE AREA. ABUNDANT LOWER LEVEL MOISTURE OVER MUCH  
OF THE REGION TODAY. ALONG WITH THE DIURNAL WARMING/MIXING UNDER THE  
COOL TEMPS AND CYCLONIC FLOW ALOFT PLENTY OF CU/STRATO-CU CLOUDS  
OVER THE UPPER MIDWEST THIS AFTERNOON, HELPING HOLD TEMPS DOWN.  
EARLY AFTERNOON TEMPS ACROSS PARTS OF MN/WI AS MUCH AS 15-25F  
BELOW NORMAL, ONLY IN THE 50S TO LOWER 60S.  
 
25.12Z MODEL RUNS INITIALIZED WELL. SOLUTIONS QUITE SIMILAR AS ONE  
SHORTWAVE IN NW FLOW SLIDE BY THIS EVENING, THEN FOR ANOTHER BUNDLE  
OF SHORTWAVE ENERGY TO DROP SE, MAINLY ACROSS WI, ON MON. GOOD  
CONSENSUS FOR HGTS TO THEN RISE MON NIGHT BUT FLOW ALOFT TO REMAIN  
NW. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD THIS CYCLE.  
 
IN THE SHORT TERM, SHORTWAVE ENERGY PASSING LATE THIS AFTERNOON/  
EARLY THIS EVENING TAKES THE BULK OF THE 925-700MB MOISTURE  
EAST/SOUTH WITH IT. ANY LINGERING SHRA/ISOLATED TSRA OVER THE NE  
SIDE OF THE FCST AREA SHOULD EXIT/END BY MID EVENING, WITH A  
DECREASE OF CLOUDS FROM W TO E WITH THE DRYING AND LOSS OF DIURNAL  
HEATING. A WEAK SHORTWAVE DROPPING ND THIS AFTERNOON DROPS INTO  
WESTERN IA TONIGHT, SPREADING SOME 800-700MB MOISTURE/MOISTURE  
TRANSPORT ACROSS SOUTHERN MN/IA DURING THE LATE EVENING/OVERNIGHT  
HOURS. THE MAIN LIFT WITH THIS PROGGED TO STAY SW OF THE FCST AREA,  
AND WILL LEAVE NE IA DRY TONIGHT. BUT IT DOES LOOK TO SPREAD SOME  
CLOUDS OVER THE SW SIDE OF THE FCST AREA OVERNIGHT. LOWER LEVELS ARE  
DRIER WITH THE NEXT SHORTWAVE TO PASS ACROSS WI MONDAY, BUT MODEL  
SOUNDINGS SHOWING DIURNAL HEATING DEVELOPS SOME CAPE MON AFTERNOON  
ALONG/EAST OF THE MS RIVER. THIS WITH LITTLE CIN DUE TO THE COOL  
TEMPS ALOFT. 20-40% SHRA/TSRA CHANCES WITH PASSAGE OF THE SHORTWAVE/  
MID LEVEL TROUGH AXIS ALONG/EAST OF THE MS RIVER MON AFTERNOON QUITE  
REASONABLE FOR NOW.  
 
NAEFS INDICATES 850MB TEMPS 2-2.5 STD DEVIATIONS BELOW NORMAL  
TONIGHT/MON, MODERATING TO 1-1.5 STD DEVIATIONS BELOW NORMAL BY 12Z  
TUE. TEMPS TONIGHT-MON NIGHT TO REMAIN WELL BELOW NORMAL. WITH  
LIGHTER WINDS AND CLEAR-PARTLY CLOUDY SKIES TONIGHT AND AGAIN MON  
NIGHT, BLEND OF GUIDANCE LOWS MOSTLY IN THE 40S BOTH NIGHTS LOOK  
GOOD. WITH THE SFC RIDGE AXIS NEARBY/OVERHEAD MON NIGHT, WILL HAVE  
TO WATCH THE NORMALLY COLDER, LOW LAYING AREAS ALONG/NE OF I-94 FOR  
A FEW LOWS DIPPING INTO THE 30S BY TUE MORNING. MODEL SOUNDINGS  
INDICATING DIURNAL MIXING TO NEAR 850MB MON, WITH THESE TEMPS  
SUPPORTING THE BLEND OF GUIDANCE HIGHS MOSTLY IN THE MID 60S TO  
LOWER 70S ACROSS THE FCST AREA.  
   
LONG TERM
 
(TUESDAY THRU SUNDAY)  
ISSUED AT 220 PM CDT SUN JUN 25 2017  
 
FOR TUESDAY THRU WEDNESDAY NIGHT: MAIN FCST CONCERNS THIS PERIOD ARE  
INCREASING SHRA/TSRA CHANCES/HEAVY RAIN THREAT CENTERED ON WED.  
 
