257
FXUS65 KVEF 280018
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
518 PM PDT SUN SEP 27 2026
KEY MESSAGES
* INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS ARRIVE MONDAY
AND TUESDAY ALONG WITH COOLER TEMPERATURES.
* STRONGER STORMS ACROSS THE COLORADO RIVER VALLEY AND NORTHWEST
ARIZONA MAY PRODUCE FLASH FLOODING, SMALL HAIL, AND STRONG WIND
GUSTS.
* MILD WEATHER AND WARMING TEMPERATURES ARE EXPECTED DURING THE
SECOND HALF OF THE WEEK.
DISCUSSION
THROUGH NEXT WEEKEND.
AFTERNOON SATELLITE IMAGERY DEPICTS A DEEPENING WEST COAST TROUGH
DIGGING SOUTHWARD INTO NORTHERN CALIFORNIA. MEANWHILE, REMNANT
MID AND HIGH LEVEL MOISTURE FROM TROPICAL STORM ODALYS CONTINUE TO
STREAM NORTHWARD INTO THE SOUTHWESTERN US, WITH A BROAD CLOUD
SHIELD AND SOME LIGHT SHOWER ACTIVITY DEVELOPING AS FAR NORTH AS
THE LAS VEGAS VALLEY. THESE TWO FEATURES WILL WORK TOGETHER OVER
THE COMING 48 HOURS TO PRODUCE WIDESPREAD UNSETTLED CONDITIONS,
AND POCKETS OF HEAVY RAINFALL MAINLY SOUTH AND EAST OF THE I-15
CORRIDOR THROUGH TUESDAY EVENING. IN THE MEANTIME, LIGHT SHOWERS
AND LOCALIZED GUSTY WINDS WILL REMAIN POSSIBLE THROUGH THE EVENING
ACROSS SOUTHERN NEVADA ASSOCIATED WITH INCREASING MOISTURE ABOVE
A DRY SUB-CLOUD LAYER. WITH DCAPE VALUES OF 1000-1500 ACROSS THE
REGION, SOME GUSTS EXCEEDING 40 MPH WILL BE POSSIBLE, AND THE KLAS
AIRPORT RECENTLY GUSTED TO 45 MPH AS SOME WEAK SHOWERS MOVED
OVERHEAD.
MOISTURE WILL CONTINUE TO STREAM NORTHWARD OVERNIGHT WITH LIGHT
STRATIFORM PRECIPITATION EXPANDING IN COVERAGE ACROSS NORTHWEST
ARIZONA AND THE SOUTHERN REACHES OF THE COLORADO RIVER VALLEY.
THIS PRECIP SHIELD WILL LARGELY BE ASSOCIATED WITH MOISTURE
STREAMING NORTHWARD FROM TROPICAL STORM ODALYS, AND WILL SHIFT
EASTWARD THROUGH THE DAY ON MONDAY. MEANWHILE, AN INCOMING TROUGH
WILL APPROACH FROM NORTHERN CALIFORNIA THROUGH THE AFTERNOON
RESULTING IN AN INCREASINGLY DIFFLUENT FLOW ALOFT ALONG WITH
STEEPENING LAPSE RATES AS THE MID-LEVELS COOL. THIS WILL RESULT
IN EXPANDING INSTABILITY ACROSS THE COLORADO RIVER VALLEY AND
NORTHWEST ARIZONA THROUGH THE AFTERNOON HOURS. TODAYS HIGH
RESOLUTION GUIDANCE CONTINUES TO STRUGGLE ON HOW FAR WEST TO
INITIATE CONVECTION, BUT MOST OF THE CONVECTIVE ALLOWING MODELS
FAVOR AREAS NEAR OR JUST EAST OF LAS VEGAS AS THE INITIAL STORM
DEVELOPMENT FOCUS AREA, WITH ACTIVITY EXPANDING INTO THE RIVER
VALLEY AND NORTHWEST AZ THROUGH THE AFTERNOON AND EVENING HOURS.
GIVEN THE DYNAMIC FORCING INVOLVED WITH THE INCOMING LOW, AND
STRONG SOUTHWESTERLY WIND SHEAR, A FEW SEVERE STORMS WITH HAIL TO
QUARTER SIZE AND GUSTY SURFACE WINDS WILL BE POSSIBLE.
