Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 230526
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1126 PM MDT WED APR 22 2015

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 234 PM MDT WED APR 22 2015

STRETCHED SHORT WAVE...THAT CUTS ACROSS EAST CENTRAL NEVADA (ELY)
TO SOUTHWEST COLORADO (TELLURIDE)...CONTINUES TO LIFT NORTHWARD
THIS AFTERNOON. ISOLATED STORMS HAVE BEEN SHORT LIVED PULSE TYPES...
BUT GUSTY WINDS IN THE 25-30KT RANGE HAVE BEEN RELATIVELY COMMON.
DRIER AIR FOLLOWS THE SHORT WAVE...SO DIURNAL DRIVEN SHOWERS WILL
END ACROSS SW COLORADO QUICKLY THIS EVENING. SCATTERED LIGHT
SHOWERS WILL LINGER A BIT LONGER OVER NW COLORADO...BUT RAP13 SHOW
THESE ENDING BETWEEN MIDNIGHT-3AM THIS MORNING. THESE SHOWERS ARE
WEAK GIVEN POOR UPWARD FORCING...MOST VALLEY "SHOWERS" WILL BE
ESSENTIALLY SPRINKLES.

THE H7 LOW OVER SOCAL THURSDAY MORNING WILL GET ABSORBED INTO A
PASSING TROUGH THURSDAY NIGHT AS IT REACHES NORTHERN ARIZONA. THE SHORT-
LIVED SOUTHWESTERLY FLOW ACCOMPANIED BY THE UPPER LEVEL LOW
PROGRESSION IS FORECAST TO BRING SLIGHTLY DRIER AIR INTO THE
REGION FOR THURSDAY AND THURSDAY NIGHT...WHICH CAN BE SEEN ON WV
SATELLITE TODAY. DESPITE THE DRIER AIR ON THURSDAY...ISOLATED
SHOWERS ARE STILL EXPECTED AT HIGHER TERRAIN AND PARTICULARLY OVER
NORTHEAST UTAH AS A DISTURBANCE PASSES BY THURSDAY MORNING AND
EARLY AFTERNOON.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 234 PM MDT WED APR 22 2015

AVAILABLE MOISTURE REALLY STARTS TO INCREASE ON FRIDAY FROM THE
WEST. BY SATURDAY MORNING SPECIFIC HUMIDITY VALUES NEAR 5
G/KG...OR IN PRECIPITABLE WATER TERMS AROUND 0.55 INCH WHICH IS
WELL ABOVE THE MEAN CLIMATOLOGICAL PWAT VALUE FOR APRIL 25TH. THE
NOW PHASED UPPER LEVEL TROUGH BY FRIDAY MORNING WILL TREK ACROSS
WESTERN COLORADO...BRINGING MAINLY CLOUD COVER BUT A FEW ISO
SHOWERS IN THE MORNING. BY NOON FRIDAY...SHOWERS ARE EXPECTED TO
PICK UP ACROSS NE UTAH AND NW COLORADO AND INITIATE IN THE SAN
JUANS AND GRAND MESA BY THE AFTERNOON AS WELL. PRECIPITATION WILL
NEVER FULLY DISSIPATE FRIDAY EVENING AS THE REGION REMAINS IN AN
ACTIVE TROUGHY PATTERN THROUGH THE WEEKEND. THE REAL EXCITEMENT
WILL BEGIN ON SATURDAY AS A CLOSED LOW OVER THE PAC NW DIVES
TOWARD THE GREAT BASIN CARRYING A COLD FRONT INTO WESTERN UTAH BY
SATURDAY EVENING. THE PLENTY SUFFICIENT MOISTURE AND UPLIFT AHEAD
OF THE FRONT COULD CREATE BANDS OF SHOWERS AMPLIFIED BY DAYTIME
HEATING. PRECIPITATION WILL CONTINUE OVERNIGHT INTO SUNDAY AS THE
FRONT REACHES THE UT/CO BORDER.

SOME DISCREPANCIES WITH THE LONG RANGE MODELS BY SUNDAY AS THEY
PLACE THE CLOSED LOW IN TWO DIFFERENT SPOTS WHICH WILL MAKE A BIG
DIFFERENCE IN THE OUTCOME. THE GFS/CMC BOTH KEEPING THE CLOSED
LOW OVER WESTERN UT NOON ON SUNDAY WHILE THE EC PROGS THE LOW TO
BE OVER THE FOUR CORNERS AT THIS SAME TIME. WITH ANY OF THESE
SOLUTIONS...CONFIDENCE IS HIGHER THAN USUAL FOR THE DAY 5 FORECAST
THAT CONDITIONS ACROSS EASTERN UT AND WESTERN CO WILL BE WET AND
COOLER. THUNDERSTORMS WILL BE MOST WIDESPREAD ON SUNDAY WITH
HIGHER LAPSE RATES DUE TO THE COOLER AIR AND WITH LIFTING
INITIATED BY THE DIVERGENCE ALOFT FROM THE LOW PRESSURE PASSAGE.
THE RAIN/SNOW LINE WILL DROP ON SUNDAY BUT WILL BE MUCH LESS
DRASTIC THAN OUR WEATHER SYSTEM WHICH PASSED LAST WEEK.

STRONG HIGH PRESSURE BUILDS OVER THE WEST ON TUESDAY AND WILL
HELP TEMPERATURES REBOUND BACK TO NEAR AND ABOVE NORMAL BY THE
MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1123 PM MDT WED APR 22 2015

ISOLATED SHOWERS CONTINUE THIS EVENING AND LOOK TO CONTINUE
THROUGH THE NIGHT THOUGH COVERAGE WILL WANE AS THE MORNING GOES
ON. TOMORROW...ANOTHER DAY OF SHOWERS AND STORMS THOUGH COVERAGE
IS EXPECTED TO BE LESS THAN SEEN TODAY. CONVECTION WILL START
AROUND 18Z WITH THE MAIN CONCERN...AGAIN...BEING GUSTY OUTFLOW
WINDS. MOST PRECIP WILL END AFTER SUNSET BUT A FEW SHOWERS MAY
CONTINUE...MUCH LIKE THIS EVENING.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

SHORT TERM...PF/JAM
LONG TERM...JAM
AVIATION...TGR



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