Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KGJT 192052
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
252 PM MDT TUE MAY 19 2015

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 252 PM MDT TUE MAY 19 2015

THE LATEST PACIFIC STORM WAS CENTERED OVER THE SALT LAKE CITY AREA
EARLY THIS AFTERNOON. A WEAK SHORTWAVE ROTATING THROUGH THE BASE
OF THE ZONALLY ELONGATED LOW GOT THUNDERSTORMS OFF TO AN EARLY
START TODAY. SEVERAL STORMS GENERATED DIME-SIZED HAIL...THOUGH
WIND GUSTS WERE SUBSTANTIALLY WEAKER AS THE LOWER LEVELS OF THE
ATMOSPHERE HAVE MOISTENED THEREBY LIMITING DOWNDRAFT SPEED.
MEANWHILE...WEB CAM IMAGES FROM THE MOUNTAIN AREAS INDICATED SOME
SNOW HERE AND THERE BUT MOUNTAIN PASSES HAD ALL IMPROVED
SIGNIFICANTLY AS COMPARED TO THIS MORNING.

EXPECT SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EVENING
THOUGH THE LOSS OF DAYTIME HEATING COMBINED WITH THE EXIT OF THE
SHORTWAVE DESCRIBED PREVIOUSLY WILL CAUSE MOIST CONVECTION TO
DIMINISH SIGNIFICANTLY BY MIDNIGHT. MODELS INDICATED A FEW SHOWERS
MAY LINGER OVER THE HIGHER TERRAIN OF THE NORTH LATE TONIGHT IN AN
AREA OF WEAK OVERRUNNING...THOUGH ADDITIONAL SNOW ACCUMULATIONS
WILL BE LIGHT AND LOCALIZED. PARTIAL CLEARING WILL TRANSLATE INTO
COOLER OVERNIGHT LOWS WITH READINGS RUNNING ABOUT 5 DEGREES BELOW
NORMAL.

A RIDGE WILL BUILD OVER THE AREA ON WED AND PERSIST THROUGH WED
NIGHT. WHILE DRIER AIR WILL WORK IN FROM THE SOUTH...SOME MOISTURE
WILL LINGER MAINLY OVER THE NORTH AND MOUNTAINS. MODEL CROSS
SECTIONS INDICATE THAT AN OROGRAPHICALLY FAVORED WEST FLOW WILL
CONTINUE TO PRODUCE SHOWERS OVER THE NORTHERN MOUNTAINS EARLY IN
THE DAY...ESPECIALLY ALONG THE PARK...GORE AND FLATTOPS RANGES.
MOISTURE WILL DIMINISH LATE IN THE DAY THROUGH THE EVENING.
HOWEVER DAYTIME HEATING WILL HELP BOOST AFTERNOON CONVECTION...
AGAIN MAINLY OVER THE MOUNTAINS. BY LATE EVENING THUNDERSTORMS
SHOULD DIE OFF...WITH ONLY A FEW SHOWERS LINGERING BEYOND
MIDNIGHT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

THE NEXT LOW PRESSURE SYSTEM RELOADS ALONG THE CENTRAL CA COAST
ON THU. THEN SWINGS INLAND LATE THU NIGHT AND ACROSS THE DESERT
SOUTHWEST/SOUTHERN GREAT BASIN ON FRI/FRI NIGHT. THE RESULTING
SOUTH-SOUTHWEST FLOW WILL BRING ENOUGH MOISTURE FOR SOME DIURNALLY
DRIVEN SHOWERS AND THUNDERSTORMS EACH LATE DAY PERIOD. THE
MOUNTAINS WILL BE FAVORED. ALSO A LEADING DISTURBANCE WILL EJECT
FROM THE PARENT LOW...AND BRUSH THE FORECAST AREA THU EVENING.
THIS WILL PROVIDE A BOOST TO CONVECTION THROUGH THE EVENING...WITH
SHOWERS LINGERING OVERNIGHT.

THERE CONTINUES TO BE SOME DIFFERENCES AT TO THE TRACK OF THE
MAIN LOW PRESSURE TROUGH LATE FRI THROUGH SAT...WITH THE GFS
SLOWER AND FARTHER SOUTH. BUT IT APPEARS THAT A WET WEEKEND IS
AGAIN IN STORE FOR THE AREA. FOR SUNDAY AND BEYOND...THE ECMWF
INDICATES THAT ADDITIONAL AND CLOSELY TIMED LOW PRESSURE
DISTURBANCES WILL PASS OVER THE REGION. THE GFS SHOWS A DISTINCT
RIDGE EARLY IN THE WORK WEEK AFTER THE FIRST LOW EXITS TO THE
EAST...BUT WITH SOME DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS
EACH LATE DAY PERIOD. THEREFORE THE FORECAST WILL REMAIN UNSETTLED
THROUGH THE END OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1042 AM MDT TUE MAY 19 2015

UNSTABLE CONDITIONS LATE THIS MORNING AND INTO THE EVENING PERIOD
WILL KEEP SHOWERS AND THUNDERSTORMS IN THE PICTURE FOR EASTERN
UTAH AND WESTERN COLORADO. THREATS TO AVIATION INCLUDE GUSTY WINDS
AND SMALL HAIL AND IMPACTS TO FLIGHT CONDITIONS AND MVFR TO IFR
CONDITIONS FORM UNDER HEAVIER PASSING SHOWERS. WILL USE RADAR TO
FINE TUNE FIRST PART OF FORECAST BUT EXPECT SOME TEMPO GROUPS FOR
UNPREDICTABILITY OF THE CONVECTIVE CONDITIONS. MOUNTAIN
OBSCURATION WILL ALSO CONTINUE UNTIL EARLY WEDNESDAY MORNING WHEN
THIS STORM PULLS FARTHER EAST.


&&

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

$$

SHORT TERM...NL/EH
LONG TERM...EH
AVIATION...TGJT


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.