• Oxford, Iowa, United States (52322)
  • WxZone: IAZ064ICAO: KCIDLat: 41.72NLon: 91.79W

Discussions

300 PM CDT SUN AUG 29 2010

.SYNOPSIS...
INCREASING TEMPERATURES AND LOW LEVEL MOISTURE HAVE MADE THEMSELVES
FELT ACROSS THE AREA TODAY...WITH HEAT INDEX VALUES RISING WELL INTO
THE LOW TO MID 90S. DEWPOINTS ARE NOW UP INTO THE LOW 70S...AND A
NICE CUMULUS FIELD HAS FORMED WITH BASES UP AROUND 4KFT. THE  GENERAL
SYNOPTIC PATTERN HAS NOT CHANGED VERY MUCH...WITH THE SURFACE RIDGE
PLANTED OVER THE EAST COAST AND A SURFACE LOW OVER CENTRAL SOUTH
DAKOTA WITH A WARM FRONT EXTENDING UP INTO NORTH WEST MINNESOTA AND
COLD FRONT DOWN INTO COLORADO.  SOME THUNDERSTORMS HAVE FORMED IN
NORTH DAKOTA IN THE VICINITY OF THE WARM FRONT. UPPER LEVEL ANALYSIS
ALSO SHOWS THE STRONG RIDGE OVER THE EAST COAST AND THE STRENGTHENING
TROUGH OVER THE WESTERN STATES.     ..LE..

&&

.SHORT TERM...TONIGHT AND MONDAY...
ANOTHER QUIET NIGHT AHEAD OF US WITH LITTLE CHANGE IN THE PATTERN.
SOUTH WINDS TO STAY UP TONIGHT...SO THAT EVEN WITH ALL THE INCREASED
LOW LEVEL MOISTURE I DO NOT EXPECT A FOG THREAT AT ALL. TEMPERATURES
SHOULD BE SIGNIFICANTLY WARMER TONIGHT THAN LAST NIGHT...WITH NEARLY
ALL SITES STAYING UP AROUND 70. THE GFS APPEARS TO BE OVERDOING THIS
LOW LEVEL MOISTURE AND INSTABILITY... AS IT IS SPITTING OUT SOME QPF
DURING THE AFTERNOON HOURS TODAY.  HAVE DISCARDED IT FOR THE SHORT
TERM FORECAST.  THE NAM IS DOING BETTER. MONDAY THE LOW LEVEL
MOISTURE INCREASES ENOUGH THAT DIURNALLY DRIVEN SCATTERED SHOWERS AND
EVEN ISOLATED THUNDERSTORMS SHOULD DEVELOP DURING THE LATE MORNING
AND AFTERNOON HOURS.  IT APPEARS THAT THE BEST LOW LEVEL MOISTURE
CONVERGENCE WILL BE MORE INTO NORTHERN ILLINOIS THAN IOWA...SO HAVE
PUT THE HIGHER CHANCE POPS THERE AND WENT WITH ONLY SLIGHT CHANCES OR
DRY OVER THE IOWA COUNTIES.  MAX TEMPS SHOULD BE COOLER MONDAY WITH
THE INCREASED CLOUD COVER AND MOISTURE LEVELS...AND HAVE MAX TEMPS
MAINLY IN THE MID 80S...WITH A FEW UPPER 80S WEST.      ..LE..

.LONG TERM...
MONDAY NIGHT THROUGH TUESDAY NIGHT...AFTER A FAIR AND MILD MON NIGHT
CONTINUED LLVL MOISTURE PUMP OFF THE WESTERN GULF BETWEEN SOUTHEAST
CONUS RIDGE AND APPROACHING NORTHERN ROCKIES BROAD L/W TROF WILL BE
UTILIZED TO FEED MORE WIDESPREAD PRECIPITATION THIS PERIOD.
ISOLATED TO WDLY SCTRD PRE-FRONTAL SHOWERS WILL INCREASE ACRS THE
LOCAL FCST AREA ON TUE WITH THE MOST ORGANIZED CONVECTION TAKING OFF
IN THE PRIME FORCING SWATH AND WEST EDGE OF HIGHER INSTABILITY AXIS
FROM SOUTHEAST NEB...TO NEAR MASON CITY IA AND NORTHEASTWARD ACRS
NORTHWEST WI BY LATE TUE AFTERNOON AND INTO THE EVENING. EXPECT
LOCAL CONVECTION AND DEBRIS TO BE SCTRD ENOUGH ON TUE LONG ENOUGH
FOR DECENT MIXING TO AT LEAST H85 MB TO BOOST TEMPS INTO THE MID AND
UPPER 80S CWA-WIDE...WITH A 90 POSSIBLE SOUTH OF I80. SFC DPTS OF
LOWER 70S AND SUCH HEATING WOULD CREATE SBCAPES OF AT LEAST 2500
J/KG BY TUE AFTERNOON AND EARLY EVENING. BEST SHEAR TO FUEL
ORGANIZED SVR STORMS WILL LOOK TO REMAIN WELL TO THE WEST AND
NORTHWEST OF THE LOCAL FCST AREA...BUT SUPPOSE AN OUTSIDE CHANCE OF
SOME HIGH WIND GUSTS LOCALLY WITH ANY STORM LINE THAT IS ABLE TO
GENERATE AND UTILIZE A SFC COOL POOL LATE TUE AFTERNOON. LATEST
SUITE OF 12Z MODEL RUNS STILL SUGGEST INITIAL FRONTAL BOUNDARY TO SAG
ACRS THE CWA TUE NIGHT AND ALIGN UNDER SOUTHWEST MEAN FLOW...ACTING
AS A CONVERGENT FOCUS FOR MCS GENERATION AND PROPAGATION BY
CONTINUED SOUTHERLY THTA-E RICH LLVL FLOW. PW/S INCREASING TO NEAR
2 INCHES SUPPORTS A HEAVY RAIN THREAT INTO WED MORNING.

