Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 280519
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1219 AM CDT SUN SEP 28 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 400 PM CDT SAT SEP 27 2014

ALTHOUGH THE MAJORITY OF THE CWA STILL STANDS A DECENT CHANCE OF
MAKING IT THROUGH THE NEXT 24 HOURS DRY...A SLIGHT 20 PERCENT
CHANCE OF SHOWERS/A FEW THUNDERSTORMS HAS BEEN MAINTAINED/EXPANDED
IN THE FORECAST FOR GENERALLY THE NORTHEAST HALF OF THE CWA
(INCLUDING THE TRI-CITIES) FROM LATE TONIGHT INTO SUNDAY MORNING.
PLEASE NOTE THIS PRECIP CHANCE...ALBEIT SMALL...REPRESENTS A
CHANGE FROM THE PRECIP-FREE FORECAST ADVERTISED A FEW DAYS AGO FOR
THIS WEEKEND. OUTSIDE OF THIS PRECIP CHANCE...BOTH TONIGHT AND
SUNDAY ARE EXPECTED TO CLOSELY RESEMBLE LAST NIGHT/TODAY IN MANY
WAYS...INCLUDING TEMPERATURES/WIND SPEEDS. IN OTHER WORDS VERY
STATUS QUO.

STARTING WITH THE HERE AND NOW AS OF 2030Z/330 PM...ANOTHER
SEASONABLY WARM...MOSTLY SUNNY AND BREEZY AFTERNOON IS
ESTABLISHED ACROSS THE AREA...WITH REALLY ABOUT THE ONLY
NOTICEABLE DIFFERENCE BETWEEN FRIDAY AND TODAY BEING A SCATTERED
COVERAGE OF SHALLOW FAIR WEATHER CUMULUS OVER MUCH OF THE
CWA...SIGNIFYING ONLY A SLIGHT INCREASE IN LOW-LEVEL MOISTURE. ON
THE MID-AFTERNOON SURFACE MAP...A DECENT PRESSURE GRADIENT IS
SET UP ACROSS THE CENTRAL PLAINS BETWEEN A BROAD HIGH CENTERED
OVER THE GREAT LAKES REGION AND A LOW PRESSURE TROUGH GENERALLY
ALIGNED FROM SOUTHWEST SD INTO COLORADO. THIS GRADIENT...ALONG
WITH MIXING UP INTO THE 850-800 MILLIBAR LAYER PER FORECAST
SOUNDINGS...IS DRIVING SUSTAINED SOUTH-SOUTHEAST BREEZES GENERALLY
15-22 MPH ACROSS THE CWA WITH GUSTS GENERALLY 22-30 MPH.
HIGH TEMPERATURES APPEAR VERY MUCH ON TRACK TO END UP WITHIN
GENERALLY 1 DEGREE OF THE EARLY-MORNING FORECAST...WITH NEARLY THE
ENTIRE CWA LIKELY TOPPING OUT IN THE 81-85 RANGE. SURFACE
DEWPOINTS HAVE AGAIN MIXED DOWN SOMEWHAT AS OCCURRED THE PAST FEW
DAYS...BUT THIS TIME AROUND SEEM TO BE HOLDING MORE FIRMLY UP INTO
THE 50S THAN YESTERDAY GIVEN THE SLIGHT JUMP IN LOW-LEVEL
MOISTENING. IN THE MID-UPPER LEVELS...WATER VAPOR SATELLITE AND
SHORT TERM MODEL DATA CONTINUE TO DEPICT A HIGHLY AMPLIFIED/BLOCKY
PATTERN. STARTING IN THE WESTERN CONUS...A DEEP/EXPANSIVE TROUGH
IS EVER-SO-SLOWLY PUSHING EAST...WITH ITS CLOSED 500MB LOW
CHURNING OVER THE CA/NV BORDER AREA. JUST EAST OF THIS TROUGH...A
NARROW BUT EVIDENT RIDGE AXIS IS CENTERED FROM THE SOUTHERN
ROCKIES INTO THE DAKOTAS. JUST EAST OF THIS RIDGE AXIS AND ALONG
THE EASTERN PERIPHERY OF THE LOCAL AREA...A SLOWLY-MEANDERING MID
LEVEL LOW CUT OFF FROM THE MAIN FLOW IS CENTERED OVER FAR
NORTHWEST IA AT THIS TIME...WITH ITS CYCLONIC FLOW RESULTING IN
NORTHERLY FLOW FROM NEAR/ABOVE THE 500MB LEVEL OVER THE LOCAL
AREA...WHILE JUST BELOW THIS...PREVAILING SOUTHERLY FLOW IS NOTED
OVER THE LOCAL AREA FROM AROUND 700MB DOWNWARD TO THE SURFACE. ANY
ISOLATED SHOWERS/STORMS ASSOCIATED WITH THIS LOW ARE WELL OFF TO
THE NORTHEAST ALONG THE IA/MN BORDER AREA.