MODEL RUNS OF 25.12Z IN GOOD AGREEMENT FOR RISING HGTS/SHORTWAVE  
RIDGING TO BUILD ACROSS THE REGION TUE/TUE EVENING, AHEAD OF  
STRONGER SHORTWAVE TROUGHING TO MOVE INTO THE NORTHERN PLAINS.  
DETAIL DIFFERENCES INCREASE BUT CONSENSUS BRINGS THIS TROUGH ACROSS  
THE REGION WED/WED NIGHT. FCST CONFIDENCE GOOD TUE, THEN AVERAGE BY  
WED/WED NIGHT.  
 
TUE STILL TRENDING TO BE THE DRY DAY THIS UPCOMING WEEK AS SFC HIGH  
PRESSURE AND THE SHORTWAVE RIDGING ALOFT BUILD INTO THE REGION. A  
WARMER DAY TUE WITH A RETURN OF SOUTHERLY FLOW/LOW LEVEL WARM  
ADVECTION. EVEN WITH PLENTY OF LATE JUNE SUNSHINE EXPECTED, MIXED  
850MB ONLY SUPPORTING HIGHS MOSTLY IN THE MID/UPPER 70S, STILL ABOUT  
5F BELOW THE NORMALS.  
 
MOISTURE RETURN/TRANSPORT AHEAD OF THE PLAINS TROUGH/LOW PROGGED TO  
ARRIVE LATER TUE NIGHT, THEN SPREADS ACROSS THE FCST AREA IN EARNEST  
WED MORNING. PW VALUES OVER THE WEST SIDE OF THE FCST AREA IN THE  
1.5 INCH RANGE BY 12Z WED, WITH THIS SPREADING EAST ACROSS THE AREA  
THRU WED/WED EVENING. INCREASE OF CAPE GENERALLY LAGS THE MOISTURE  
INCREASE, BUT MODEL SOUNDINGS OVER THE WEST SIDE OF THE FCST AREA  
SHOWING LIFTING SATURATED 750-700MB PARCELS BY LATE TUE NIGHT  
RESULTS IN 500-1000 J/KG CAPE AND MINIMAL/NO CIN. SHRA/TSRA EXPECTED  
TO DEVELOP OVER THE WEST END OR JUST WEST OF THE FCST AREA BY LATE  
TUE NIGHT, THEN SPREAD EAST ACROSS THE FCST AREA WED WITH THE  
MOISTURE TRANSPORT/THETA-E CONVERGENCE AND LOWER LEVEL THERMO-  
DYNAMIC FORCING. GIVEN THE RATHER TIGHT CONSENSUS ON THE FORCING,  
SHRA/TSRA CHANCES IN THE 70-80% RANGE WED, DIMINISHING WED NIGHT AS  
THE SFC FRONT THRU MID LEVEL TROUGH AXIS WOULD PASS ARE QUITE  
REASONABLE. WIDESPREAD CONVECTION FIRING/SPREADING ACROSS IN THE  
MORNING TO RESULT IN PLENTY OF CLOUD COVER AND LOOKS TO KEEP ANY  
SEVERE TSRA RISK TO A MINIMUM. HIGHS WED MAY POTENTIALLY STRUGGLE TO  
REACH 70F. BIGGER CONCERN WED MAY BE LOCALLY HEAVY RAINS. SEE  
HYDROLOGY SECTION BELOW FOR MORE INFO.  
 
FOR THURSDAY THRU SUNDAY (DAYS 4 TO 7): MAIN FCST CONCERNS THIS  
PERIOD INCLUDE SHRA/TSRA CHANCES MUCH OF THE PERIOD AND CONTINUED  
BELOW NORMAL TEMPERATURES INTO EARLY JULY.  
 
MEDIUM RANGE MODEL RUNS OF 25.00Z/25.12Z IN REASONABLE AGREEMENT FOR  
WEAK SHORTWAVE RIDGING TO SLIDE ACROSS THE REGION THU, TO BE QUICKLY  
FOLLOWED BY TROUGHING FOR FRI/SAT THEN RISING HGTS/WEAK RIDGING FOR  
SUN. HOWEVER, AS USUAL THERE ARE PLENTY OF SHORTWAVE DETAIL  
DIFFERENCES WITH SHORTWAVE THRU THE FLOW FOR FRI-SUN. FCST  
CONFIDENCE IS AVERAGE FOR DAY 4-7 PRECIP CHANCES AND ON THE GOOD  
SIDE FOR CONTINUED BELOW NORMAL TEMPERATURES.  
 
