529  
FXUS65 KBOU 230231  
AFDBOU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DENVER/BOULDER CO  
831 PM MDT THU AUG 22 2019  
   
UPDATE
 
 
ISSUED AT 831 PM MDT THU AUG 22 2019  
 
FORECAST EVOLVING PRETTY MUCH AS EXPECTED WITH THE STRONGER STORMS  
ON THE EASTERN PLAINS. STILL ONE STRONG STORM IN SOUTHERN LINCOLN  
COUNTY, BUT REST OF THE CONVECTION HAS WEAKENED. THERE WAS SOME  
REDEVELOPMENT ALONG THE FRONT RANGE WITH NUMEROUS BOUNDARY  
SURGES AND COLLISIONS, BUT INSTABILITY HERE IS LIMITED SO MAINLY  
LIGHT RAIN AND A FEW LIGHTNING STRIKES.  
 
FORECAST HAS ONLY BEEN ADJUSTED TO TAKE INTO ACCOUNT LATEST  
TRENDS. THERE MAY BE SOME STRATUS DEVELOPMENT ON THE EASTERN AND  
NORTHERN PLAINS WITH MOIST SOUTHEAST FLOW, AND PERHAPS A LITTLE  
FOG ON THE RIDGES.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 250 PM MDT THU AUG 22 2019  
 
AFTERNOON CONVECTION UNDERWAY ACROSS MOUNTAINS AND ADJACENT  
PLAINS. STRONGEST ACTIVITY NOW ACROSS DOUGLAS AND ELBERT COUNTIES  
WITH STORMS FIRING ON BOUNDARY AND WILL BE MOVING INTO RICHER AND  
MOIST AIRMASS. WITH INITIAL WEAK CONVECTION ALREADY HAS MOVED  
THROUGH DENVER AREA, EXPECT ANY ADDITIONAL ACTIVITY WILL BE WEAK  
AND MAINLY GUSTY WINDS AS LOW LEVEL MOISTURE HAS MIXED OUT AS PW  
VALUES HAVE DROPPED UNDER A HALF OF AN INCH AND DEWPOINTS ARE DOWN  
INTO THE 30S/LOWER 40S. STRONGEST STORMS STILL BEING TARGETED  
OVER THE NORTHEAST PLAINS, ESPECIALLY ALONG THE CYS RIDGE AND  
THEN PROPAGATING EAST AND SOUTHEAST OVER THE COLORADO NORTHEAST  
PLAINS. DEWPOINTS HOLDING IN THE UPPER 50S/60S OVER THE FAR PLAINS  
WITH DECENT SOUTHEAST WINDS ON THE PLAINS. ML CAPE STILL  
PROJECTED UPWARDS OF 2500J/KG. DESPITE THE WEAKER MID LEVEL WINDS  
OF 10-20KT, LOW LEVEL FLOW SHOULD SUFFICE IN A FEW STRONG TO  
SEVERE STORMS OVER THE PLAINS THROUGH EARLY EVENING.  
 
FOR FRIDAY, ONE MORE DAY OF A SEVERE WEATHER THREAT ON THE PLAINS  
BEFORE DRYING COMES IN OVER THE WEEKEND. THERE WILL BE A DECENT  
UPPER TROF WHICH WILL BE MOVING ACROSS THE NORTHERN ROCKIES WITH THE  
TAIL END MOVING ACROSS NORTHERN COLORADO ON FRIDAY WITH WEAK UPWARD  
ASCENT THROUGH THE PERIOD. LIKE TODAY, THE BEST THREAT OF SEVERE  
STORMS WILL BE NORTH AND EAST OF DENVER WHERE THE RICHER LOW LEVEL  
MOISTURE WILL RESIDE. APPEARS LOW LEVEL MOISTURE WILL MIX OUT OVER  
THE FRONT RANGE WITH THE MAIN THREAT OF GUSTY WINDS. SPC HAS AGAIN  
TARGETED THE NORTHEAST PLAINS FOR A MARGINAL THREAT OF STORMS FOR  
DAMAGING WINDS AND HAIL.  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 250 PM MDT THU AUG 22 2019  
 
DRY NORTHWEST FLOW ALOFT LOOKS TO BE THE RULE ACROSS NORTHERN  
COLORADO IN THE EXTENDED PERIOD. A SERIES OF COOL SURFACE SURGES  
WILL KEEP TEMPS CLOSER TO SEASONAL AVERAGE FOR MUCH OF NEXT WEEK  
WITH BOUTS OF HEAT AND COOL. CRITICAL FIRE WEATHER CONDITIONS MAY  
DEVELOP FOR THE SUNDAY, MONDAY AND TUESDAY TIMEFRAME.  
 