LOOKING AHEAD IN THE FORECAST AND STARTING WITH LATE THIS
AFTERNOON THROUGH THIS EVENING (AT LEAST MIDNIGHT)...DRY
CONDITIONS ARE EXPECTED TO PERSIST CWA-WIDE UNDER MOSTLY CLEAR
SKIES...RESULTING IN A PLEASANT EVENING. AS TYPICAL...BREEZES WILL
EASE DOWN TOWARD SUNSET WITH SUSTAINED BREEZES THROUGH MOST OF THE
NIGHT ONLY AVERAGING 7-13 MPH FROM THE SOUTHEAST.

THEN FOR THE LATE NIGHT HOURS (ESPECIALLY POST-08Z/2AM)...THATS
WHEN A SLIGHT CHANCE OF SHOWERS/ISOLATED STORMS KICKS IN FOR AREAS
MAINLY EAST/NORTHEAST OF AN ORD-KEARNEY-MANKATO LINE. TO BE
SURE...THIS IS STILL A FAIRLY UNCERTAIN SCENARIO...AS THERE IS
VARIANCE BETWEEN BOTH DETERMINISTIC MODEL QPF SUCH AS FROM THE
ECMWF (DRY) AND NAM12 (WHICH SHOWS ISOLATED CONVECTION MAINLY IN
THE FAR NORTHEAST CWA)...AND ALSO FROM HIGHER-RES SOLUTIONS SUCH
AS THE 4KM WRF-NMM AND ARW...THE FORMER OF WHICH IS MORE
SUPPORTIVE OF ISOLATED LATE NIGHT CONVECTION THAN THE LATTER. AT
ANY RATE...ANY STORMS THAT MIGHT MATERIALIZE ARE EXPECTED TO BE ON
THE WEAK SIDE GIVEN ELEVATED MUCAPE GENERALLY ONLY AVERAGING
AROUND 500 J/KG OR LESS. AS FOR FORCING MECHANISMS FOR THIS
POSSIBLE CONVECTION...IT LIKELY HAS LESS TO DO WITH THE NEARBY MID
LEVEL LOW TO THE EAST AND MORE TO DO WITH MODEST THETA-E
ADVECTION/ISENTROPIC LIFT EVIDENT IN THE 850-700MB LAYER AND ON
THE 305/310K ISENTROPIC SURFACES. THE MILLION DOLLAR QUESTION IS
WHETHER OR NOT THIS FORCING WILL BE ENOUGH TO GENERATE ONLY MID
LEVEL CLOUDS...OR ACTUAL SHOWERS/STORMS. OBVIOUSLY WE ARE KEEPING
POPS LOW AT ONLY 20 PERCENT...BUT AT THE SAME TIME CANNOT IGNORE
THE POTENTIAL GIVEN THE AFOREMENTIONED FORCING...AND DESPITE THE
ABSENCE OF A FORMAL GENERAL THUNDERSTORM AREA PORTRAYED ON THE
LATEST SPC DAY 1 OUTLOOK. AS FOR THE AFOREMENTIONED MID LEVEL LOW
OVER NORTHWEST IA...IT WILL REMAIN NEARLY STATIONARY TONIGHT AS IT
STARTS TO OPEN UP AND WEAKEN A TOUCH. AS FOR LOW TEMPS...MADE VERY
LITTLE IF ANY CHANGE FROM PREVIOUS FORECAST...AGAIN EXPECTING VERY
SIMILAR VALUES TO LAST NIGHT WITH MOST OF THE CWA BOTTOMING OUT
57-60.

