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000
FXUS65 KVEF 201629 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
929 AM PDT MON MAY 20 2013

.SYNOPSIS...GUSTY NORTH WINDS AND SLIGHTLY COOLER TEMPERATURES CAN
BE EXPECTED ACROSS THE REGION TODAY THEN LIGHT WINDS WILL RETURN
THIS EVENING UNDER A WEAK RIDGE OF HIGH PRESSURE. A STORM DROPPING
INTO THE PACIFIC NORTHWEST BY TUESDAY WILL BRING PERSISTENT BREEZY
CONDITIONS TO THE REGION FROM MID WEEK INTO THE HOLIDAY WEEKEND WITH
TEMPERATURES NEAR SEASONAL NORMALS.
&&

.UPDATE...MAIN WEATHER CONCERN THIS MORNING IS REGARDING FIRE
WEATHER ALONG THE COLORADO RIVER VALLEY. UPDATED DISCUSSION BELOW.
OTHERWISE...AN UPPER LEVEL SHORTWAVE MOVED THROUGH THE AREA
OVERNIGHT AND IS ON ITS WAY EAST THIS MORNING. SURFACE PRESSURE
GRADIENTS ARE FORECAST TO WEAKEN THIS AFTERNOON AND WINDS ARE
EXPECTED TO BE ON THE DECREASE AS WELL. TEMPERATURES WILL GENERALLY
BE 3-5 DEGREES COOLER TODAY UNDER CLEAR SKIES. THE GRIDDED FORECAST
COVERS THESE TRENDS WELL SO NO UPDATES NEEDED AT THIS TIME.
-SALMEN-
&&

.FIRE WEATHER...LOCALIZED SUSTAINED WIND SPEEDS ARE RIGHT AROUND
WIND CRITERIA BUT RELATIVE HUMIDITIES WERE STILL ABOVE 15% AS OF 9
AM. THE BIG QUESTION FOR TODAY IS WHETHER WINDS WILL BE ABLE TO
SUSTAIN CRITERIA LEVELS FOR A LONG ENOUGH PERIOD (3 HRS) AFTER RH
LEVELS REACH 15%. CURRENTLY THINKING IS THEY WILL NOT AND PLAN ON
JUST MONITORING FOR NOW.

THE WEATHER PATTERN IS SETTING UP TO BRING AN EXTENDED PERIOD
OF SOUTHWEST WINDS TO THE AREA BEGINNING IN THE WESTERN MOJAVE
DESERT ON TUESDAY AND THEN SPREADING DISTRICT WIDE WEDNESDAY AND
THURSDAY. SOUTHWEST WINDS 15 TO 25 MPH WITH GUSTS BETWEEN 35 AND 45
MPH MAY BE SEEN WEDNESDAY AND THURSDAY. DRY AND WARM CONDITIONS WILL
CONTINUE OVER THE REGION DURING THIS TIME FRAME LEADING TO
POTENTIALLY CRITICAL FIRE WEATHER THRESHOLDS. -SALMEN-
&&

.AVIATION...FOR MCCARRAN...NORTH WINDS ARE EXPECTED 10-18 KTS WITH
GUSTS UP TO 25 KTS AT TIME THROUGH THIS MORNING. NORTH TO NORTHEAST
WINDS 6-12 KTS THIS AFTERNOON. WINDS GENERALLY LIGHT AND VARIABLE
TONIGHT INTO TUESDAY MORNING. SKIES WILL REMAIN MOSTLY CLEAR TODAY
WITH HIGH CLOUDS BECOMING BKN-OVC AROUND 25 KFT TONIGHT THROUGH
TUESDAY.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NORTH TO NORTHEAST WINDS ARE EXPECTED OVER MUCH OF THE
AREA TODAY WITH SPEEDS 10-20 KTS. STRONGEST WINDS WILL BE DOWN THE
COLORADO RIVER VALLEY WHERE WINDS GUSTING UP TO 30 KTS WILL OCCUR
LATE THIS MORNING AND AFTERNOON. FEW-SCT CU OVER EASTERN LINCOLN AND
NORTHEASTERN MOHAVE COUNTY THIS AFTERNOON...OTHERWISE MOSTLY CLEAR.
HIGH CLOUDS INCREASING TONIGHT. -HARRISON-
&&

.PREVIOUS DISCUSSION...320 AM PDT...

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...A TRAILING SHORTWAVE
ON THE BACK SIDE OF THE NORTHERN PLAINS LOW WILL SLIDE DOWN THROUGH
SOUTHEAST NEVADA AND SOUTHWEST UTAH THIS MORNING THEN TRACK ACROSS
THE FOUR CORNERS REGION BY THIS AFTERNOON. THIS WILL PROVIDE A
REINFORCING SHOT TO NORTH WINDS OVER MUCH OF THE FORECAST AREA THIS
MORNING. THE LATEST HIGH RESOLUTION MODELS INDICATE SPEEDS
WILL GENERALLY BE IN THE 15-25 MPH RANGE THIS MORNING. GUSTS OF
30-35 MPH ARE LIKELY FROM LAUGHLIN-BULLHEAD CITY TO NEEDLES THIS
MORNING THROUGH EARLY AFTERNOON. WIND SPEEDS ARE EXPECTED TO
DECREASE THIS AFTERNOON DUE TO A RELAXING SURFACE PRESSURE GRADIENT
ALONG THE EASTERN NEVADA BORDER AND LIGHTER FLOW ALOFT AS A SHORT
WAVE RIDGE QUICKLY MIGRATES OVER NEVADA. THIS RIDGE WILL PUSH EAST
TUESDAY MORNING IN RESPONSE TO A DEEP CLOSED LOW DROPPING INTO THE
PACIFIC NORTHWEST TUESDAY AND PARKING OVER WASHINGTON AND OREGON
THROUGH WEDNESDAY AND BEYOND. SOUTHWEST BREEZES WILL SPREAD ACROSS
THE REGION TUESDAY AFTERNOON AND EVENING THEN SPEEDS ARE FORECAST TO
INCREASE WEDNESDAY AFTERNOON AS THE BASE OF THE SYSTEM DIGS INTO THE
GREAT BASIN. THESE PERSISTENT WINDS AND DRY WARM CONDITIONS WILL
ELEVATE FIRE WEATHER CONCERNS BY WEDNESDAY AFTERNOON.

.LONG TERM...OVERALL THE EXTENDED PATTERN HAS NOT CHANGED MUCH AS A
DEEP UPPER LOW REMAINS SITUATED OVER WA/OR ON THURSDAY. THIS WILL
LEAD TO A CONTINUATION OF GUSTY SOUTHWEST WINDS OVER MUCH OF THE
AREA. THE MODELS SHOW THE LOW TO FINALLY LIFT NORTHEAST FRIDAY...BUT
LEAVING A WEAK TROUGH OVER THE WEST COAST THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK. STILL POSSIBLE TO SEE SOME GUSTY WINDS FROM
TIME TO TIME THROUGH THE WEEKEND...BUT THE STRONGEST WINDS WILL HAVE
ENDED. TEMPERATURES WILL REMAIN CLOSE TO NORMAL THROUGH THE EXTENDED
PERIOD.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&

$$

ADAIR/GORELOW

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