263  
FXUS63 KARX 220736  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
236 AM CDT FRI SEP 22 2017  
   
SHORT TERM
 
(TODAY THROUGH SUNDAY)  
ISSUED AT 236 AM CDT FRI SEP 22 2017  
 
WATER VAPOR SATELLITE THIS MORNING SHOWS RIDGING ALOFT EXTENDED  
FROM NORTHERN MEXICO/TEXAS NORTHEAST INTO QUEBEC. TROUGHING  
EXTENDED FROM THE ROCKIES TOWARD HUDSONS BAY. VERY LITTLE EASTWARD  
MOVEMENT IN THIS PATTERN IS EXPECTED THROUGH THE WEEKEND AS THE  
TROPICAL SYSTEMS OVER THE ATLANTIC HOLD THE RIDGE IN PLACE WHICH  
IN TURN KEEPS THE TROUGHING OVER THE ROCKIES. VERY LITTLE MOVEMENT  
IS EXPECTED IN THE LOW LEVELS AS WELL WITH RIDGING REMAINING OVER  
THE EASTERN CONUS. THE COLD FRONT THAT IS OVER THE DAKOTAS THIS  
MORNING WILL NOT MOVE MUCH THROUGH TONIGHT. FROM SATURDAY INTO  
SUNDAY, THE NORTHERN PORTION OF THE FRONT WILL ATTEMPT TO EDGE  
EAST AS THE AREA OF LOW PRESSURE OVER COLORADO AND NEBRASKA MOVES  
NORTHEAST ALONG THE FRONT AND THEN EAST OVER THE TOP OF THE  
SURFACE RIDGE PULLING THE FRONT WITH IT.  
 
WITH THIS PATTERN, THE STRONG LOW LEVEL SOUTH/SOUTHWEST FLOW WILL  
REMAIN IN PLACE. THIS WILL CONTINUE TO PUMP WARM AIR INTO THE  
REGION WITH 925 MB TEMPERATURES TODAY EXPECTED TO BE AROUND 26 TO  
27C. FORECAST SOUNDINGS INDICATE THE MIXING WILL BE DEEP ENOUGH TO  
TAP INTO THIS WARM AIR AND WITH SOME COMPRESSIONAL WARMING, HIGHS  
TODAY FOR MUCH OF THE AREA WILL BE IN THE LOWER 90S WITH SOME MID  
90S POSSIBLE. FOR SATURDAY, THERE IS THE SUGGESTION THAT  
TEMPERATURES ALOFT WILL COOL SLIGHTLY, MAYBE 1-2C, AND THE MIXING  
WILL STILL BE DEEP ENOUGH TO TAP INTO THIS WARM AIR. CURRENT  
FORECAST HIGHS FOR SATURDAY ARE IN THE UPPER 80S WHICH SEEMS LIKE  
TOO MUCH COOLING COMPARED TO TODAY'S FORECAST WITH VERY SIMILAR  
TEMPERATURES ALOFT. IF THE LOWER TO MID 90S ARE REALIZED TODAY,  
THEN SATURDAY WILL DEFINITELY NEED TO BE WARMER. LITTLE CHANGE  
FOR SUNDAY WITH HIGHS AGAIN IN THE MIDDLE TO UPPER 80S.  
 
LITTLE CHANCE FOR ANY RAIN THROUGH THE WEEKEND WITH THE FRONT  
REMAINING WELL TO THE WEST OF THE AREA. MAYBE SOME ACTIVITY THAT  
DEVELOPS ALONG THE FRONT SUNDAY AFTERNOON OVER MINNESOTA COULD  
POSSIBLY EDGE FAR ENOUGH EAST TO GRAZE THE FAR NORTHWESTERN  
SECTIONS OF THE FORECAST AREA, BUT THIS LOOKS TO BE A VERY LONG  
SHOT AND WILL ONLY HAVE SOME VERY SMALL RAIN CHANCES FOR THIS  
POSSIBILITY.  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 236 AM CDT FRI SEP 22 2017  
 
HOW THE PATTERN WILL EVOLVE NEXT WEEK ALL REVOLVES AROUND WHAT  
HAPPENS WITH THE TROPICAL SYSTEMS OVER THE ATLANTIC. RIGHT NOW,  
JOSE IS STILL MEANDERING OFF THE NORTHEAST COAST. BY EARLY NEXT  
WEEK, THE MODELS ARE ALL SHOWING THAT JOSE WILL HAVE WEAKENED TO  
THE POINT TO NO LONGER ACT AS A BLOCK TO THE RIDGING WHICH IS THEN  
EXPECTED TO MOVE TO THE NORTH AND THEN NORTHEAST SIDE OF MARIA IS  
IT COMES NORTH OFF THE EAST COAST. WITH THIS EASTWARD PROGRESSION  
OF THE RIDGE, THE WESTERN TROUGH IS THEN FINALLY ALLOWED TO WORK  
EAST AND MOVE PAST THE UPPER MIDWEST WEDNESDAY. WITH THIS  
EVOLUTION IN THE UPPER AIR PATTERN, THE SURFACE FRONT IS THEN  
FINALLY ALLOWED TO MOVE EAST AS WELL. CURRENT TIMING WOULD HAVE IT  
APPROACH THE AREA MONDAY, MOVING ACROSS THE AREA TUESDAY AND  
ESSENTIALLY BE TO THE EAST FOR WEDNESDAY AND THURSDAY. THE 22.00Z  
CMC IS SLOWER TO BRING THE TROUGH AND COLD FRONT EAST AND WOULD  
SUGGEST THE NEED FOR SOME RAIN CHANCES THROUGH WEDNESDAY NIGHT.  
WITH OVERALL CONFIDENCE IN ANY ONE MODEL SOLUTION LOW AT THIS  
POINT, WILL KEEP THE RAIN CHANCES GENERALLY IN THE 30 TO 50  
PERCENT RANGE AS THE FRONT COMES THROUGH AND THEN LINGER SOME LOW  
CHANCES TO HONOR THE CMC.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1145 PM CDT THU SEP 21 2017  
 
SCATTERED THUNDERSTORMS HAVE DEVELOPED ACROSS CENTRAL/NORTHERN MN  
IN THE PAST COUPLE HOURS, BUT ARE EXPECTED TO REMAIN NORTH OF TAF  
AIRFIELDS. BIGGER AVIATION CONCERN WILL BE LOW-LEVEL WIND SHEAR  
OVERNIGHT GIVEN 40 TO 45 KTS IN THE 1500 TO 2000 FT AGL LAYER.  
AFTER SUNRISE FRIDAY MORNING, WIND SHEAR WILL DECREASE AS THE  
BOUNDARY LAYER DEEPENS AND SURFACE WINDS BECOME BREEZY FROM THE  
SOUTH. EXPECT FREQUENT GUSTS INTO THE LOW-MID 20 KT RANGE  
THROUGHOUT THE LATE MORNING/AFTERNOON. SOME VFR CLOUD COVER IS  
POSSIBLE OVERNIGHT, BUT A STRONG THERMAL INVERSION WILL DEVELOP ON  
FRIDAY, RESULTING IN MOSTLY SUNNY/CLEAR SKIES THROUGH THE REST OF  
THE PERIOD.  
 

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

 
 

 
 
SHORT TERM...04  
LONG TERM...04  
AVIATION...ROGERS  
 
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