TURNING TO THE SUNDAY DAYTIME HOURS...AND STARTING WITH THE MID-
UPPER LEVEL BIG PICTURE...THE HEART OF THE NARROW RIDGE AXIS
CURRENTLY JUST WEST OF THE LOCAL AREA WILL SLIDE EASTWARD OVER THE
CENTRAL PLAINS...AS THE LEADING EDGES OF THE EXPANSIVE WESTERN
CONUS TROUGHS STILL REMAINS SAFELY WEST OF THE LOCAL AREA.
MEANWHILE...THE MID LEVEL LOW OVER NORTHWEST IA WILL CONTINUE TO
WEAKEN...OPEN UP AND FINALLY GET ON THE MOVE AS IT STARTS
DEPARTING SOUTHEAST INTO NORTHERN MO. AS FOR PRECIP
CHANCES...ESSENTIALLY CONTINUED THE SLIGHT CHANCE OF
SHOWERS/ISOLATED THUNDERSTORMS FROM THE OVERNIGHT HOURS INTO THE
MORNING HOURS...WHILE GRADUALLY ENDING THESE SLIGHT POPS FROM WEST
TO EAST...WITH THE OVERALL-BEST CHANCES LIKELY FAVORING THE
HIGHWAY 81 CORRIDOR COUNTIES. FOLLOWING ALONG WITH THE 18Z NAM
SOLUTION...CONFIDENCE REMAINED HIGH ENOUGH TO KEEP THE AFTERNOON
HOURS VOID OF ANY PRECIP MENTION AS THE BAND OF MID LEVEL
SATURATION/ISENTROPIC LIFT WEAKENS AND/OR SLIDES OFF EAST OF THE
AREA. AT THE SURFACE...THERE WILL ESSENTIALLY BE LITTLE CHANGE
FROM TODAY...ALTHOUGH THE CENTRAL PLAINS PRESSURE GRADIENT MAY
ACTUALLY BE JUST A TOUCH WEAKER. AS A RESULT...SUSTAINED SOUTH-
SOUTHEAST BREEZES SHOULD AVERAGE JUST A FEW MPH WEAKER THAN THOSE
OF TODAY...WITH SUSTAINED SPEEDS GENERALLY 12-18 MPH MUCH OF THE
DAY AND GUSTS GENERALLY 20-25 MPH. AS FOR HIGH TEMPS...ASSUMING
THAT PLENTY OF SUNSHINE SHOWS ITS HAND ESPECIALLY BY
AFTERNOON...SEE LITTLE REASON WHY HIGHS WON/T BE ALMOST IDENTICAL
TO THOSE OF TODAY. IN FACT...ESSENTIALLY COPIED-PASTED TODAY/S
HIGHS IN FOR SUNDAY...MEANING GENERALLY 81-85 WITHIN THE CWA.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 400 PM CDT SAT SEP 27 2014

CHANGES ARE COMING IN THE EXTENDED PERIODS AS THE UPPER LEVEL LOW
ACROSS THE DESERT SOUTHWEST LIFTS NORTHEAST ON MONDAY...BRINGING THE
CHANCE FOR SOME UNSETTLED WEATHER BEGINNING MONDAY EVENING. WITH THE
ASSOCIATED LONGWAVE TROUGH SLOWLY TRAVERSING THE PLAINS THROUGH THE
END OF THE WEEK...EXPECT MULTIPLE UPPER LEVEL DISTURBANCES IN WEST
TO NORTHWESTERLY FLOW ALOFT TO BRING ADDITIONAL CHANCES FOR SOME
SHOWERS OR THUNDERSTORMS THROUGH AT LEAST EARLY FRIDAY MORNING.

WITH A MILD AIRMASS WILL BE IN PLACE ACROSS THE REGION TO START THE
EXTENDED PERIODS...EXPECT NICE TEMPERATURES TO CONTINUE INTO MONDAY
AFTERNOON AHEAD OF THE AFOREMENTIONED TROUGH OF LOW PRESSURE. THAT
SAID...WITH THE PRESSURE GRADIENT STARTING TO TIGHTEN AHEAD OF A
DEVELOPING SURFACE LOW ON THE LEE SIDE OF THE ROCKIES...EXPECT A
RELATIVELY BREEZY AFTERNOON...ESPECIALLY ACROSS THE WESTERN FRINGES
OF THE FORECAST AREA. THEN AS WE TRANSITION INTO THE EVENING
HOURS...EXPECT CHANCES FOR PRECIPITATION TO INCREASE...AS THE UPPER
LEVEL LOW CROSSES WESTERN NEBRASKA AND BROAD SCALE LIFT INCREASES.
WHILE OVERALL QPF AMOUNTS DO NOT APPEAR TOO ROBUST ACROSS OUR LOCAL
AREA...GENERALLY IN THE QUARTER TO HALF INCH RANGE...COULD SEE
HIGHER AMOUNTS JUST WEST OF OUR FORECAST AREA WHERE A FEW SEVERE
STORMS MAY DEVELOP AS WELL. LATEST SPC PROBS DO INDICATE THIS 5
PERCENT CHANCE FOR SEVERE WEATHER MONDAY EVENING EXTENDING INTO OUR
WESTERN COUNTIES...AND GIVEN UPWARDS OF 1000 JOULES OF CAPE ALONG
WITH MODEST 0-6KM SHEAR VALUES...WENT AHEAD AND MENTIONED THIS
POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK FOR MONDAY EVENING.