ANY SEMBLANCE OF ORGANIZATION TO THE DEFINED SUBTROPICAL RIDGE  
OVER THE SOUTHERN US IS MOSTLY GONE BY FRIDAY EVENING AS AN  
ENORMOUS STABLE RIDGE OF HIGH PRESSURE CONTINUES TO DEVELOP OVER  
THE EASTERN PACIFIC. THIS EVENTUALLY MAKES FOR A MORE PROGRESSIVE  
FLOW PATTERN ACROSS THE NORTHERN US AS THE EASTERN EDGE OF THIS  
RIDGE BEGINS TO INFLUENCE THE WESTERN AND SOUTHWESTERN US FOR THE  
WEEKEND AND INTO NEXT WEEK. THE FIRST FEATURE TO AFFECT THE  
REGION WILL BE A PASSING SHORT WAVE TROUGH RIDING ALONG THE  
US/CANADIAN BORDER. THIS WILL SEND A COOL FRONT SOUTHWARD ONTO  
THE NE CO PLAINS LATE FRIDAY EVENING. SHOWERS AND STORMS WHICH  
INITIATE FRIDAY AFTERNOON SHOULD INTERACT WITH THIS COOL BOUNDARY  
ON THE FAR EASTERN PLAINS FRIDAY EVENING, SO SCATTERED STORMS  
SHOULD KEEP GOING LATE INTO FRIDAY EVENING AND EARLY SATURDAY AS  
THEY MAKE THEIR WAY OUT OF STATE TO THE EAST.  
 
THE EXITING OF THIS TROUGH EARLY SATURDAY WILL USHER IN THE  
BEGINNING OF AN EXTENDED PERIOD OF DRY NORTHWEST FLOW ACROSS THE  
CENTRAL ROCKIES, INCLUDING NE CO. FOR SATURDAY, WILL EXPECT  
COOLER TEMPS AND DRIER CONDITIONS, ESPECIALLY OVER THE MOUNTAINS,  
FOOTHILLS AND I-25 CORRIDOR. MOIST SOUTHEASTERLY SURFACE RETURN  
FLOW, ON THE WEST EDGE OF THE CENTRAL US LOW LEVEL JET, SHOULD  
SUPPLY ENOUGH MOISTURE FOR A FEW STRONG STORMS ON THE FAR EASTERN  
PLAINS SATURDAY AFTERNOON AND EVENING. DESPITE THE DRIER AIR IN  
THE LOW TO MID-LEVELS OVER THE REGION SATURDAY, WILL NOT EXPECT  
ANY CRITICAL FIRE WEATHER CONCERNS AT THIS TIME, MAINLY FOR LACK  
OF WIDESPREAD STRONG WINDS OVER THE HIGHER TERRAIN.  
 
A TIGHTENING OF THE MID-LEVEL HEIGHT GRADIENTS DEVELOPS FOR SUNDAY  
INTO SUN NIGHT AS ANOTHER WEAK TROUGH PASSES ACROSS THE NORTHERN  
ROCKIES AND THE HIGH PLAINS REGION OF MT AND THE DAKOTAS. THIS  
WILL INCREASE THE NORTHWESTERLY WINDS SPEEDS IN THE 700-500 LAYER  
FOR SUNDAY. FORECAST SOUNDINGS INDICATE 20-30 KTS OF NORTHWEST  
FLOW NEAR 700MB, SO WITH LOW RHS OVER THE HIGH COUNTRY, CRITICAL  
FIRE WEATHER CONDITIONS MAY BE PRESENT FOR THE HIGH TERRAIN SUNDAY  
AFTERNOON AND POTENTIALLY OUT ONTO THE PLAINS.  
 
AS THE SHORT WAVE TROUGH MOVES EAST INTO THE MINNESOTA-MANITOBA  
REGION, THIS SENDS DOWN A COLD FRONT INTO NE CO FOR MONDAY. THIS  
IS MOSTLY JUST A COOLER TEMP WINDS SHIFT AS LIMITED MOISTURE AND  
LOW LEVEL STABILITY WILL BE ASSOCIATED WITH IT. THIS SHOULD MAKE  
MONDAY THE COOLEST DAY OF THE WEEK WITH TEMPS ONLY REACHING INTO  
THE 70S, WHICH WOULD BE 10-15 DEGF BELOW SEASONAL AVERAGE. WITH  
MODERATE NORTHWEST FLOW ALOFT PERSISTING OVER THE STATE, CRITICAL  
FIRE WX CONDITIONS WILL LIKELY EXIST, PRIMARILY OVER THE MOUNTAINS  
AND HIGH PARKS. COOLER TEMPS AND HIGHER RHS FOR MUCH OF THE DAY  
SHOULD KEEP THE PLAINS OUT OF WILD FIRE CONDITIONS.  
 
