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000
FXUS65 KGJT 151708
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1108 AM MDT WED MAY 15 2013

.UPDATE...
ISSUED AT 1108 AM MDT WED MAY 15 2013

CONVECTION HAS JUST STARTED FIRING WITH SOME LIGHTNING STRIKES
BEING DETECTED NEAR THE STEAMBOAT SPRINGS AREA. PLENTY OF
INSTABILITY...CAPE...AND LIFT FROM THE APPROACHING DISTURBANCE
WILL KEEP SHOWERS AND STORMS IN THE FORECAST THROUGH THIS
EVENING. MAIN CONCERN WILL BE PEA-SIZED HAIL IN THE STRONGER
STORMS WITH SOME GUSTY SURFACE WINDS ALSO POSSIBLE. GOING FORECAST
CAPTURES THIS WELL SO NO CHANGES AT THIS TIME.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 306 AM MDT WED MAY 15 2013

FEW LIGHT SHOWERS CONTINUE TO HANG ON ACROSS THE NORTHERN ZONES
THIS MORNING. LATEST SHORT RANGE MODELS SUGGEST THIS ACTIVITY WILL
BE ENDING BY SUNRISE...WITH BRIEF LULL IN THE CONVECTIVE ACTIVITY
THROUGH MID MORNING. SUFFICIENT MID LEVEL MOISTURE REMAINS IN
PLACE TODAY. COMPACT UPPER LOW OVER THE GREAT BASIN WILL BE
TRACKING EAST INTO THE FORECAST AREA THIS AFTERNOON AND
EVENING...JUST IN TIME FOR PEAK HEATING AND MAX INSTABILITY
ACROSS OUR AREA. THIS WILL TRIGGER FAIRLY WIDESPREAD SHOWERS AND
THUNDERSTORMS BY MIDDAY WITH ACTIVITY PEAKING THIS
AFTERNOON...ESPECIALLY OVER THE HIGHER TERRAIN. FLOW BECOMING
STRONG ENOUGH THAT WE SHOULD SEE A LITTLE BETTER ORGANIZATION WITH
THE STORMS TODAY...WITH SEVERAL DRIFTING INTO THE VALLEYS. GUSTY
WINDS THE INITIAL THREAT...BUT AS LOW LEVELS SLOWLY
SATURATE...LOCALLY HEAVY RAINFALL WILL ALSO BE IN PLAY BY LATE
AFTERNOON. HAVE MADE SIGNIFICANT ADJUSTMENTS TO THE POPS
FIELDS...INTRODUCING LIKELY POPS TO MOST OF OUR MOUNTAINS WITH
SCATTERED ACTIVITY FOR MANY OF THE VALLEYS. SHOWERS LINGER THROUGH
LATE TONIGHT...BEFORE ENDING AFTER 3 AM AS THE LOW EXITS TO OUR
EAST. TEMPS WILL BE REMAIN A GOOD 5 TO 10 DEGREES ABOVE NORMAL
TODAY...WITH OVERNIGHT LOWS EXPECTED TO BE LOWER THAN LAST NIGHT
BUT STILL ABOVE NORMAL.

ON THURSDAY THE TROUGH DEEPENS ALONG THE WEST COAST AND THE LOCAL
FLOW BACKS TO SW. AFTERNOON TEMPERATURES AGAIN CLIMB WELL ABOVE
NORMAL PRODUCING MARGINAL INSTABILITY. MID-LEVEL MOISTURE WILL
PRODUCE ISOLATED TO SCATTERED MAINLY MOUNTAIN LATE DAY STORMS BUT
THE INVERTED V ENVIRONMENT THREATENS GUSTY OUTFLOW WIND POTENTIAL
INTO THE VALLEYS. THIS RAISES FIRE WEATHER CONCERNS.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 306 AM MDT WED MAY 15 2013

MOST STORMS AND WIND GUSTS SHOULD END BY SUNSET THURSDAY EVENING. UNDER
PARTIAL CLEARING SKIES OVERNIGHT LOWS WILL DROP TO CLOSER TO NORMAL.

FRIDAY-FRIDAY NIGHT THE TROUGH WORKS INTO THE WESTERN GREAT
BASIN. MARGINAL MOISTURE IS ERODED FRIDAY AFTERNOON FOR LITTLE
CHANCE OF CONVECTIVE STORMS. BUT CONTINUED WARM AFTERNOON
TEMPERATURES WILL ALLOW AFTERNOON MIXING TO AT OR ABOVE 500MB AGAIN
RAISING FIRE WEATHER CONCERNS THROUGH THE AFTERNOON. MOISTURE BEGINS
TO WORK INTO THE FORECAST AREA OVERNIGHT AS THE TROUGH PUSHES INTO
UTAH. MODEL TIMING DIFFERENCES EXIST WITH THE EC FASTEST AND THE
GFS/NAM/CANADIAN KEEPING THE TROUGH NEAR THE NV-UT STATE LINE BY
SATURDAY MORNING.

