Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 170001
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
701 PM CDT THU OCT 16 2014

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TONIGHT/...
ISSUED AT 328 PM CDT THU OCT 16 2014

SFC LOW CENTERED OVER NW MN WITH THE ASSOCIATED COLD FRONT
STRETCHING THROUGH WRN MN INTO NW IOWA AND SHOULD PASS THROUGH THE
CWA TONIGHT. WINDS WILL SHIFT TO THE NORTHWEST AND PICK UP LATER
TONIGHT AS THE SFC PRES GRADIENT TIGHTENS AND CAA KICKS IN. LOW
LEVEL MOISTURE INCREASES WITH CLOUDS EXPECTED TO SPREAD ACROSS THE
STATE LATE TONIGHT AS WELL. THEREFORE WITH THE WINDS EXPECTED TO
STAY UP AND SOME INCREASE IN CLOUD COVER...TEMPS SHOULD NOT FALL OFF
AS MUCH AS THE PREVIOUS FEW NIGHTS. HAVE LOWS MAINLY IN THE MID 40S
ACROSS THE CWA WITH A FEW UPPER 40S TO AROUND 50 IN THE USUAL WARMER
LOCATIONS.

.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 328 PM CDT THU OCT 16 2014

THE STRONG SHORT WAVE MOVING ACROSS THE NORTHERN PLAINS TODAY AND
TONIGHT WILL BE INGESTED INTO THE CYCLONIC FLOW OF THE LARGE
NORTHEASTERN CONUS UPPER LOW BY FRIDAY. THIS EVOLUTION COMBINED TO
THE WESTERN RIDGE SHIFTING EAST...WILL SHARPEN THE UPPER NORTHWEST
FLOW ACROSS THE STATE AND RESULT A COUPLE MORE SURGES OF COLD
ADVECTION THROUGH SATURDAY. LARGE STRATUS SHIELD OVER NORTH DAKOTA
SHOULD WRAP DOWN INTO MUCH OF CENTRAL AND NORTHEAST OF IOWA BY
FRIDAY. TEMPERATURES WILL BE RELIANT ON THE AMOUNT OF MIXING THAT
OCCURS DURING THE DAY. EXPECT WIND GUSTS OF 30 TO 35 MPH DURING
THE DAY THUS BREEZY AND MAY APPROACH LOW END WIND ADVISORY
CRITERIA IN THE MORE FAVORABLE LOCATIONS. THE SECOND WAVE OF COLD
ADVECTION WILL NOT ARRIVE UNTIL MID AFTERNOON AND SHOULD NOT HAVE
A BIG IMPACT ON HIGH TEMPERATURES. A FINAL WAVE OF COLD ADVECTION
ARRIVES FRIDAY NIGHT AND WILL KEEP HIGH TEMPERATURES ON SATURDAY
IN THE 50S. PRECIPITATION CHANCES FRIDAY THROUGH SATURDAY WILL BE
MINIMAL WITH THE MID LEVELS OF THE ATMOSPHERE REMAINING QUITE DRY.

SFC HIGH PRESSURE WILL MOVE OVER THE STATE LATE SATURDAY INTO
SATURDAY EVENING. THE SYSTEM WILL BE FAIRLY PROGRESSIVE WITH
RETURN FLOW ALREADY DEVELOPING BY LATE EVENING. MID LEVEL THETA-E
ADVECTION WILL INCREASE THROUGH THE DAY ON SUNDAY. HAVE KEPT
PRECIPITATION OUT OF THE FORECAST AT THIS POINT. DESPITE THE
THERMODYNAMIC FORCING...A LACK OF ORGANIZED MOISTURE AND LITTLE
TO NO KINEMATIC SUPPORT WILL LIMIT POTENTIAL. THE UPPER RIDGE WILL
SHIFT EAST AND EXTEND FROM THE GULF COAST THROUGH THE NORTHERN
PLAINS THROUGH MID WEEK. HAVE LEFT TEMPERATURES NEAR GUIDANCE
THROUGH THIS PERIOD. HOWEVER SOUNDING PROFILES REVEAL A LACK OF
MIXING THROUGH AN INVERSION DURING THIS PERIOD. GIVEN THE
POTENTIAL FOR BETTER MIXING AND A DRY PERIOD...THE CURRENT
FORECAST IS LIKELY A BIT LOW. PRECIPITATION CHANCES ON THURSDAY
WILL BE RELIANT ON TIMING OF ARRIVAL OF THE NEXT SYSTEM FROM THE
WEST TO SUPPRESS THE RIDGE. EVOLUTION OF ANOTHER LARGE UPPER LOW
ACROSS THE EAST COAST WILL BE KEY AND SUSPECT THE ECMWF SLOWER
SOLUTION IS LIKELY MORE REASONABLE.

&&

.AVIATION...17/00Z
ISSUED AT 700 PM CDT THU OCT 16 2014

SHORTWAVE LOOKS TO MOVE ACROSS THE STATE THIS EVENING AND BRING
SOME GUSTY WEST TO NORTHWEST WINDS. ANTICIPATING WINDS TO SHIFT
AND INCREASE BY 02Z AT THE LATEST. VERY STRONG MIXING DEVELOPS
DURING THE DAY ON FRIDAY AND INCREASED WIND GUSTS TO AROUND 30
KNOTS FOR ALL TAF SITES. ALSO...EXPECTING MVFR CIGS TO MOVE IN
BEHIND THE SHORTWAVE BY FRIDAY MORNING AND INTRODUCED 3000 FT CIGS
LATE IN THE TAF PERIOD.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...PODRAZIK


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