THE WEAK SHORTWAVE RIDGING AND A SFC RIDGE AXIS SLIDING ACROSS THE  
AREA BEHIND THE WED SYSTEM SHOULD GIVE THE ARE A GENERALLY DRY DAY  
THU. HOWEVER, WITH POTENTIAL SHORTWAVE DETAIL/TIMING DIFFERENCES,  
SOME SMALL SHRA/TSRA CHANCES IN THE AFTERNOON PER THE MODEL  
CONSENSUS OK FOR NOW. WITH APPROACH/PASSAGE OF THE NEXT TROUGH AND  
PIECES OF SHORTWAVE ENERGY, SHRA/TSRA CHANCES IN THE 20-50% RANGE BY  
LATER THU NIGHT INTO FRI EVENING, THEN DIMINISHING THRU SAT LOOKING  
REASONABLE. PRESENT TIMING WOULD BRING ANOTHER WEAK RIDGE/SFC HIGH  
ACROSS THE AREA SAT NIGHT/EARLY SUN, WITH MORE TROUGHING COMING  
ACROSS THE NORTHERN PLAINS BY LATER SUN. GIVEN SHORTWAVE DETAIL  
DIFFERENCES, CANNOT ARGUE AGAINST THE CONSENSUS SHRA/TSRA CHANCES SAT  
NIGHT/SUN. THU LOOKING TO BE THE DRIER, SUNNIER DAY OF THE DAY 4-7  
PERIOD, ALSO LOOKING TO BE THE WARMEST DAY. WEAK LOW LEVEL COLD  
ADVECTION OVER THE AREA THU, FOLLOWED BY THE TROUGHING AND WHAT  
SHOULD BE PLENTY OF CLOUD COVER FRI/SAT, THU=SAT HIGHS MOSTLY IN THE  
70S LOOK GOOD. POTENTIAL FOR SOME WARMING SUNDAY, BUT GIVEN LESSER  
CONFIDENCE IN THE PRECIP CHANCE DETAILS THE CONSENSUS HIGHS  
REASONABLE FOR NOW.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 700 PM CDT SUN JUN 25 2017  
 
CIGS/VSBY/WX: SHORTWAVE TROUGH AND DAYTIME INSTABILITY DRIVING MOST  
OF THE SHRA/TS AND CLOUDS ACROSS THE REGION AT EARLY EVENING, AND  
EXPECT THESE TO CONTINUE TO MOVE EAST/DIMINISH AS THE EVENING WEARS  
ON. MONDAY ANOTHER SHORTWAVE WILL SLIP ACROSS EASTERN WI. SHOULD  
TRIGGER MORE AFTERNOON CLOUDS AND SCATTERED SHOWERS, BUT HIGHER  
CHANCES FOR EASTERN PARTS OF WI, AWAY FROM THE TAF SITES.  
 
WINDS: SHOULD HOLD WEST-NORTHWEST INTO MONDAY NIGHT. A BIT MORE  
SOUTH/SOUTHWEST AT KLSE TONIGHT IF IT DECOUPLES. WILL WATCH AND MAKE  
ADJUSTMENTS IF NECESSARY. NOT AS BREEZY MONDAY AS PRESSURE GRADIENT  
SLACKENS, BUT DEEP MIXING COULD STILL LEAD TO SOME AFTERNOON  
GUSTINESS.  
 

 
   
HYDROLOGY
 
(LATE TUE NIGHT INTO WED EVENING)  
ISSUED AT 220 PM CDT SUN JUN 25 2017  
 
GIVEN PW VALUES PROGGED TO BE 1.5 TO 1.8 INCHES AND WARM CLOUD  
DEPTHS OF 3500 METERS OR HIGHER, TSRA CENTERED ON WED LOOKING TO BE  
EFFICIENT RAIN PRODUCERS. MAIN CONCERN WED MAY WELL BE LOCALLY HEAVY  
RAINS. RAINS OF THE PAST WEEK-10 DAYS HAVE LEFT MUCH OF THE LOCAL  
LANDSCAPE WITH WET SOILS, AND MOST RIVERS AND STREAMS WITH CONTINUED  
HIGHER THAN NORMAL FLOWS. POTENTIAL EXISTS FOR 1 TO LOCALLY 3  
INCHES OF RAIN FROM LATE TUE NIGHT INTO WED EVENING. IF THE  
HEAVIER RAIN WOULD FALL IN A SHORT PERIOD OF TIME OR ON ONE OF THE  
WETTER PARTS OF THE LANDSCAPE, SOME FLOODING OR FLASH FLOODING  
COULD OCCUR.  
 

 
   
ARX WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
MN...NONE.  
IA...NONE.  

 
 

 
 
SHORT TERM...RRS  
LONG TERM....RRS  
AVIATION.....RIECK  
HYDROLOGY....RRS  
 
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