IN THE EXTENDED/WED THRU NEXT SUN/...
WEDNESDAY AND THURSDAY...TUE NIGHT MCS WILL BLEED INTO WED MORNING
AND LOOK TO DECAY DIURNALLY WITH LINGERING DEBRIS AND OUTFLOW
BOUNDARIES DRAPED SOMEWHERE IN OR IN THE VCNTY OF THE DVN CWA. MAY
BE ENOUGH LULL IN THE ACTIVITY WED AFTERNOON TO ALLOW TEMPS TO WARM
TO THE CURRENTLY PROJECTED HIGHS ON WED...OR POSSIBLE EVEN WARMER.
MEDIUM RANGE ENSEMBLES AND THE NEW 12Z GEM...ECMWF AND GFS ALL
GENERALLY SUGGEST MAIN UPPER TROF AXIS TO SWEEP ACRS IA WED NIGHT
AND PROVIDE DEEP FORCING FOR ANOTHER MCS ROUND. PROBLEM AT THIS
POINT IS WHERE THE PRIME AXIS FOR THE ACTIVITY WILL SET UP DEPENDING
ON LLVL BOUNDARY LAY OUT AND SFC FRONTAL PROGRESSION. THE VARIOUS
MODELS ARE STILL VARY ON HOW FAR SOUTH OR NORTH MANI MCS TRACK MAY
BE AND FOR NOW WILL MAINTAIN HIGH CHC BLANKET CWA-WIDE THROUGH 12Z
THU. ANOTHER ROUND OF HEAVY RAIN WILL BE THE PRIMARY CONCERN WITH
PROGGED PW/S EVEN HIGHER THAN WHAT IS CURRENTLY DEPICTED FOR TUE
NIGHT. TIMING OF ACTIVITY CLEARING OUT ON THU IS ALSO DEBATABLE
DEPENDING AT THIS TIME DEPENDING ON THE MODEL...BUT FOR NOW WILL
PAINT HIGHER POPS IN THE MORNING WITH HIGH CHANCES MIGRATING
EASTWARD OF THE CWA IN THE AFTERNOON WITH EXPECTED FRONTAL PUSH BY
INCOMING SEASONABLY STRONG CANADIAN LLVL RIDGE AXIS. PREFER THE NEW
12Z ECMWF OF A MORE ROBUST SCENARIO OF THE L/W TROF DIGGING ACRS
THE WESTERN GRT LKS THU NIGHT WITH BRISK CAA AND NORTHWEST FLOW
SUPPORTING A CLEAR OUT AND COOL DOWN THU NIGHT. MAY HAVE LOW TEMPS
IN THE 50S AS EARLY AS FRI MORNING IF THIS SCENARIO IS BUILT UPON BY
UPCOMING MODEL RUNS.

FRIDAY AND SATURDAY...COLL RIDGE AXIS AND THE NEW GFS AND ECMWF
ADVERTISING A COOL INFLUX OF H85 TEMPS OUT OF CANADA DOWN TO NEAR
10 DEGREES C OR EVEN COOLER SUGGEST HIGHS ON FRI MAY BE HELD IN THE
MID 70S. COLD CORE SHOWERS WOULD LOOK TO BE MORE WIDESPREAD ACRS
WI CLOSER TO UPPER COOL POOL AND CYCLONIC FLOW...BUT POSSIBLY CLIP
THE NORTHEASTERN CWA FRI AFTERNOON. FRI NIGHT LOWS IN THE 40S. COOL
TREND BLEED INTO THE START OF THE HOLIDAY WEEKEND WITH HIGHS IN THE
70S AGAIN ON SAT.

SUNDAY...WILL HAVE TO START WATCHING FOR ELEVATED WAA WING TYPE
PRECIPITATION EITHER SUNDAY OR MORE LIKELY SUNDAY NIGHT BY RIDGE
RIDING ENERGY ACRS THE CENTRAL AND NORTHERN PLAINS. POPS NOT REALLY
WARRANTED AT THIS POINT TO TRY AND NAIL DOWN A CHC WINDOW.    ..12..

&&

.AVIATION...
VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. SCT DIURNAL CU DECK
AND AFTERNOON GUSTS TO NEAR 20 KTS WILL DISSIPATE AFTER 00Z. LIGHT
SSE WINDS...AROUND 7 KTS...WILL CONTINUE OVERNIGHT AND SHOULD BE
ENOUGH TO PRECLUDE ANY EARLY MORNING MVFR BR/HZ DEVELOPMENT. AFTER
15Z WINDS WILL INCREASE TO NEAR 10 KTS AGAIN.     ..LEGRO..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

LE/LEGRO/12
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