TRAINING STORMS PRODUCING POCKETS OF INTENSE RAINFALL CAN ALSO BE
EXPECTED GIVEN THE DEEP LAYER SOUTHWESTERLY SHEAR PRESENT AHEAD
OF THE INCOMING LOW. GIVEN THIS, THE PRESENCE OF SOME TRANSIENT
TROPICAL MOISTURE, AND AGREEMENT OF CAM GUIDANCE - EXPANDED THE
FLOOD WATCH TO INCLUDE THE COLORADO RIVER VALLEY AND FAR SOUTHERN
CLARK COUNTY. A FEW WEAK SHOWERS AND STORMS MAY ALSO FORM CLOSER
TO THE LOW CENTER ACROSS THE SIERRA AND GREAT BASIN, BUT ARE NOT
EXPECTED TO BE OF SIGNIFICANT IMPACT.
MOISTURE WILL WRAP AROUND THE LOW AS IT MOVES INTO ARIZONA ON
TUESDAY WITH LINGERING SHOWERS EXPECTED ACROSS SOUTHERN NEVADA AND
NORTHWEST ARIZONA. BY WEDNESDAY, THE LOW WILL SHIFT EAST WITH LOW
AMPLITUDE HIGH PRESSURE BUILDING BACK IN AND A WARMING TREND
COMMENCING.
AVIATION...FOR HARRY REID...FOR THE 00Z FORECAST PACKAGE
ISOLATED
SHOWERS CAPABLE OF PRODUCING GUSTS OF 25 TO 30 KNOTS WILL CONTINUE
INTO THE EARLY EVENING BEFORE DIMINISHING. PREVAILING GUSTS OF 15 TO
20 KNOTS WILL SUBSIDE AFTER SUNSET, BUT SOUTHWESTERLY WINDS WILL
REMAIN ELEVATED BETWEEN 8 AND 10KTS OVERNIGHT. CIGS WILL GENERALLY
REMAIN SCT-BKN AOA 15KFT AGL, ALTHOUGH CIGS DOWN TO 10KFT AGL ARE
POSSIBLE WITH SHOWER ACTIVITY. A SIMILAR DAILY WIND PATTERN IS
EXPECTED AGAIN TOMORROW, WITH SPEEDS AND GUSTS SLIGHTLY LOWER THAN
TODAY. VCTS WAS MAINTAINED AFTER 19Z MONDAY TO ACCOUNT FOR
INCREASING CONFIDENCE IN CONVECTIVE DEVELOPMENT THAT MAY CONTINUE
INTO MONDAY NIGHT. ANY STORMS WILL HAVE THE CAPABILITY TO PRODUCE
STRONG WINDS WITH ERRATIC DIRECTIONS, HEAVY RAIN, LIGHTNING, AND
LOWER CEILINGS.
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...FOR THE 00Z FORECAST PACKAGE...TYPICAL DAILY WIND
PATTERNS ARE EXPECTED AT AREA TERMINALS THROUGH THE TAF PERIOD.
GUSTY SOUTHERLY WINDS WILL PERSIST IN MOST AREAS THROUGH SUNSET. THE
WESTERN MOJAVE DESERT, INCLUDING KDAG, WILL BE THE EXCEPTION, WITH
SOUTH TO SOUTHWEST WINDS CONTINUING INTO THE OVERNIGHT PERIOD. LIGHT
SHOWER ACTIVITY IS EXPECTED AROUND THE LAS VEGAS VALLEY AND CRV
TERMINALS INTO THE EVENING, WITH AN AREA OF ADDITIONAL RAINFALL
IMPACTING KEED AND KIFP LATE TONIGHT AND MONDAY MORNING. MORE
WIDESPREAD CONVECTION IS EXPECTED MONDAY AFTERNOON AND EVENING
ACROSS SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHERN AND EASTERN
SAN BERNARDINO COUNTIES. CIGS WILL GENERALLY REMAIN SCT-BKN AOA
15KFT AGL, ALTHOUGH CIGS DOWN TO 10KFT AGL ARE POSSIBLE WITH SHOWER
ACTIVITY.
SPOTTER INFORMATION STATEMENT
SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER OR IMPACTS ACCORDING TO STANDARD OPERATING
PROCEDURES.
DISCUSSION...OUTLER
AVIATION...MOORE/PLANZ
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
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