Area Forecast Discussion
Issued by NWS Grand Junction, CO

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722
FXUS65 KGJT 210318
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
918 PM MDT WED MAY 20 2015

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 104 PM MDT WED MAY 20 2015

THE DAY/S CONVECTION...FUELED MAINLY BY LINGERING LOW LEVEL
MOISTURE AND DIFFERENTIAL/DIURNAL HEATING WILL DIMINISH AS THE
SUN SETS THIS EVENING. A RIDGE OF HIGH PRESSURE WILL REMAIN
OVERHEAD...SLOWING SHIFTING EAST TOWARDS MORNING. THEREFORE THE
ONLY FORCING MECHANISMS FOR LATER EVENING AND OVERNIGHT SHOWERS
WILL BE INTERACTIONS BETWEEN LEFT OVER OUTFLOW BOUNDARIES...AND
THESE SHOULD BE LESS THAN PLENTIFUL. TEMPERATURES WILL GENERALLY
BE NEAR NORMAL FOR MID-LATE MAY.

EXPECT A QUIET START THURSDAY AS THE NEXT PACIFIC LOW TO IMPACT
THE AREA CIRCULATES OFF THE CALIFORNIA COAST AT 12Z. AHEAD OF
THIS SYSTEM FLOW WILL CONTINUE FROM THE SOUTH TO SOUTHWEST
ADVECTING MODERATE MID-LEVEL MOISTURE AND WARMER AIR TO THE
FORECAST AREA. LATER IN THE DAY A SHORTWAVE TROUGH EJECTED FROM
THE EASTERN PACIFIC LOW WILL PUSH OVER THE DESERT SOUTHWEST...
DRIVEN BY A 95 KT MOVING THROUGH THE BASE OF THE SYSTEM. THE
CYCLONICALLY CURVED JET WILL PROVIDE DECENT DIVERGENCE ALOFT
ENHANCING LIFT IN AN AIRMASS DESTABILIZED BY DIURNAL WARMING. THIS
SHOULD YIELD SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS OVER
THE HIGHER TERRAIN BEGINNING LATE IN THE MORNING.

SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THURSDAY NIGHT
SUSTAINED BY FORCING PROVIDED BY THE JET DESCRIBED PREVIOUSLY. THE
FORCING GRADUALLY LIFTS NORTH LATER IN THE NIGHT SO DO ANTICIPATE
A CESSATION OF MOIST CONVECTION ACROSS THE SOUTH AFTER MIDNIGHT.

HIGH AND LOW TEMPERATURES WILL FINALLY RETURN TO NEAR NORMAL
LEVELS THURSDAY AND THURSDAY NIGHT DUE TO THE ADVECTION OF WARMER
AIR MENTIONED PREVIOUSLY.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 104 PM MDT WED MAY 20 2015

THE LOW DISCUSSED IN THE SHORT TERM DISCUSSION WILL TRACK ACROSS
LAS VEGAS ON FRIDAY TO NORTHWEST COLORADO ON SATURDAY. THERE IT
AND BECOMES LESS DISTINCT...SLOWED BY A SECONDARY LOW WHICH WILL
SWEEP SOUTH OF THE AREA SUNDAY. THE NEXT PACIFIC SYSTEM ARRIVES
TUESDAY WITH ANOTHER...FASTER MOVING SYSTEM ARRIVING WEDNESDAY.
ESSENTIALLY...IT LOOKS LIKE THE AREA WILL SEE A CONTINUATION OF
THE UNSETTLED...MOIST...AND SEASONALLY COOL CONDITIONS EXPERIENCED
OVER THE PAST COUPLE OF WEEKS. SHOWERS AND THUNDERSTORMS WILL
BE MOST NUMEROUS DURING THE AFTERNOON/EVENING PERIODS FAVORING THE
HIGHER TERRAIN. NOCTURNAL SHOWERS AND EMBEDDED THUNDERSTORMS WILL
BE PREVALENT DURING PERIODS OF TROUGH PASSAGE. MODELS NOT IN VERY
GOOD AGREEMENT EARLY NEXT WEEK SO MADE FEW ADJUSTMENTS TO POP
FIELDS WHICH MAY BE TOO LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 905 PM MDT WED MAY 20 2015

VFR CONDITIONS WILL BE IN PLACE THROUGH 18Z THURSDAY. AFTER
18Z...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP...
INITIALLY OVER THE HIGHER TERRAIN...BUT SPREADING INTO THE
VALLEYS AFTER 21Z. LOCALLY HEAVY PRECIPITATION...GUSTY WINDS TO
40 KTS AND SMALL HAIL WILL ACCOMPANY THE STRONGEST STORMS ALONG
WITH AREAS OF MVFR TO IFR CIGS AND VSBYS AS THE SHOWERS INCREASE
IN COVERAGE. KTEX AND KASE WILL SEE A 60 PERCENT CHANCE OF THE
SHOWERS MOVING THROUGH WITH THE LOWER VALLEY SITES RUNNING AROUND
30 PERCENT THROUGH THURSDAY EVENING.

&&

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

&&

$$

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



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