WHILE MORE WIDESPREAD PRECIPITATION SHOULD LIFT NORTH WITH THE UPPER
LEVEL LOW ON TUESDAY...SURFACE CONVERGENCE ALONG THE ASSOCIATED
FRONT COULD FIRE UP SOME AFTERNOON AND EVENING THUNDERSTORMS...
ESPECIALLY SOUTHEAST OF THE TRI CITIES ON TUESDAY...IF THE CURRENT
MODEL DATA HOLDS. ONCE AGAIN...GIVEN SHEAR AND CAPE PROFILES...
CANNOT RULE OUT A MARGINALLY SEVERE THUNDERSTORM ACROSS THE
SOUTHEASTERN QUADRANT OF THE LOCAL AREA TUESDAY AFTERNOON THROUGH
EVENING...AND ADDED THIS TO AFTERNOON HWO AS WELL.

AS THE FIRST UPPER LEVEL LOW LIFTS FROM THE NORTHERN PLAINS INTO
CANADA ON WEDNESDAY...EXPECT A SECOND UPPER LEVEL DISTURBANCE IN
NORTHWEST FLOW TO RAPIDLY APPROACH THE LOCAL AREA WEDNESDAY
AFTERNOON...WHICH WILL EVENTUALLY USHER IN A COOLER AIRMASS FOR THE
END OF THE WEEK. AHEAD OF THIS DISTURBANCE...EXPECT MOISTURE TO POOL
MAINLY ACROSS THE SOUTHEASTERN SECTIONS OF THE FORECAST AREA...WHERE
DECENT CAPE VALUES AND MODERATE SHEAR ONCE AGAIN WILL BE PRESENT
ALONG THE STALLED OUT BOUNDARY. AS A RESULT...DID MAINTAIN SEVERE
THUNDERSTORM MENTION FOR WEDNESDAY AFTERNOON AND EVENING ACROSS
THIS AREA AS WELL.

AFTER THE COLD FRONT PUSHES SOUTHEAST ACROSS THE LOCAL AREA BY
THURSDAY MORNING...CHANCES FOR THUNDERSTORMS WILL END AS INSTABILITY
WANES...WITH YET ANOTHER FAST MOVING UPPER LEVEL WAVE AND
REINFORCING SHOT OF COLD AIR EXPECTED TO CONTINUE LIGHT RAIN CHANCES
ACROSS THE REGION THROUGH FRIDAY MORNING. WHILE NOT BITTERLY
COLD...850 MB TEMPS ARE FORECAST TO DROP FROM THE MID TEENS
WEDNESDAY AFTERNOON...TO THE SINGLE DIGITS BY FRIDAY AFTERNOON
BEHIND THE REINFORCING SHOT OF COOLER AIR. THIS SHOULD TAKE
TEMPERATURES DOWN BELOW CLIMO TO END THE WEEK. MODEL CONSENSUS IS
FAIRLY GOOD LATE IN THE EXTENDED...SO EXPECT HIGH TEMPERATURES TO
STRUGGLE TO REACH THE LOWER 60S ON FRIDAY...WHICH IS EXPECTED TO BE
THE COOLEST DAY OF THE EXTENDED PERIODS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1216 AM CDT SUN SEP 28 2014

HAVE WENT WITH DRY CONDITIONS THRU THE TAF PERIOD AS SHORT TERM
MODELS HAVE BACKED OFF ON PCPN CHANCES TOWARD SUNDAY MORNING. WILL
MONITOR TRENDS BUT CONFIDENCE IS LOW IN DEVELOPMENT. SOUTHERLY
WINDS WILL INCREASE AGAIN ON SUNDAY WITH WIND GUSTS NEAR 20KTS
POSSIBLE.  CLOUDS WILL BE LIMITED TO VFR LEVELS.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.

&&

$$

SHORT TERM...PFANNKUCH
LONG TERM...ROSSI
AVIATION...FAY


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