TEMPERATURES WILL REBOUND TUESDAY AS THE COOLER AIR FROM MONDAY  
IS MIXED OUT FROM STRONGER SURFACE NORTHWESTERLY FLOW AS A WEAK  
LEE TROF BRIEFLY DEVELOPS BY AFTERNOON HELPING THIS NW TO SE LOW  
LEVEL GRADIENT. WILL EXPECT ANOTHER DRY DAY TUESDAY, AND WITH  
STRONG WINDS OVER THE HIGHER TERRAIN, WILL NEED TO MONITOR IF  
CRITICAL FIRE WX CONDITIONS SPREAD ONTO THE LOWER ELEVATIONS  
AHEAD OF ANOTHER SURFACE COOL FRONT LATE TUE INTO EARLY WED. AT  
THIS TIME, THIS LOOKS TO BE A RATHER STRONG NORTHERLY PUSH OF  
COOLER AIR. THIS SHARPER SURGE/WIND SHIFT CONTAINS LIMITED  
MOISTURE, BUT SHOULD TAKE TEMPS BACK TO NEAR OR BELOW SEASONAL  
AVERAGE FOR WED INTO THUR.  
 
WHAT HAPPENS NEXT, WEDNESDAY AND BEYOND, WILL BE INFLUENCED BY  
THE NORTHWESTERLY TRACK OF TROPICAL STORM IVO IN THE EPAC. THIS  
IS PROJECTED TO MOVE WELL WEST OF THE CALIFORNIA COAST, BUT MAY  
ALLOW THE SUBTROPICAL HIGH TO RE-ESTABLISH AGAIN OVER MEXICO AND  
THE SOUTHWESTERN US FOR LATE TUE THRU THUR. NORTHWEST FLOW ALOFT  
WILL STILL PREVAIL OVER THE CENTRAL ROCKIES FOR THE WED-THUR  
TIMEFRAME, BUT THE BUILDING RIDGE WILL CREATE WEAKER FLOW ALOFT  
ALLOWING FOR MID AND UPPER LEVEL MOISTURE TO DRAW NORTHWARD INTO  
MID WEEK FOR INCREASED POPS ESPECIALLY OVER HIGHER TERRAIN.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 831 PM MDT THU AUG 22 2019  
 
VARIABLE WINDS ASSOCIATED WITH NUMEROUS HIGH BASED CONVECTIVE  
OUTFLOWS SHOULD BEGIN TO SETTLE DOWN 04Z-06Z, WITH NORMAL WIND  
PATTERNS DEVELOPING THEREAFTER. ANY STRATUS THREAT SHOULD REMAIN  
AWAY FROM THE DENVER AREA AIRPORTS AND CLOSER TO KFNL/KGXY AND  
POINTS EAST/NORTH. ON FRIDAY, THERE WILL BE A CHANCE OF  
THUNDERSTORMS AFTER 20Z, WITH VARIABLE AND GUSTY OUTFLOW WINDS UP  
TO 35 KNOTS THE MAIN THREAT.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 226 PM MDT THU AUG 22 2019  
 
CRITICAL FIRE WEATHER CONDITIONS STILL LOOK POSSIBLE FOR THE  
PERIOD OF SUNDAY THROUGH TUESDAY. THE MAIN AREAS SET FOR ELEVATED  
FIRE CONDITIONS WOULD BE THE MOUNTAINS, HIGH PARKS AND EASTERN  
FOOTHILLS EACH DAY. A COOL FRONT WILL PUSH ONTO THE PLAINS EARLY  
MONDAY WHICH WILL ALLOW FOR COOLER TEMPERATURES AND HIGHER  
RELATIVE HUMIDITY ACROSS THE PLAINS AND LOWER FOOTHILL AREAS. FOR  
TUESDAY, MUCH WARMER TEMPERATURES ARE EXPECTED ACROSS THE LOWER  
ELEVATIONS ALONG WITH THE POTENTIAL FOR NORTHWEST WINDS NEAR 25MPH  
NEAR THE FOOTHILLS AND CHEYENNE RIDGE.  
 

 
   
BOU WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...BARJENBRUCH  
SHORT TERM...ENTREKIN  
LONG TERM...FREDIN  
AVIATION...BARJENBRUCH  
FIRE WEATHER...FREDIN  
 
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