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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