SATURDAY APPEARS TO BE A TWEENER TYPE OF DAY AS WE WAIT FOR THE
WESTERN TROUGH TO DRIVE FURTHER INLAND INTO THE GREAT BASIN.
EXPECT A GENERAL UPTICK IN POPS BY LATE SATURDAY...WITH GRADUAL
INCREASE IN MID LEVEL MOISTURE IN SOUTHWEST FLOW. MEDIUM RANGE
MODELS SOMEWHAT CLOSE IN GENERAL TRENDS OF INCREASING POPS THROUGH
THE WEEKEND AS A LOW TRIES TO CLOSE OFF ACROSS THE NORTHERN
ROCKIES SUNDAY AND MONDAY. AT THIS TIME...WILL CONTINUE TO NUDGE
THE RAIN CHANCES UP A BIT ABOVE MODEL CONSENSUS. TEMPERATURES
THROUGH THE EXTENDED PERIOD WILL BE SHADING BACK TOWARD MORE
SEASONAL VALUES OVER THE WEEKEND AND INTO THE EARLY PORTIONS OF
NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z NOON THURSDAY)
ISSUED AT 1108 AM MDT WED MAY 15 2013

STORMS AND SHOWERS WILL BE COMMON ACROSS THE FORECAST AREA THIS
AFTERNOON AND EVENING. WIDESPREAD CONVECTION WILL KEEP VCTS IN ALL
TAFS WITH TEMPO GROUPS FOR KEGE AND KASE FROM 18Z THROUGH THE
AFTERNOON HOURS. SOME PEA-SIZED HAIL IS POSSIBLE IN THE STRONGER
STORMS AS IS SOME GUSTY SURFACE WINDS. HIGHER ELEVATIONS MAY ALSO
SEE SOME HEAVIER DOWNPOURS WITH THE STRONGER STORMS. VFR IS
EXPECTED FOR MOST OF THE AREA THOUGH MVFR TO OCCNL IFR UNDER
STRONGER STORMS IS POSSIBLE. MOST CONVECTION SHOULD BE JUST ABOUT
OVER BY 03Z LEADING TO CLEARING SKIES AND WIDESPREAD VFR THROUGH
18Z TOMORROW.

&&

.FIRE WEATHER...(TONIGHT THROUGH MONDAY)
ISSUED AT 306 AM MDT WED MAY 15 2013

CONTINUED WARM AND DRY CONDITIONS MAY BECOME CRITICAL ON THURSDAY
AND FRIDAY AS GUSTY SOUTHWEST WINDS ARE ADDED TO THE MIX.

MUCH WILL BE DEPENDENT ON FUEL CONDITIONS...AND LAND AGENCIES ARE
ENCOURAGED TO KEEP THEIR FUELS STATUS UPDATED.

THE FOCUS FOR ISOLATED CRITICAL FIRE WEATHER CONDITIONS WILL BE IN
SOUTHWEST COLORADO THIS AFTERNOON BUT GREEN UP THERE LESSENS FIRE
THREAT.

THURSDAY...SW WINDS DEVELOP AHEAD OF A TROUGH OF LOW PRESSURE ALONG
THE WEST COAST. TEMPERATURES REMAIN WELL ABOVE NORMAL AND HUMIDITY
MAY BE CLOSE TO THE CRITICAL 15% THRESHOLD. AFTERNOON THUNDERSTORMS
WILL PRODUCE MORE WIND THAN RAIN.

FRIDAY THE PACIFIC TROUGH OF LOW PRESSURE WORKS INLAND. WARM AND
EVEN DRIER CONDITIONS ARE EXPECTED IN THE AFTERNOON THAT SHOULD
PRODUCE DRY ADIABATIC MIXING TO AROUND 18000FT MSL WHERE 35KT WIND
SPEEDS WILL BE AVAILABLE TO MIX TO THE SURFACE.  A FIRE WEATHER
WATCH HAS BEEN ISSUED FOR THE ZONE 203 IN COLORADO BELOW 8000 FEET
WITH THE MAIN AREA OF CONCERN WITH GUSTY WINDS POSSIBLE ALONG THE
I-70 CORRIDOR. THIS WATCH MAY BE EXTENDED INTO FRIDAY AFTERNOON.

LESS HOT CONDITIONS ARE EXPECTED OVER THE WEEKEND AND INTO NEXT WEEK
WITH SCATTERED SHOWERS AND STORMS FAVORING THE NORTHERN MOUNTAINS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
     EVENING FOR COZ203.

UT...NONE.

&&

$$

UPDATE...TGR
SHORT TERM...JDC/JOE
LONG TERM...JDC/JOE
AVIATION...TGR
FIRE WEATHER...JOE